I made some calculations in my last post regarding my family's use of fossil fuels. I attempted to determine as complete a picture as I could, including such things as goods consumption, food, etc. I also utilized a very simplistic model, assuming all our fossil fuel consumption could be modeled by the chemical combination of n-heptane with atmospheric oxygen to produce carbon dioxide and water to estimate our production of carbon dioxide as a result of our energy use. While this undoubtedly leads to inaccuracies, I think it is "in the ballpark."
Since publishing that post, I've played a little bit with the so-called "carbon footprint calculators" to be found all over the web. I've also been as thorough with them as I know how and as they will allow. The results are rather disturbing, if one buys into the theory of anthropogenic global warming by way of carbon dioxide emissions. My "ground up" calculations indicated that my family produces 96 tons per year of carbon dioxide emissions, whereas the calculator linked above shows about 44 tons. This is a rather significant under estimation by more than half, if my calculations are correct. And though they may be off, I don't believe that they are off by that amount.
Now I suppose that those who model climate do so using a better estimate of carbon dioxide emissions than a summation of everyone's output from the carbon footprint calculator. Nevertheless, I imagine many people log on to such sites to determine their footprint and what they can do about it. Based on my results, they severely underestimate the extent of the emissions for which they are responsible and the remedial measures they would need to take.
Assuming that the averages shown on the calculator site are off by the same extent as the results of my calculations, my family of four emits carbon dioxide at a rate of about double the national average, a little under four times the average for so-called "industrial countries," about ten times the world average, and about twenty times the worldwide goal. That is, my family would have to reduce its emissions by about 95% to bring us into accord with that goal.
Wow. If both my wife and I stopped driving, and I stopped flying my airplane, we'd reduce our footprint by just over 50%. In fact, our food consumption alone represents over 8% of our carbon footprint, and thus we would have to eliminate all carbon emissions not involving eating and change our eating to less carbon intensive sources to reduce our footprint by 95%. And as I pointed out in the previous post, this does not take into account our pro-rata share of institutional use of fossil fuels such as military, etc.
If this is truly an accurate representation of our situation and only differs from others in the United States by degree but not basic nature, we aren't going to be able to meet such goals no matter how many conferences in Bali are flown to by worldwide climate diplomats. So what then?
After calculating our footprint, we're given the option of "offsetting" all or part of our carbon dioxide emissions. What would I have to do? I'm given three options: contributing $598 to a "Clean Energy Fund;" contributing $777 to Reforestation in Kenya; and contributing $1,304 to "UK Tree Planting." I get a certificate and everything. Keep in mind, however, that these amounts reflect the carbon dioxide calculated by the calculator at the site, not the ones I calculated from scratch. Those would require over double the expenditure. I guess this is how Al Gore flies around the world and lives in a mansion and yet has a positive effect on climate change. Somehow, I don't feel that everyone buying these offsets will solve our problems.
Sunday, December 16, 2007
Saturday, December 08, 2007
Total energy use in my family
In an earlier post I utilized data in the World Almanac and Book of Facts to determine that the total per capita rate of energy consumption in the United States is a little over 11,000 watts. I decided to see where my family and I fall into this. I approximated all of the electrical consumers in the house, the fuel consumption of my vehicle, my wife's vehicle, my airplane, the power I use at work, the power she uses at work, the energy content of the food each of us eats, and the energy content of the items each of us "consumes."
Obviously, many approximations and estimations were necessary but the results are quite interesting to me. It appears that my family of four consumes energy at the rate of about 40,094 watts. This is all-inclusive as best I can make it, but does not include our pro-rata share of government expenditures (this could be significant, considering it would include our share of military expenditures of energy, etc.). Surprisingly, this amounts to 10,023 watts per capita in my family. I find this agreement with the figures from the Almanac to be downright startling and, frankly, quite gratifying. It's a little misleading though, since the Almanac figures are the total of U.S. energy use whereas, as we'll see later, a significant portion of my family's energy consumption likely takes place offshore.
The largest single item is my wife's use of automobile gasoline in her Grand Cherokee Laredo. This came to 11,880 watts. She uses a LOT of gas.The next is her consumption of "stuff." I don't know exactly what she buys, so I used the the money she spends as a proxy. I excluded food, since it's included separately, then figured one third the cost represents energy input. In earlier days it would have been less, since there would be more input of labor but in this automated day and age, I figure one third. Then I estimated the cost of a joule of energy (about $2.778*10^-8) and worked back to rate of consumption normalized to represent continuous consumption. Since the two children that share our house are hers, I lumped all consumption that is not mine into hers. The total for this category is 10,400 watts. This is the where the "offshore" portion mentioned above comes in, since a significant portion of the energy input for our "stuff" purchases is in places like China.
Next came my use of automobile gasoline at 5,049 watts, followed by aviation gas for my airplane at 3,961 watts. The house consumes energy at the rate of about 2,812 watts. I used a separate spreadsheet to go item by item in the house, the largest consumer on the continuous, annualized basis is the refrigerator, followed by the swimming pool pump. My goods consumption comes in at 2,400 watts. Total food for the four of us is 3,294 watts. Amazingly, taking my house completely "off the grid" would only reduce our family's total fossil fuel energy expenditure by about 7%. As an aside, I should point out that I'm carrying many more digits of accuracy than my approximations justify, the best of them are probably good for two significant figures.
From a carbon footprint point of view, I assume that 100% of our energy use comes from burning fossil fuels, and that 6 pounds of fossil fuel provides 125,000,000 joules of energy and produces 19 pounds of carbon dioxide. That means that our rate of energy consumption results in the annual addition to the atmosphere of 96 tons of carbon dioxide. From an economic point of view, my family spends something like $35,000 per year on energy.
I mentioned in my article about the Almanac that I was confident I could reduce my rate of energy consumption by half. I'm less confident now that it would be relatively easy, but circumstances will surely force us to do this and much more. At least I now know where to start looking for the savings.
Obviously, many approximations and estimations were necessary but the results are quite interesting to me. It appears that my family of four consumes energy at the rate of about 40,094 watts. This is all-inclusive as best I can make it, but does not include our pro-rata share of government expenditures (this could be significant, considering it would include our share of military expenditures of energy, etc.). Surprisingly, this amounts to 10,023 watts per capita in my family. I find this agreement with the figures from the Almanac to be downright startling and, frankly, quite gratifying. It's a little misleading though, since the Almanac figures are the total of U.S. energy use whereas, as we'll see later, a significant portion of my family's energy consumption likely takes place offshore.
The largest single item is my wife's use of automobile gasoline in her Grand Cherokee Laredo. This came to 11,880 watts. She uses a LOT of gas.The next is her consumption of "stuff." I don't know exactly what she buys, so I used the the money she spends as a proxy. I excluded food, since it's included separately, then figured one third the cost represents energy input. In earlier days it would have been less, since there would be more input of labor but in this automated day and age, I figure one third. Then I estimated the cost of a joule of energy (about $2.778*10^-8) and worked back to rate of consumption normalized to represent continuous consumption. Since the two children that share our house are hers, I lumped all consumption that is not mine into hers. The total for this category is 10,400 watts. This is the where the "offshore" portion mentioned above comes in, since a significant portion of the energy input for our "stuff" purchases is in places like China.
Next came my use of automobile gasoline at 5,049 watts, followed by aviation gas for my airplane at 3,961 watts. The house consumes energy at the rate of about 2,812 watts. I used a separate spreadsheet to go item by item in the house, the largest consumer on the continuous, annualized basis is the refrigerator, followed by the swimming pool pump. My goods consumption comes in at 2,400 watts. Total food for the four of us is 3,294 watts. Amazingly, taking my house completely "off the grid" would only reduce our family's total fossil fuel energy expenditure by about 7%. As an aside, I should point out that I'm carrying many more digits of accuracy than my approximations justify, the best of them are probably good for two significant figures.
From a carbon footprint point of view, I assume that 100% of our energy use comes from burning fossil fuels, and that 6 pounds of fossil fuel provides 125,000,000 joules of energy and produces 19 pounds of carbon dioxide. That means that our rate of energy consumption results in the annual addition to the atmosphere of 96 tons of carbon dioxide. From an economic point of view, my family spends something like $35,000 per year on energy.
I mentioned in my article about the Almanac that I was confident I could reduce my rate of energy consumption by half. I'm less confident now that it would be relatively easy, but circumstances will surely force us to do this and much more. At least I now know where to start looking for the savings.
Sunday, November 25, 2007
A year's worth of data
For those of you who would prefer to see actual data rather than read my descriptions of what it indicates, I'm publishing a Google spreadsheet that shows the complete data set for my Land Rover LR3 HSE. The Excel spreadsheet is, of course, more extensive and informative, particularly with respect to the charts. But this should certainly be enough to let those who would like to know more about the actual numbers I've achieved satisfy that desire. I apologize for my current inability to format the spreadsheet to the width of the blog, I'll work on it.
Average speed
My Land Rover LR3 HSE has a fairly extensive menu of data on display. One of these displays is "Average Speed." Like all the numbers on the display, it resets when the mileage on the trip odometer (actually one of the two trip odometers) is reset to zero. I do this at each fill up, so the average speed on the indicator shows the average for the current tank full.
The average speed should reflect, among other things, the amount of time I spend on the highway at 55 m.p.h. versus the time I spend on streets and in traffic jams. It crossed my mind eight fill ups ago to add the average speed data for the tank full to the myriad of other data I collect when I fill up. Since highway mileage should be higher, it's reasonable to expect that higher average speeds for a tank should correlate with higher miles per gallon for that tank.
To check this theory, I've plotted m.p.g. on the vertical axis versus average speed on the horizontal axis. As expected, higher speeds are accompanied by higher mileage numbers. The linear trendline, calculated by Excel, has a slope of about 0.32, meaning that each mile per hour increase in average speed over a tank full yields an increase in 0.32 m.p.g. for that tank full. The coefficient of determination ("R squared"), however, is low at 0.48. Thus, while there is a positive correlation between average speed and gas mileage, average speed is a weak predictor of gas mileage. More data will enable a deeper analysis.
For those who are curious about what the actual numbers are, the lowest average speed has been 31.7 m.p.h. and the highest has been 39.1. The latter number was for a tank full the bulk of which was expended on the interstate from Las Vegas to Los Angeles. That tank full produced a fuel economy of 23.41 m.p.g. The lowest average speed produced a fuel economy of 19.82 m.p.g.
The average speed should reflect, among other things, the amount of time I spend on the highway at 55 m.p.h. versus the time I spend on streets and in traffic jams. It crossed my mind eight fill ups ago to add the average speed data for the tank full to the myriad of other data I collect when I fill up. Since highway mileage should be higher, it's reasonable to expect that higher average speeds for a tank should correlate with higher miles per gallon for that tank.
To check this theory, I've plotted m.p.g. on the vertical axis versus average speed on the horizontal axis. As expected, higher speeds are accompanied by higher mileage numbers. The linear trendline, calculated by Excel, has a slope of about 0.32, meaning that each mile per hour increase in average speed over a tank full yields an increase in 0.32 m.p.g. for that tank full. The coefficient of determination ("R squared"), however, is low at 0.48. Thus, while there is a positive correlation between average speed and gas mileage, average speed is a weak predictor of gas mileage. More data will enable a deeper analysis.
For those who are curious about what the actual numbers are, the lowest average speed has been 31.7 m.p.h. and the highest has been 39.1. The latter number was for a tank full the bulk of which was expended on the interstate from Las Vegas to Los Angeles. That tank full produced a fuel economy of 23.41 m.p.g. The lowest average speed produced a fuel economy of 19.82 m.p.g.
Saturday, November 24, 2007
Hills
The only way to my house is to select one of two hills to climb. As I make my choice and climb, I watch the average mileage for that tank full (the LR3 clears the average mileage at fill up when the trip odometer is reset) decrease. And quite a few web sites that discuss gas mileage state that, when possible, use the least hilly route available. This got me to wondering what the effects of hills actually are so, as usual, I decided to do some calculating.
To start, I found the elevation at the bottom and top of the hill I usually climb by getting the latitude and longitude from Google Earth and then plugging the coordinates into the height/elevation tool of EarthTool: Webservices. I determined that I climb 123 meters. Doing this in a vehicle whose mass is, on average, 2,673 kilograms means that I add 3,222,000 joules of potential energy to the vehicle in climbing the hill. This energy comes from burning gasoline, but since I'm only able to use about 25% of the heat of the combustion of fuel, I need four times this amount, or about 12,890,000 joules of heat energy from gasoline. This is the amount in about 0.1 gallons. This is in addition to the fuel I burn just to drive the 2108 meters of road (as measured by Google Earth) to climb the hill.
Since I typically drive this hill at about the speed limit of 35 m.p.h., on level ground I'd get something like 21 m.p.g. and use about 0.062 gallons. Thus, I use much more fuel to climb the hill than I do to drive the distance. Adding the two numbers, I use 0.062 + 0.1 gallons to drive 1.31 miles for a gas mileage number of about 8.1 m.p.g. This squares nicely with what the readout on the panel display says.
BUT... When I go down the hill, I turn my engine off and coast to the bottom of the hill. The distance down is the same as the distance up, so if I drove it on level ground, I'd use the same 0.062 gallons. Instead, I use none. So driving up the hill and coasting down uses 0.162 gallons, driving the same distance on level ground would use about 0.124 gallons. Thus, the necessity of climbing the hill requires the expenditure of 0.038 gallons of fuel. Since I typically do this about five times per fill up, I put something like 0.19 extra gallons of fuel in the tank because I live at the top of a hill.
So how does this affect my fuel economy? Well, let's say I fill up at 340 miles and put in 17 gallons. This is fairly representative, and equates to exactly 20 m.p.g. The extra 0.17 gallons would reduce my mileage to about 19.8 m.p.g. I'm kind of surprised by this result, as I intuitively expect that I'll convert the potential energy going down the hill. If I didn't have to brake going down the hill and if I could hit the bottom, turn the corner and coast down to cruising speed I'd be able to recover a lot more of it, but these actions aren't possible. This means that I end up using the stored potential energy gained by burning fossil fuel to heat the metal in my brakes.
The hill seems pretty steep. Running the trigonometry, it turns out to average 3.34 degrees. It turns out that going up the hill and down adds eight meters to the distance I would travel if there were no elevation change from the location of the beginning of the hill to my house. While I will always turn off my engine and coast the last eight meters into a parking space where possible, it isn't saving much. The extra eight meters driven five times for a fill up use about a thousandth of a gallon. Anyway, traveling up and down hills clearly does not help fuel economy. I guess I should move downhill. Better yet, move next door to my job.
To start, I found the elevation at the bottom and top of the hill I usually climb by getting the latitude and longitude from Google Earth and then plugging the coordinates into the height/elevation tool of EarthTool: Webservices. I determined that I climb 123 meters. Doing this in a vehicle whose mass is, on average, 2,673 kilograms means that I add 3,222,000 joules of potential energy to the vehicle in climbing the hill. This energy comes from burning gasoline, but since I'm only able to use about 25% of the heat of the combustion of fuel, I need four times this amount, or about 12,890,000 joules of heat energy from gasoline. This is the amount in about 0.1 gallons. This is in addition to the fuel I burn just to drive the 2108 meters of road (as measured by Google Earth) to climb the hill.
Since I typically drive this hill at about the speed limit of 35 m.p.h., on level ground I'd get something like 21 m.p.g. and use about 0.062 gallons. Thus, I use much more fuel to climb the hill than I do to drive the distance. Adding the two numbers, I use 0.062 + 0.1 gallons to drive 1.31 miles for a gas mileage number of about 8.1 m.p.g. This squares nicely with what the readout on the panel display says.
BUT... When I go down the hill, I turn my engine off and coast to the bottom of the hill. The distance down is the same as the distance up, so if I drove it on level ground, I'd use the same 0.062 gallons. Instead, I use none. So driving up the hill and coasting down uses 0.162 gallons, driving the same distance on level ground would use about 0.124 gallons. Thus, the necessity of climbing the hill requires the expenditure of 0.038 gallons of fuel. Since I typically do this about five times per fill up, I put something like 0.19 extra gallons of fuel in the tank because I live at the top of a hill.
So how does this affect my fuel economy? Well, let's say I fill up at 340 miles and put in 17 gallons. This is fairly representative, and equates to exactly 20 m.p.g. The extra 0.17 gallons would reduce my mileage to about 19.8 m.p.g. I'm kind of surprised by this result, as I intuitively expect that I'll convert the potential energy going down the hill. If I didn't have to brake going down the hill and if I could hit the bottom, turn the corner and coast down to cruising speed I'd be able to recover a lot more of it, but these actions aren't possible. This means that I end up using the stored potential energy gained by burning fossil fuel to heat the metal in my brakes.
The hill seems pretty steep. Running the trigonometry, it turns out to average 3.34 degrees. It turns out that going up the hill and down adds eight meters to the distance I would travel if there were no elevation change from the location of the beginning of the hill to my house. While I will always turn off my engine and coast the last eight meters into a parking space where possible, it isn't saving much. The extra eight meters driven five times for a fill up use about a thousandth of a gallon. Anyway, traveling up and down hills clearly does not help fuel economy. I guess I should move downhill. Better yet, move next door to my job.
Monday, November 05, 2007
Stoplights revisited
I get frustrated when I'm cruising down a major thoroughfare at the speed limit on cruise control, say at 40 m.p.h. and the light turns yellow at a point that forces me to stop. Often, a lot of cars behind and in front of me will also have to stop and a single car will pull out from the cross street. Or I'll stop and there's nobody at the light on the cross street. What a waste!
So, it's frustrating, it loses time for me (and others of course), and it does waste fuel. But how much? And if we could figure out a way to eliminate them altogether, what could be saved? Sounds like a time for estimates and calculations since I can't find figures on how many stoplights are stopped at each day. I've repeatedly mentioned Fermi and so-called Fermi problems where plausible estimates are made. I'll give it a try.
Fuel is wasted in two ways at a stop light. First, the kinetic energy at speed is wasted, though the waste from this can be minimized by utilizing coasting to a stop. While your kinetic energy still goes to zero, you use less gas in getting there. But you still have to extract the potential energy from the gas to change to kinetic energy in getting back to speed. Then, you waste fuel idling at the light. I mitigate this to an extent by shutting off the engine at some long lights (the efficacy of this is controversial and the subject of future experimentation). But I'll ignore that technique for this analysis.
I'll calculate figures for what I think are average cars, drivers, and routes. I'll figure a 3000 pound car (including fuel and payload)and accelerating to 32 m.p.h. (my typical average speed over a tankful). I estimate that the average driver stops at 12 stoplights each day (is this high?) and spends 45 seconds at each. Finally, I'll estimate that an average car burns 0.35 gallons of fuel per hour at idle.
Using these numbers, I have to add 139,350 joules of kinetic energy to get the vehicle up to speed. This means I need to burn about 557,400 joules worth of gasoline, about 0.00446 gallons to add back this lost energy (since I have to burn four joules worth of gasoline to get a joule of useful work, with the 25% efficiency of the engine). And 45 seconds of idling at 0.35 gallons per hour burns 0.004375 gallons of fuel. I'll add another 0.00097 gallons for the fuel used during the coast to a stop. Thus, as an approximation, a single stoplight will waste about 0.009805 gallons of fuel. In a day of 12 stoplight encounters, this is 0.11766 gallons.
Now, I'll figure about 125,000,000 people do this in a day, for a burn of 14,707,500 gallons nationwide, representing $44M. At 19 gallons of gasoline in a barrel of oil, this is represents the gasoline in 774,000 barrels of oil. Of course, the other 25 gallons of oil are used, so all of this wouldn't be saved. Figure 1/2 of this, or 387,000 barrels. This is about 1.8% of our daily oil use.
Of course, it's not possible to have no traffic lights, so if proper sequencing and traffic management logic could reduce stops at lights by a third, 0.6% of our oil use might be saved. And the carbon in a gallon will combine in the engine with atmospheric oxygen to create about 19 pounds of carbon dioxide, so this would save 139,700 tons of CO2 per day.
For me, adjusting the figures to reflect my vehicle, I waste about 0.195 gallons per day at an approximate cost of $0.59. A little under a nickel per light. In a year, this is about $213. Not a fortune, obviously. In fact, my time at the lights is worth considerably more (depending on whom you ask). And, as above, it's impossible to live in a world with no traffic signals, so reducing my stops at lights by a third would save me about $71. Again, not a huge amount of money. But, if asked, I'd rather have $71. than not have it.
So, it's frustrating, it loses time for me (and others of course), and it does waste fuel. But how much? And if we could figure out a way to eliminate them altogether, what could be saved? Sounds like a time for estimates and calculations since I can't find figures on how many stoplights are stopped at each day. I've repeatedly mentioned Fermi and so-called Fermi problems where plausible estimates are made. I'll give it a try.
Fuel is wasted in two ways at a stop light. First, the kinetic energy at speed is wasted, though the waste from this can be minimized by utilizing coasting to a stop. While your kinetic energy still goes to zero, you use less gas in getting there. But you still have to extract the potential energy from the gas to change to kinetic energy in getting back to speed. Then, you waste fuel idling at the light. I mitigate this to an extent by shutting off the engine at some long lights (the efficacy of this is controversial and the subject of future experimentation). But I'll ignore that technique for this analysis.
I'll calculate figures for what I think are average cars, drivers, and routes. I'll figure a 3000 pound car (including fuel and payload)and accelerating to 32 m.p.h. (my typical average speed over a tankful). I estimate that the average driver stops at 12 stoplights each day (is this high?) and spends 45 seconds at each. Finally, I'll estimate that an average car burns 0.35 gallons of fuel per hour at idle.
Using these numbers, I have to add 139,350 joules of kinetic energy to get the vehicle up to speed. This means I need to burn about 557,400 joules worth of gasoline, about 0.00446 gallons to add back this lost energy (since I have to burn four joules worth of gasoline to get a joule of useful work, with the 25% efficiency of the engine). And 45 seconds of idling at 0.35 gallons per hour burns 0.004375 gallons of fuel. I'll add another 0.00097 gallons for the fuel used during the coast to a stop. Thus, as an approximation, a single stoplight will waste about 0.009805 gallons of fuel. In a day of 12 stoplight encounters, this is 0.11766 gallons.
Now, I'll figure about 125,000,000 people do this in a day, for a burn of 14,707,500 gallons nationwide, representing $44M. At 19 gallons of gasoline in a barrel of oil, this is represents the gasoline in 774,000 barrels of oil. Of course, the other 25 gallons of oil are used, so all of this wouldn't be saved. Figure 1/2 of this, or 387,000 barrels. This is about 1.8% of our daily oil use.
Of course, it's not possible to have no traffic lights, so if proper sequencing and traffic management logic could reduce stops at lights by a third, 0.6% of our oil use might be saved. And the carbon in a gallon will combine in the engine with atmospheric oxygen to create about 19 pounds of carbon dioxide, so this would save 139,700 tons of CO2 per day.
For me, adjusting the figures to reflect my vehicle, I waste about 0.195 gallons per day at an approximate cost of $0.59. A little under a nickel per light. In a year, this is about $213. Not a fortune, obviously. In fact, my time at the lights is worth considerably more (depending on whom you ask). And, as above, it's impossible to live in a world with no traffic signals, so reducing my stops at lights by a third would save me about $71. Again, not a huge amount of money. But, if asked, I'd rather have $71. than not have it.
Sunday, October 21, 2007
Headwinds
I live in Southern California, and we experience a phenomenon known as "Santa Ana Winds." These winds can literally reach hurricane speeds, I heard that a gust reached 108 m.p.h. today. These winds are invariably extremely dry and typically result in a rash of wildfires. Such has been the case today.
I was driving back to my house from Lakewood, an easterly trip down the 91 freeway. Santa Ana Winds originate in the Great Basin and thus are typically northeasterly. As I tooled down the freeway at my usual 55 m.p.h., I noted sand, pebbles, leaves, etc. blowing into my windshield as my car experienced significant buffeting. Looking at my miles per gallon display, on a level stretch where I expect to see 21.5 m.p.g. I noted 17.2 m.p.g. I had heard that the sustained winds in this area were on the order of 30 to 40 m.p.h. with possibly something like a 22 to 29 m.p.h. headwind component (it was off my nose by maybe 45 degrees), and so presumably that's the sort of gas mileage I could expect in the range of 80 m.p.h. (using the average of 22 and 29 as the headwind component).
Needless to say, I wasn't pleased but I wasn't willing to slow down to, oh, say, 30 m.p.h. to attempt to save fuel. Even my compulsiveness has limits. Besides, I didn't want a crash or a ticket. I've been pulled over for driving 55 m.p.h. in the right lane. Though the officer wouldn't say why he pulled me over, I'm sure he thought I'd been drinking (I've been sober for 28 years) and that I was trying to avoid being pulled over. He didn't even ask for my license and registration, he just shined his light in my eyes, told me to drive carefully, and left.
So what's to be learned from this headwind experience? There's not much to be done about it, but I can at least plug the numbers into my fuel consumption versus speed equation and see if they fit. Maybe my mileage gauge can serve double duty as an anemometer.
I was driving back to my house from Lakewood, an easterly trip down the 91 freeway. Santa Ana Winds originate in the Great Basin and thus are typically northeasterly. As I tooled down the freeway at my usual 55 m.p.h., I noted sand, pebbles, leaves, etc. blowing into my windshield as my car experienced significant buffeting. Looking at my miles per gallon display, on a level stretch where I expect to see 21.5 m.p.g. I noted 17.2 m.p.g. I had heard that the sustained winds in this area were on the order of 30 to 40 m.p.h. with possibly something like a 22 to 29 m.p.h. headwind component (it was off my nose by maybe 45 degrees), and so presumably that's the sort of gas mileage I could expect in the range of 80 m.p.h. (using the average of 22 and 29 as the headwind component).
Needless to say, I wasn't pleased but I wasn't willing to slow down to, oh, say, 30 m.p.h. to attempt to save fuel. Even my compulsiveness has limits. Besides, I didn't want a crash or a ticket. I've been pulled over for driving 55 m.p.h. in the right lane. Though the officer wouldn't say why he pulled me over, I'm sure he thought I'd been drinking (I've been sober for 28 years) and that I was trying to avoid being pulled over. He didn't even ask for my license and registration, he just shined his light in my eyes, told me to drive carefully, and left.
So what's to be learned from this headwind experience? There's not much to be done about it, but I can at least plug the numbers into my fuel consumption versus speed equation and see if they fit. Maybe my mileage gauge can serve double duty as an anemometer.
Sunday, October 14, 2007
More on A/C
With the Scan Gauge 2 I can find out a lot about what my engine is doing. I have it set to provide a continuous display of speed (it's about 2 m.p.h. slower than the dashboard speedometer display), r.p.m., instant mileage, and absolute manifold pressure. The manifold pressure is a very sensitive indication of throttle position, since throttling is accomplished by restricting the flow of air through the throttle body.
I've found a few stretches of freeway where it seems like the road is level, or at least its slope is constant (constant slope will suffice for this). Thus, with cruise control on, manifold pressure will remain quite constant on these stretches. This is an ideal time to experiment with turning the air conditioning on and off to see if there is an effect on manifold pressure, indicating that throttle position is increased in order to operate the compressor while still maintaining the selected speed.
So what happens? Well, the manifold pressure increases by approximately 0.4 p.s.i., typically from 9.1 p.s.i. to 9.5 p.s.i. I found this to be a consistent and repeatable result. What does it mean in terms of fuel consumption? I can run a few calculations and come up with a number, but I'm not extremely confident in the accuracy because the indications on the instant gas mileage display are not as dramatic, consistent, or repeatable.
But let's proceed anyway. PV=nRT in an ideal gas, we'll assume (inaccurately) that that's what we have. Since, for a given length of time the volume, V, and the temperature, T, are fixed, and R is the universal gas constant and thus never changes, a change in P means that n, the quantity of the gas (number of moles), must change by the same proportion. A change from 9.1 p.s.i. to 9.5 p.s.i. represents an increase of about 4.4%, so fuel consumption should increase by a similar amount. Since I'm typically looking at about 21.7 m.p.g. or so, I should see a decrease to something like 20.8 m.p.g. It doesn't seem like I see this much of a decrease, but I'm going to be doing some more checking.
In another post I determined the LR3 uses something like 24.5 horsepower to cruise on a level highway at 55 m.p.h. Since burning fuel provides this horsepower, the additional fuel burn should reflect the increased power required to run the air conditioner. How much power? It works out to be just a tiny bit over 1 horsepower, and as I concluded in my previous post on air conditioning, I find that to be a number that squares nicely with my intuition.
I've found a few stretches of freeway where it seems like the road is level, or at least its slope is constant (constant slope will suffice for this). Thus, with cruise control on, manifold pressure will remain quite constant on these stretches. This is an ideal time to experiment with turning the air conditioning on and off to see if there is an effect on manifold pressure, indicating that throttle position is increased in order to operate the compressor while still maintaining the selected speed.
So what happens? Well, the manifold pressure increases by approximately 0.4 p.s.i., typically from 9.1 p.s.i. to 9.5 p.s.i. I found this to be a consistent and repeatable result. What does it mean in terms of fuel consumption? I can run a few calculations and come up with a number, but I'm not extremely confident in the accuracy because the indications on the instant gas mileage display are not as dramatic, consistent, or repeatable.
But let's proceed anyway. PV=nRT in an ideal gas, we'll assume (inaccurately) that that's what we have. Since, for a given length of time the volume, V, and the temperature, T, are fixed, and R is the universal gas constant and thus never changes, a change in P means that n, the quantity of the gas (number of moles), must change by the same proportion. A change from 9.1 p.s.i. to 9.5 p.s.i. represents an increase of about 4.4%, so fuel consumption should increase by a similar amount. Since I'm typically looking at about 21.7 m.p.g. or so, I should see a decrease to something like 20.8 m.p.g. It doesn't seem like I see this much of a decrease, but I'm going to be doing some more checking.
In another post I determined the LR3 uses something like 24.5 horsepower to cruise on a level highway at 55 m.p.h. Since burning fuel provides this horsepower, the additional fuel burn should reflect the increased power required to run the air conditioner. How much power? It works out to be just a tiny bit over 1 horsepower, and as I concluded in my previous post on air conditioning, I find that to be a number that squares nicely with my intuition.
Tire pressure and the last 1%
Regular followers of my blog (mythical creatures though they might be) will have noted that I have compulsive tendencies. This character trait has expressed itself in various ways through my life, some destructive and others not. I consider my pursuit of maximum mileage from gasoline in my vehicle to be in the latter category. For that reason, I'm glad to continue my activities and analysis in this area.
I've had my Land Rover LR3 HSE for just shy of a year (324 days to be precise). I haven't spent a lot of time checking tire pressure, how important might this be? Various sites (see no. 4 here for example) give percentages of 2% to 4% as the excess consumption caused by under-inflation. Edmunds conducted some testing of various "tips" to save fuel, reported in a column entitled "We Test the Tips." Tire pressure is number 5 in their list of tested tips. They were unable to find consistent savings, though they did find what they termed "modest savings" in two vehicles.
What about the physics? Well, it's quite a complex topic to solve analytically, but I utilized a tool called "Dimensional Analysis" to make an approach to the problem. I concluded that rolling resistance is inversely proportional to the square root of tire pressure. This would mean that there might be approximately a 5% difference between overfilling by 2 p.s.i. versus being under-inflated by 4 p.s.i. Keep in mind that rolling resistance is only one of the external forces acting on the vehicle and that it decreases in relative importance as speed increases, since aerodynamic drag increases with the square of speed. Interestingly, tire rolling resistance is independent of vehicle speed, at least insofar as the depth of the analysis I performed.
So at highway speeds, it's likely that an increase in rolling resistance of 5% might contribute about a 2% increase to overall resistive forces, exactly in line with what many of the fuel saving sites indicate. I'd better get that gauge out of the glove box.
I've had my Land Rover LR3 HSE for just shy of a year (324 days to be precise). I haven't spent a lot of time checking tire pressure, how important might this be? Various sites (see no. 4 here for example) give percentages of 2% to 4% as the excess consumption caused by under-inflation. Edmunds conducted some testing of various "tips" to save fuel, reported in a column entitled "We Test the Tips." Tire pressure is number 5 in their list of tested tips. They were unable to find consistent savings, though they did find what they termed "modest savings" in two vehicles.
What about the physics? Well, it's quite a complex topic to solve analytically, but I utilized a tool called "Dimensional Analysis" to make an approach to the problem. I concluded that rolling resistance is inversely proportional to the square root of tire pressure. This would mean that there might be approximately a 5% difference between overfilling by 2 p.s.i. versus being under-inflated by 4 p.s.i. Keep in mind that rolling resistance is only one of the external forces acting on the vehicle and that it decreases in relative importance as speed increases, since aerodynamic drag increases with the square of speed. Interestingly, tire rolling resistance is independent of vehicle speed, at least insofar as the depth of the analysis I performed.
So at highway speeds, it's likely that an increase in rolling resistance of 5% might contribute about a 2% increase to overall resistive forces, exactly in line with what many of the fuel saving sites indicate. I'd better get that gauge out of the glove box.
Sunday, September 30, 2007
Bottled water
So... I'm walking into my local Von's grocery store. Outside on the sidewalk, on my left is a 6' wide by 8' long by 5' high display of 24-count packages of bottled water. On my right, I see a similarly sized display of another brand of bottled water. When I check out, I notice a "sale" display of Propel Fitness Water. It's being sold for two 8-count packages with 20 fluid ounces of fitness water for $10. I burst out laughing, much to the dismay of the clerk and some other customers. That's $4/gallon for water with a little vitamins thrown in. It's on sale from $5.60 per gallon. And in one way, it is a bargain. Evian is close to $7 per gallon.
Well. I really like water. It's far and away my favorite drink. I drink a lot of it. And I drink it right out of the tap, from the same source (city water) from which a lot of these purveyors of boutique water acquire the elixir. Now and again there's a source of tap water with a small odd taste, but that's quite rare. Our refrigerator at the house and the one at my company have filters. What would possess someone to pay a third more for water than they pay for gasoline? (To be fair, it looks like Evian really is imported from France. That makes it even more decisively stupid in my opinion.)
I often say that if you were to go back in time and tell someone from, oh, say, 1950 that in 57 years water would be put in small bottles and sold at stores for twice the price of gasoline they'd lock you up. The inefficiency and silliness of this water craze is hard to put into words. To draw water from a city supply, filter it, put it in plastic bottles, ship it to stores and sell it is an incredible waste. Then it's drunk and the bottle discarded or recycled using more energy. Well, I'm not going to say it should be outlawed, but my Lord, how can we have hope when such insanity prevails?
Anywhere in the United States, one can turn on the tap and receive tested, safe water for less than 1 penny per gallon. In some cases, way less. So Evian at the equivalent of $7/gallon or Propel at $4/gallon is simply ludicrous. The energy used in plastic, the transportation, etc. only makes it that much worse. When will it end?
Well. I really like water. It's far and away my favorite drink. I drink a lot of it. And I drink it right out of the tap, from the same source (city water) from which a lot of these purveyors of boutique water acquire the elixir. Now and again there's a source of tap water with a small odd taste, but that's quite rare. Our refrigerator at the house and the one at my company have filters. What would possess someone to pay a third more for water than they pay for gasoline? (To be fair, it looks like Evian really is imported from France. That makes it even more decisively stupid in my opinion.)
I often say that if you were to go back in time and tell someone from, oh, say, 1950 that in 57 years water would be put in small bottles and sold at stores for twice the price of gasoline they'd lock you up. The inefficiency and silliness of this water craze is hard to put into words. To draw water from a city supply, filter it, put it in plastic bottles, ship it to stores and sell it is an incredible waste. Then it's drunk and the bottle discarded or recycled using more energy. Well, I'm not going to say it should be outlawed, but my Lord, how can we have hope when such insanity prevails?
Anywhere in the United States, one can turn on the tap and receive tested, safe water for less than 1 penny per gallon. In some cases, way less. So Evian at the equivalent of $7/gallon or Propel at $4/gallon is simply ludicrous. The energy used in plastic, the transportation, etc. only makes it that much worse. When will it end?
Data and Statistics
I've collected data on the fuel consumption of my LR3 HSE since I purchased it in November of 2006. I've missed a couple of fill ups and a few miles when my wife has used it when I've been out of town, but by and large it's a pretty complete data set.
I've driven the vehicle in a way that most people would consider normal in terms of speed, acceleration, behavior at lights and on hills, etc. and I've more recently driven it in a way that most would regard as extreme with respect to such matters. It's obvious on the surface that my fuel economizing techniques are effective, I need only look at the graphs. But what do the statistics say?
I keep track of mileage at the most recent fill up, as well as three tank, five tank, and ten tank moving average. I track the standard deviation of the mileage (separately for before and after resumption of fuel economy maximization). The "before" data consists of 35 points, the "after" of 21 points. Surprisingly, the standard deviation of the "before" data is 0.66 m.p.g., that of the "after" is 1.20 m.p.g.
Standard deviation is a measure of "central tendency," that is, of the tendency of a data set to be clustered closely to the mean (the mathematician or statistician's term for average), or scattered far from the mean. For a so-called "normally distributed" population (that is, a population that when plotted exhibits the classic "bell curve"), about 68% of the data points will lie within plus or minus one standard deviation of the mean, about 95% within two standard deviations.
We're actually looking at an experiment here though, the question is how accurately does the mean of my mileage calculations reflect the actual gas mileage I've achieved? What we're looking for is the standard error of the mean. It's the standard deviation of the population (as computed above, itself an estimate) divided by the square root of the sample size. So, for the pre-economizing driving it's 0.66/sqrt(35)=0.11. For the post-economizing driving, it's 1.20/sqrt(21)=0.26. This latter number means the true mean gas mileage for this driving methodology, vehicle, and driving regime has about a 95% probability of being within 19.61 +/- 2*0.26 m.p.g. Or, there's about a 5% chance that the actual population mileage is outside of this range, that is, there's a 2 1/2% chance it's less than 19.09 m.p.g. and a 2 1/2% chance it's greater than 20.13 m.p.g.
This is far higher than the EPA estimate, and the graphs of my mileage show the improvements leveling off. Well, I can probably begin to make deductions based on the data I have regarding what can be done.
I've driven the vehicle in a way that most people would consider normal in terms of speed, acceleration, behavior at lights and on hills, etc. and I've more recently driven it in a way that most would regard as extreme with respect to such matters. It's obvious on the surface that my fuel economizing techniques are effective, I need only look at the graphs. But what do the statistics say?
I keep track of mileage at the most recent fill up, as well as three tank, five tank, and ten tank moving average. I track the standard deviation of the mileage (separately for before and after resumption of fuel economy maximization). The "before" data consists of 35 points, the "after" of 21 points. Surprisingly, the standard deviation of the "before" data is 0.66 m.p.g., that of the "after" is 1.20 m.p.g.
Standard deviation is a measure of "central tendency," that is, of the tendency of a data set to be clustered closely to the mean (the mathematician or statistician's term for average), or scattered far from the mean. For a so-called "normally distributed" population (that is, a population that when plotted exhibits the classic "bell curve"), about 68% of the data points will lie within plus or minus one standard deviation of the mean, about 95% within two standard deviations.
We're actually looking at an experiment here though, the question is how accurately does the mean of my mileage calculations reflect the actual gas mileage I've achieved? What we're looking for is the standard error of the mean. It's the standard deviation of the population (as computed above, itself an estimate) divided by the square root of the sample size. So, for the pre-economizing driving it's 0.66/sqrt(35)=0.11. For the post-economizing driving, it's 1.20/sqrt(21)=0.26. This latter number means the true mean gas mileage for this driving methodology, vehicle, and driving regime has about a 95% probability of being within 19.61 +/- 2*0.26 m.p.g. Or, there's about a 5% chance that the actual population mileage is outside of this range, that is, there's a 2 1/2% chance it's less than 19.09 m.p.g. and a 2 1/2% chance it's greater than 20.13 m.p.g.
This is far higher than the EPA estimate, and the graphs of my mileage show the improvements leveling off. Well, I can probably begin to make deductions based on the data I have regarding what can be done.
Behind the Power Curve
As I've mentioned previously, I'm a pilot. There's a concept in aviation called being "behind the power curve." It's a situation wherein induced drag caused by a high angle of attack means that going slower requires more rather than less power. The only way out is to lower the nose.
I've also mentioned that I'm philosophically aligned with libertarianism (small letter l). My core beliefs involve personal choice, personal responsibility, freedom, and right to privacy. Thus, I don't typically look to government to solve societal problems. However, I think that it's possible that we've reached a situation analogous to being behind the power curve, where it's going to take more unified and possibly directed action to get through the next few years without the societal equivalent of an aerodynamic stall.
What I mean is that the changes in infrastructure and industry that will be required to succeed in the establishment of a new paradigm for energy conversion have a huge energy requirement of their own. This need becomes more and more difficult to supply in light of the (possible) passing of so-called "peak oil" and the ever increasing demands on fossil fuel from the developing nations as they compete to achieve what we in America regard as (to paraphrase Dick Cheney) our non-negotiable birthright to the American lifestyle.
I love the American lifestyle of flat screen TV's (we have two), a vehicle for everyone of driving age (we have three for two people), a nice house (four bedrooms for four people), a swimming pool, and my Piper Saratoga. So what am I doing talking about saving energy and government action? And more poignantly, how do I reconcile this lifestyle of profligate energy expenditure with my attempts to squeeze a few extra miles per tank full from what is, after all, a fuel-guzzling, oversized SUV?
In a way, this is the reason that I'm afraid governments will need to step in. I have these things and live this way because I can and I like it. There are millions more like me. By the time the free market makes it impossible for me to continue to live this way, it may well be too late to matter. The market is very good at sending signals in some circumstances - it's certainly sending some clear signals about our trade deficit and our export of jobs that actually create things with the price of a dollar in Euros or Canadian Dollars. But the market seems ill equipped to send a signal that will cause us to take actions that will cost us in lifestyle and whose payoff is years into the future. Unfortunately and in contradiction to my philosophical inclination, I'm afraid that government intervention is the equivalent of putting the nose down.
I've also mentioned that I'm philosophically aligned with libertarianism (small letter l). My core beliefs involve personal choice, personal responsibility, freedom, and right to privacy. Thus, I don't typically look to government to solve societal problems. However, I think that it's possible that we've reached a situation analogous to being behind the power curve, where it's going to take more unified and possibly directed action to get through the next few years without the societal equivalent of an aerodynamic stall.
What I mean is that the changes in infrastructure and industry that will be required to succeed in the establishment of a new paradigm for energy conversion have a huge energy requirement of their own. This need becomes more and more difficult to supply in light of the (possible) passing of so-called "peak oil" and the ever increasing demands on fossil fuel from the developing nations as they compete to achieve what we in America regard as (to paraphrase Dick Cheney) our non-negotiable birthright to the American lifestyle.
I love the American lifestyle of flat screen TV's (we have two), a vehicle for everyone of driving age (we have three for two people), a nice house (four bedrooms for four people), a swimming pool, and my Piper Saratoga. So what am I doing talking about saving energy and government action? And more poignantly, how do I reconcile this lifestyle of profligate energy expenditure with my attempts to squeeze a few extra miles per tank full from what is, after all, a fuel-guzzling, oversized SUV?
In a way, this is the reason that I'm afraid governments will need to step in. I have these things and live this way because I can and I like it. There are millions more like me. By the time the free market makes it impossible for me to continue to live this way, it may well be too late to matter. The market is very good at sending signals in some circumstances - it's certainly sending some clear signals about our trade deficit and our export of jobs that actually create things with the price of a dollar in Euros or Canadian Dollars. But the market seems ill equipped to send a signal that will cause us to take actions that will cost us in lifestyle and whose payoff is years into the future. Unfortunately and in contradiction to my philosophical inclination, I'm afraid that government intervention is the equivalent of putting the nose down.
Sunday, September 16, 2007
The effect of "philosophy" on the interpretation of factual information
I like to listen to all viewpoints. I listen to KPFK, Pacifica Radio's Southern California outlet, for the farthest left point of view, and to KRLA, Salem Radio's Los Angeles area station, for the right point of view. The other day someone asked Michael Medved, an afternoon host on KRLA, about peak oil. Medved said "it's nonsense." Now, listening to him, one realizes he's an intelligent man and must be capable of understanding facts. What would cause him to say such a foolish thing?
I've concluded that Medved and many, many others (both on the radio and in "real life") decide what the facts must be to fit their viewpoint. They read books and articles and listen to people who will "confirm" the facts that support their philosophical beliefs. They form a self-reinforcing feedback loop of confirmation. I believe that talk radio, blogs, etc., have exacerbated this phenomenon. Thus, for example, people with a conservative outlook now believe that the peak oil phenomenon is nonsense because Medved said so, and he's a smart guy with a radio talk show.
The potential for disaster is huge. In my opinion the only chance, and it's a slim one, that we have of avoiding really very large trauma in the way we live our lives is the sort of single minded, participatory, nationwide goal-oriented behavior that we last exhibited during World War 2. As I've mentioned several times in my blog I have a libertarian orientation philosophically, but I don't see how we're going to get through this with everyone acting in his or her own enlightened self-interest. Nor do I see how growing population, growing energy use, growing "standard of living" (when measured in standard terms) can continue. And the denial of this will hasten and worsen the crash.
So, back to the question at hand. What can be done to help seemingly intelligent individuals to objectively evaluate facts rather than bend the facts to fit the way they think things "must work?" Unfortunately, I see a stronger tendency for this behavior from the conservative hosts on Salem Radio than from the liberal (actually liberal is far too weak) hosts on Pacifica. This saddens me, as I don't align myself with Pacifica's point of view in general. I'd like to feel that conservatives deal with facts, but this is not the case.
For another example, EVERY conservative host I know of is a "global warming denier." Now, I will definitely concede that there are intelligent climate scientists who argue that global warming caused by mankind's release of greenhouse gases is not yet a proven fact. There are many, many more who disagree. But Dennis Prager, Michael Medved, et al, will hear none of it. This is a sad commentary on their ability to deal with reality.
I wish peak oil were nonsense, I wish anthropogenic climate change were a myth, but as I had to learn as a child, wishing won't make it so.
I've concluded that Medved and many, many others (both on the radio and in "real life") decide what the facts must be to fit their viewpoint. They read books and articles and listen to people who will "confirm" the facts that support their philosophical beliefs. They form a self-reinforcing feedback loop of confirmation. I believe that talk radio, blogs, etc., have exacerbated this phenomenon. Thus, for example, people with a conservative outlook now believe that the peak oil phenomenon is nonsense because Medved said so, and he's a smart guy with a radio talk show.
The potential for disaster is huge. In my opinion the only chance, and it's a slim one, that we have of avoiding really very large trauma in the way we live our lives is the sort of single minded, participatory, nationwide goal-oriented behavior that we last exhibited during World War 2. As I've mentioned several times in my blog I have a libertarian orientation philosophically, but I don't see how we're going to get through this with everyone acting in his or her own enlightened self-interest. Nor do I see how growing population, growing energy use, growing "standard of living" (when measured in standard terms) can continue. And the denial of this will hasten and worsen the crash.
So, back to the question at hand. What can be done to help seemingly intelligent individuals to objectively evaluate facts rather than bend the facts to fit the way they think things "must work?" Unfortunately, I see a stronger tendency for this behavior from the conservative hosts on Salem Radio than from the liberal (actually liberal is far too weak) hosts on Pacifica. This saddens me, as I don't align myself with Pacifica's point of view in general. I'd like to feel that conservatives deal with facts, but this is not the case.
For another example, EVERY conservative host I know of is a "global warming denier." Now, I will definitely concede that there are intelligent climate scientists who argue that global warming caused by mankind's release of greenhouse gases is not yet a proven fact. There are many, many more who disagree. But Dennis Prager, Michael Medved, et al, will hear none of it. This is a sad commentary on their ability to deal with reality.
I wish peak oil were nonsense, I wish anthropogenic climate change were a myth, but as I had to learn as a child, wishing won't make it so.
Tuesday, July 24, 2007
Saving the world ..... again
As mentioned in a previous post, I've restarted my efforts to reduce fuel consumption in the LR3 by driving techniques. When I got the vehicle, I attempted to do so but had little success. Now, however, I've carried it to the next level, the most extreme to which I can safely and practically go. I've managed to get my average m.p.g. to slightly above 19.5 in my five tank moving average.
As I've opined over the last couple of posts, the fossil fuel situation is far too dire for such measures alone to save the day. And I've posted earlier estimates of how much fuel might be saved. But if I assume that what I'm doing now more accurately represents what can be done by the average driver than the extremes I achieved in the Grand Cherokee, what does that indicate can be accomplished?
My current three tank moving average of miles per gallon is at 19.55. The LR3 is rated by the EPA at 14 city, 18 highway. I estimate that 60% of my mileage is highway, 40% city, so the blended average mileage should be 0.4*14+0.6*18=16.4 m.p.g. I exceed this by about 3.15 m.p.g., or 19.2%.
As before, based on the complaints I hear and read, I assume that very few people are getting the mileage estimated for their vehicle by the EPA. I'll guess at 90%. I exceed this estimated average by 119.2/90=1.324, or 32.4%, so I use 1/1.324 or .755 (75.5%)as much fuel as the average person would in my vehicle driving my routes. If everyone did this and achieved the same results, it would be a reduction of 24.5% in transportation fuel usage in the personal vehicle sector.
According to this wonderful web site two thirds of U.S. oil use is in the transportation sector. I have read (I can't find sources right now) that half of transportation fuel use is in private (as opposed to commercial) vehicles. And about 19.5 gallons of gasoline comes from each of the 21 million barrels of oil we use daily. So of the 409,500,000 gallons of gasoline used each day, 24.5% or right at 100 million gallons could be saved. This is the gasoline from 5,145,000 barrels of oil.
Of course, the other 22 or so gallons of product from a barrel of oil aren't thrown away when gasoline is refined, so we wouldn't save that many barrels, but I estimate that well over two million barrels per day could be saved, 10% of our consumption and about 15% of our imports. Obviously, we won't achieve the chimeric goal of energy independence by these measures, but they could buy us some time. A side benefit would be the reduction of our trade deficit by over $4 billion per month.
As I've often pointed out in these articles, these savings won't come free, the payment will be in hours of time spent on the road instead of at work or with family, friends, etc. That price will seem more and more worth paying as scarcity increases and prices rise.
As I've opined over the last couple of posts, the fossil fuel situation is far too dire for such measures alone to save the day. And I've posted earlier estimates of how much fuel might be saved. But if I assume that what I'm doing now more accurately represents what can be done by the average driver than the extremes I achieved in the Grand Cherokee, what does that indicate can be accomplished?
My current three tank moving average of miles per gallon is at 19.55. The LR3 is rated by the EPA at 14 city, 18 highway. I estimate that 60% of my mileage is highway, 40% city, so the blended average mileage should be 0.4*14+0.6*18=16.4 m.p.g. I exceed this by about 3.15 m.p.g., or 19.2%.
As before, based on the complaints I hear and read, I assume that very few people are getting the mileage estimated for their vehicle by the EPA. I'll guess at 90%. I exceed this estimated average by 119.2/90=1.324, or 32.4%, so I use 1/1.324 or .755 (75.5%)as much fuel as the average person would in my vehicle driving my routes. If everyone did this and achieved the same results, it would be a reduction of 24.5% in transportation fuel usage in the personal vehicle sector.
According to this wonderful web site two thirds of U.S. oil use is in the transportation sector. I have read (I can't find sources right now) that half of transportation fuel use is in private (as opposed to commercial) vehicles. And about 19.5 gallons of gasoline comes from each of the 21 million barrels of oil we use daily. So of the 409,500,000 gallons of gasoline used each day, 24.5% or right at 100 million gallons could be saved. This is the gasoline from 5,145,000 barrels of oil.
Of course, the other 22 or so gallons of product from a barrel of oil aren't thrown away when gasoline is refined, so we wouldn't save that many barrels, but I estimate that well over two million barrels per day could be saved, 10% of our consumption and about 15% of our imports. Obviously, we won't achieve the chimeric goal of energy independence by these measures, but they could buy us some time. A side benefit would be the reduction of our trade deficit by over $4 billion per month.
As I've often pointed out in these articles, these savings won't come free, the payment will be in hours of time spent on the road instead of at work or with family, friends, etc. That price will seem more and more worth paying as scarcity increases and prices rise.
Saturday, July 21, 2007
Exponential growth versus exponential decline
I would like to direct my readers' attention to a web site created by an organization called "Negative Population Growth." As its name implies, the organization is devoted to bringing attention to and finding solutions for the problems of humankind caused by overpopulation (pretty much all the problems, as nearly as I can tell). The link above is to a presentation of exponential growth by Dr. Albert Bartlett, who has become famous in peak oil circles and rightly so.
I would direct the reader's attention to section II, subsections IV and V. These address the mathematics of exponential growth of consumption of a finite resource. Obviously, here I'm thinking of growth in energy (specifically, fossil fuel) use versus the finite total of recoverable fossil fuel resources. Dr. Bartlett presents the concept of the "exponential expiration time," a mathematical expression relating the size of a resource, the consumption rate of the resource, and the rate of growth of consumption of the resource.
While none of the numerical quantities involved (population growth, economic growth, total recoverable resources) are known precisely and the growth rates are not constant, the conclusions will hold qualitatively as long as the rates are positive and the resource is finite. Let's calculate a model scenario that doesn't even require an estimate of what is referred to in the peak oil community as "ultimately recoverable resources" or "URR."
The idea is to determine the rate at which so-called "renewable energy" production must increase to make up for a shortfall in availability of energy derived from fossil fuels. I'll make some assumptions, based on the best information at my disposal, regarding rate of growth of demand for fossil fuels, rate of decline of fossil fuel production, and the current rate of fossil fuel consumption. I'll cite the sources of data and the pertinent dates. The reader should keep in mind that experts have done these calculations with better models and more accurate information (not to mention higher IQ's) than I have at my disposal, so my results are meant only to help grasp the magnitude of the dilemma we face.
I found an absolute goldmine of data on energy consumption and production - BP (the old British Petroleum) has a downloadable excel spreadsheet that has a spectacular amount of information. I utilized it to find a trend line for worldwide primary energy consumption and determined that, based on data from 1965 through 2006, we have a doubling time on the order of 36 years at an annual growth rate of 1.9%/year. It's certainly possible that many developed countries could moderate their growth in energy consumption, but India and China combined are exhibiting a growth rate on the order of 5% on a curve form 1965 through 2006, and represent about a third of the world's population. It doesn't look good on the consumption side.
On the "production" side (in quotation marks because energy is never produced, it is only converted) the sum of oil plus natural gas production has every appearance of increasing linearly. The peak oil community contends that this curve will plateau (or has plateaued), but the data I see doesn't show it. Unfortunately, the situation is plenty grim even without the plateau. Assuming present trends continue, we must make up the shortfall between exponentially increasing consumption and linearly increasing production with alternative sources of primary energy (hydroelectric, wind, solar, geothermal, tidal, nuclear, etc).
This gap increases exponentially as well, and though energy production through means other than fossil fuels also is increasing exponentially, it is not doing so at a rate that will enable the shortfall to be overcome. I estimate that, in 2010, the shortfall will be on the order of 500 MTOE (million tonnes oil equivalent). In fact, my crude estimates and calculations indicate that alternative sources will be required to be equal to fossil fuel sources in about 2026. If, that is, the plateau and decline don't happen. A mighty big if.
Further, it must be noted that this quick estimate takes no account of the myriad other fossil fuel "sinks" such as plastic products, fertilizer, pharmaceutical products, etc. I believe that the time has come, and possibly gone, for a radical restructuring of how we live our lives. Every assumption and simplification I've made has underestimated the magnitude of the crisis (no other uses of fossil fuel, continuing increase in primary energy production, etc.) I'm neither a socialist nor a utopian, however, every trend I've analyzed indicates that we're whistling past the graveyard and that only the most extreme measures will suffice to avoid catastrophe.
And driving more slowly in an LR3 is not going to get it done.
I would direct the reader's attention to section II, subsections IV and V. These address the mathematics of exponential growth of consumption of a finite resource. Obviously, here I'm thinking of growth in energy (specifically, fossil fuel) use versus the finite total of recoverable fossil fuel resources. Dr. Bartlett presents the concept of the "exponential expiration time," a mathematical expression relating the size of a resource, the consumption rate of the resource, and the rate of growth of consumption of the resource.
While none of the numerical quantities involved (population growth, economic growth, total recoverable resources) are known precisely and the growth rates are not constant, the conclusions will hold qualitatively as long as the rates are positive and the resource is finite. Let's calculate a model scenario that doesn't even require an estimate of what is referred to in the peak oil community as "ultimately recoverable resources" or "URR."
The idea is to determine the rate at which so-called "renewable energy" production must increase to make up for a shortfall in availability of energy derived from fossil fuels. I'll make some assumptions, based on the best information at my disposal, regarding rate of growth of demand for fossil fuels, rate of decline of fossil fuel production, and the current rate of fossil fuel consumption. I'll cite the sources of data and the pertinent dates. The reader should keep in mind that experts have done these calculations with better models and more accurate information (not to mention higher IQ's) than I have at my disposal, so my results are meant only to help grasp the magnitude of the dilemma we face.
I found an absolute goldmine of data on energy consumption and production - BP (the old British Petroleum) has a downloadable excel spreadsheet that has a spectacular amount of information. I utilized it to find a trend line for worldwide primary energy consumption and determined that, based on data from 1965 through 2006, we have a doubling time on the order of 36 years at an annual growth rate of 1.9%/year. It's certainly possible that many developed countries could moderate their growth in energy consumption, but India and China combined are exhibiting a growth rate on the order of 5% on a curve form 1965 through 2006, and represent about a third of the world's population. It doesn't look good on the consumption side.
On the "production" side (in quotation marks because energy is never produced, it is only converted) the sum of oil plus natural gas production has every appearance of increasing linearly. The peak oil community contends that this curve will plateau (or has plateaued), but the data I see doesn't show it. Unfortunately, the situation is plenty grim even without the plateau. Assuming present trends continue, we must make up the shortfall between exponentially increasing consumption and linearly increasing production with alternative sources of primary energy (hydroelectric, wind, solar, geothermal, tidal, nuclear, etc).
This gap increases exponentially as well, and though energy production through means other than fossil fuels also is increasing exponentially, it is not doing so at a rate that will enable the shortfall to be overcome. I estimate that, in 2010, the shortfall will be on the order of 500 MTOE (million tonnes oil equivalent). In fact, my crude estimates and calculations indicate that alternative sources will be required to be equal to fossil fuel sources in about 2026. If, that is, the plateau and decline don't happen. A mighty big if.
Further, it must be noted that this quick estimate takes no account of the myriad other fossil fuel "sinks" such as plastic products, fertilizer, pharmaceutical products, etc. I believe that the time has come, and possibly gone, for a radical restructuring of how we live our lives. Every assumption and simplification I've made has underestimated the magnitude of the crisis (no other uses of fossil fuel, continuing increase in primary energy production, etc.) I'm neither a socialist nor a utopian, however, every trend I've analyzed indicates that we're whistling past the graveyard and that only the most extreme measures will suffice to avoid catastrophe.
And driving more slowly in an LR3 is not going to get it done.
Y2K was an epic disaster after all
You all remember the approach to Y2K don't you? There were books, magazine articles, web sites, etc. devoted to the inevitability of system wide disaster to be caused by the Y2K bug and to the consequences thereof. Then disaster struck - Y2K came and went and nothing of any consequence happened. Now, there are many explanations. Chief among them is that hundreds of billions of dollars and millions of person-hours were spent and that that expenditure, which for some reason was invisible to the average person, saved us. Therein lies the true disaster.
The Y2K non-event has persuaded many people that predictions of imminent threats to our entire society and way of life are merely the yammerings of wolf-crying doom sayers. In some cases, that may be true. Unfortunately, when it comes to our ability to fuel our society on petroleum products, it is false. This threat is real, and dire consequences are, in fact, unavoidable. The problem is that warnings fall on deaf ears, in part because the average person thinks "yeah yeah, I've heard it all before. They said the same thing about Y2K." One would like to think that a brief application of common sense would cause people to realize that exponentially increasing consumption of a finite resource is a dead-end street, but that brief application is missing.
I live in a so-called "McMansion" (a 2500 square foot four bedroom house) in Anaheim Hills, and as extensively noted in this blog, I drive a 60 mile round trip to work in a segment (inspection and materials testing) of an industry (construction) that will surely go away in the tsunami of economic dislocation caused by the unavailability of imported fossil fuels to "feed the beast." Further, much of my net worth is tied up in the equity in my house and my equity in the company for which I work and in which I am a partner. My vulnerability is huge, I'm a perfect example of what won't work.
The simultaneous trends of exponentially increasing consumption and the peaking of production of fossil fuels would be bad enough. However, quoting the infomercials, "but wait, there's more!" As explained here, as exporting countries' fuel resources begin to suffer the effects of depletion while their citizens demand the things we assume we will always have here (cars, air conditioning, etc.), those countries will divert exports to internal consumption. So even if production doesn't slide as quickly as some predict, oil available for export to the U.S. will decline steeply in the very near future. To call the consequences dire is to understate them dramatically.
Thus, my playing with a Land Rover LR3 to see if I can coax 20 m.p.g. out of it is truly a hobby and almost irrelevant to the fossil fuel situation we face. As far off as James Howard Kunstler was in his Y2K predictions and as bombastic as he is in his prose, I'm afraid that this time he's right. So the true disaster of Y2K was that it blinded many of us to the real doomsday scenario we now face, and prevents us from taking any meaningful steps to mitigate the inevitable tragedy ahead.
The Y2K non-event has persuaded many people that predictions of imminent threats to our entire society and way of life are merely the yammerings of wolf-crying doom sayers. In some cases, that may be true. Unfortunately, when it comes to our ability to fuel our society on petroleum products, it is false. This threat is real, and dire consequences are, in fact, unavoidable. The problem is that warnings fall on deaf ears, in part because the average person thinks "yeah yeah, I've heard it all before. They said the same thing about Y2K." One would like to think that a brief application of common sense would cause people to realize that exponentially increasing consumption of a finite resource is a dead-end street, but that brief application is missing.
I live in a so-called "McMansion" (a 2500 square foot four bedroom house) in Anaheim Hills, and as extensively noted in this blog, I drive a 60 mile round trip to work in a segment (inspection and materials testing) of an industry (construction) that will surely go away in the tsunami of economic dislocation caused by the unavailability of imported fossil fuels to "feed the beast." Further, much of my net worth is tied up in the equity in my house and my equity in the company for which I work and in which I am a partner. My vulnerability is huge, I'm a perfect example of what won't work.
The simultaneous trends of exponentially increasing consumption and the peaking of production of fossil fuels would be bad enough. However, quoting the infomercials, "but wait, there's more!" As explained here, as exporting countries' fuel resources begin to suffer the effects of depletion while their citizens demand the things we assume we will always have here (cars, air conditioning, etc.), those countries will divert exports to internal consumption. So even if production doesn't slide as quickly as some predict, oil available for export to the U.S. will decline steeply in the very near future. To call the consequences dire is to understate them dramatically.
Thus, my playing with a Land Rover LR3 to see if I can coax 20 m.p.g. out of it is truly a hobby and almost irrelevant to the fossil fuel situation we face. As far off as James Howard Kunstler was in his Y2K predictions and as bombastic as he is in his prose, I'm afraid that this time he's right. So the true disaster of Y2K was that it blinded many of us to the real doomsday scenario we now face, and prevents us from taking any meaningful steps to mitigate the inevitable tragedy ahead.
Sunday, July 15, 2007
Alternative transport redux
In a previous post I discussed the benefits of using an electric scooter for the bulk of my commuting to and from work. The analysis there was based on my fuel use in the Jeep Grand Cherokee Limited I had when I started this blog. It should be even more beneficial with the Land Rover LR3 HSE that I'm driving now, since the LR3 achieves about 4 m.p.g. less than the Grand Cherokee.
Further, there's a scooter available from Zap!, called the Zapino that, with their optional 60 volt 40 amp-hour battery, claims a range of "up to 65 miles." My commute, as I would have to ride it on surface streets, is 25.57 miles (according to Google Earth) so, in theory, I could make the round trip on a single charge. I wouldn't do it, because the very last part of my trip home is up a very severe hill. I wouldn't want to try it on a dwindling charge. But if I charge it at work, my hope is that it would have sufficient charge remaining to take me up the hill to my house.
There are various factors to consider, even if I stipulate (I've been around lawyers too much lately) that the Zapino is well-built and reliable and will climb the hill at the end of a workday. Most importantly, I need to know the financial impact (the Zapino retails with the standard battery for $3,495, I can't find the price of the optional battery I'd need), and how much time my commute would take.
I can run the route I'd have to take on the scooter but I think it would be foolish to do it in the LR3 at the speed to which I'd be limited in the scooter. So I'll estimate that it would take about 75 minutes each way. My current commute is about 40 minutes. Am I willing to spend 70 extra minutes per day commuting? I wouldn't be able to listen to books on tape or podcasts or even talk radio - such a vehicle requires close attention in city traffic. It's possible that it could be "reasonably" safe to carry a bluetooth ear piece and do limited cell phone business. In most cases, I think I'd have to pull off the road and consequently increase the commute time. It sounds like a non-starter at this point.
For the financial impact, most of the figures in my previous post can, with slight modification, be applied to the use of the Zapino in lieu of the LR3 for the bulk of my work commutes. Of course, these will only be rough estimates, but they should suffice for a "go/no-go" decision. I calculate that the Zapino should cost about $0.10/mile to operate or about $850/year for 180 commutes versus about $4,700/year to operate the LR3 for those commutes. Thus, the potential cost reduction is $3,850/year.
Combining these figures, I'd spend 210 extra hours per year to save $3,850. This means that I'd be paid at the rate of $3,850/210 or $18.33/hour. Unfortunately for my Company, my hourly rate exceeds this by a considerable margin. Thus, in order to make it attractive, I would have to regard the excess time spent on the scooter as personal time, something like a hobby. I think that, to start, it would feel that way. But that would likely get old quite quickly.
These types of tradeoffs are endemic to alternative transport, or even to adjustment of driving techniques to minimize fuel consumption. Professor Steven Dutch, whom I have cited extensively in this blog, makes a cost benefit analysis of public transportation that makes it clear why, for most people, mass transit is not a compelling choice.
Future economic considerations may change the calculus here, and in fact, may make the choice of commuting in a vehicle like the LR3 impossible at any price. Until then, I'm afraid that I just can't justify alternative transport.
Further, there's a scooter available from Zap!, called the Zapino that, with their optional 60 volt 40 amp-hour battery, claims a range of "up to 65 miles." My commute, as I would have to ride it on surface streets, is 25.57 miles (according to Google Earth) so, in theory, I could make the round trip on a single charge. I wouldn't do it, because the very last part of my trip home is up a very severe hill. I wouldn't want to try it on a dwindling charge. But if I charge it at work, my hope is that it would have sufficient charge remaining to take me up the hill to my house.
There are various factors to consider, even if I stipulate (I've been around lawyers too much lately) that the Zapino is well-built and reliable and will climb the hill at the end of a workday. Most importantly, I need to know the financial impact (the Zapino retails with the standard battery for $3,495, I can't find the price of the optional battery I'd need), and how much time my commute would take.
I can run the route I'd have to take on the scooter but I think it would be foolish to do it in the LR3 at the speed to which I'd be limited in the scooter. So I'll estimate that it would take about 75 minutes each way. My current commute is about 40 minutes. Am I willing to spend 70 extra minutes per day commuting? I wouldn't be able to listen to books on tape or podcasts or even talk radio - such a vehicle requires close attention in city traffic. It's possible that it could be "reasonably" safe to carry a bluetooth ear piece and do limited cell phone business. In most cases, I think I'd have to pull off the road and consequently increase the commute time. It sounds like a non-starter at this point.
For the financial impact, most of the figures in my previous post can, with slight modification, be applied to the use of the Zapino in lieu of the LR3 for the bulk of my work commutes. Of course, these will only be rough estimates, but they should suffice for a "go/no-go" decision. I calculate that the Zapino should cost about $0.10/mile to operate or about $850/year for 180 commutes versus about $4,700/year to operate the LR3 for those commutes. Thus, the potential cost reduction is $3,850/year.
Combining these figures, I'd spend 210 extra hours per year to save $3,850. This means that I'd be paid at the rate of $3,850/210 or $18.33/hour. Unfortunately for my Company, my hourly rate exceeds this by a considerable margin. Thus, in order to make it attractive, I would have to regard the excess time spent on the scooter as personal time, something like a hobby. I think that, to start, it would feel that way. But that would likely get old quite quickly.
These types of tradeoffs are endemic to alternative transport, or even to adjustment of driving techniques to minimize fuel consumption. Professor Steven Dutch, whom I have cited extensively in this blog, makes a cost benefit analysis of public transportation that makes it clear why, for most people, mass transit is not a compelling choice.
Future economic considerations may change the calculus here, and in fact, may make the choice of commuting in a vehicle like the LR3 impossible at any price. Until then, I'm afraid that I just can't justify alternative transport.
Friday, June 29, 2007
The practicalities of drafting
As I've mentioned previously I do some drafting of trucks to increase my gas mileage. I did some estimations and calculations, described in that post, that indicate that, done with extreme caution, it could be safe and that it should be effective. But how practical is it? It's turned out that I'm only able to find a truck to draft between 10% and 15% of the time I'm at freeway speed. Trucks are frequently going too fast for my fuel saving regime, thus leading to the question of what the break even point would be for the fuel used in speeding up to draft a fast-moving truck versus maintaining a leisurely 55 m.p.h. with no truck in front of me. More on this later.
But the fact is, there is rarely a suitable truck around when I need one. I look for trucks with the following characteristics, just based on intuition: low trailer; as square a back as possible (preferably not a milk or cement tanker); not hauling rock, dirt, etc. (no dump trucks); maintains a reasonably steady speed; doesn't do a lot of lane switching, I guess that pretty much covers the candidates. But at 55 m.p.h. I'm not doing much passing of them, so I have to wait for a truck that has the listed attributes to pass me. It is rarer than I would have guessed, though if I see a likely prospect in the rear view mirror, I can slow down to let him catch me.
So when does it pay to speed up to draft? There are two aspects to this - the fuel used in accelerating to a new speed, and the balance between the reduction in drag from being behind the truck (this would be in the density term in the drag equation) and the increase in the speed. Additionally, road loads would increase by a small amount, but I assume this to be linear, and thus the increase in road load force is compensated by the increase in distance covered.
There will be a number at which my fuel savings from reduced density (the low pressure zone behind the truck) will be overcome by the increase from the speed term, since it's squared in the drag equation. For the purposes of this post, I'll ignore the fuel used to get up to a higher speed - this fuel is used to increase the kinetic energy of the vehicle, I'll assume I can recapture this energy (though of course I can't, at least not with 100% efficiency).
I have to use the figures in my previous post on drafting to calculate the reduction in drag to attribute to the truck's wake, and calculate from there. Using my best estimate of the increase in gas mileage while drafting, from 21.5 m.p.g. to about 25 m.p.g., I can calculate that air density is decreased by about 14.0% (from about 1.16 kg/m^3 to about 0.998 kg/m^3). Again, unless I receive a huge outcry demanding the details of the mathematics involved, I'll only outline the process and give the results.
Plugging these density results into the drag equation and realizing that I want to minimize fuel/distance (gallons per mile) = energy/distance = work/distance = force * distance/distance = force, I merely need to determine when drag using the decreased density behind the truck but an increased speed exceeds drag at normal density and 55 m.p.h. As it turns out, that speed is a little over 59 m.p.h. So if I have to go faster than 59 m.p.h. to draft a truck, I will lose fuel efficiency compared to driving 55 m.p.h. in the clear.
Thus, the battle becomes one of finding a truck with all the characteristics listed above AND that is not going faster than 59 m.p.h. This has turned out to be extremely difficult. As I refine my data, I'll revisit these figures.
But the fact is, there is rarely a suitable truck around when I need one. I look for trucks with the following characteristics, just based on intuition: low trailer; as square a back as possible (preferably not a milk or cement tanker); not hauling rock, dirt, etc. (no dump trucks); maintains a reasonably steady speed; doesn't do a lot of lane switching, I guess that pretty much covers the candidates. But at 55 m.p.h. I'm not doing much passing of them, so I have to wait for a truck that has the listed attributes to pass me. It is rarer than I would have guessed, though if I see a likely prospect in the rear view mirror, I can slow down to let him catch me.
So when does it pay to speed up to draft? There are two aspects to this - the fuel used in accelerating to a new speed, and the balance between the reduction in drag from being behind the truck (this would be in the density term in the drag equation) and the increase in the speed. Additionally, road loads would increase by a small amount, but I assume this to be linear, and thus the increase in road load force is compensated by the increase in distance covered.
There will be a number at which my fuel savings from reduced density (the low pressure zone behind the truck) will be overcome by the increase from the speed term, since it's squared in the drag equation. For the purposes of this post, I'll ignore the fuel used to get up to a higher speed - this fuel is used to increase the kinetic energy of the vehicle, I'll assume I can recapture this energy (though of course I can't, at least not with 100% efficiency).
I have to use the figures in my previous post on drafting to calculate the reduction in drag to attribute to the truck's wake, and calculate from there. Using my best estimate of the increase in gas mileage while drafting, from 21.5 m.p.g. to about 25 m.p.g., I can calculate that air density is decreased by about 14.0% (from about 1.16 kg/m^3 to about 0.998 kg/m^3). Again, unless I receive a huge outcry demanding the details of the mathematics involved, I'll only outline the process and give the results.
Plugging these density results into the drag equation and realizing that I want to minimize fuel/distance (gallons per mile) = energy/distance = work/distance = force * distance/distance = force, I merely need to determine when drag using the decreased density behind the truck but an increased speed exceeds drag at normal density and 55 m.p.h. As it turns out, that speed is a little over 59 m.p.h. So if I have to go faster than 59 m.p.h. to draft a truck, I will lose fuel efficiency compared to driving 55 m.p.h. in the clear.
Thus, the battle becomes one of finding a truck with all the characteristics listed above AND that is not going faster than 59 m.p.h. This has turned out to be extremely difficult. As I refine my data, I'll revisit these figures.
Tuesday, June 26, 2007
Turning resources to refuse
I read somewhere, I don't remember where, something to the effect that "an economy is a system for turning natural resources into refuse." Obviously, that's hyperbole, but it's not completely without basis. A couple of posts back I looked at national and global energy consumption, comparing time frames and comparing countries and the world. I thought that I could pursue that a little further and see what the energy requirements are to "turn natural resources into refuse."
As I stated in the post linked above, in 2006 the United States consumed 100.41*10^15 btu, or 1.059*10^20 joules of energy. In that time, we produced 245 million tons, or 222*10^9 kilograms of "MSW," municipal solid waste. I can't find an authoritative source for total air pollution in 2006, but in 2005 the total was 141 million tons. Now, that number is on a strong downward trend, it was 188 million in 1995 and 160 million in 2000. Bearing this in mind, I'll use 136 million tons or 123*10^9 kilograms in 2006. I can't find good numbers for water pollution and liquid waste, so I'll blithely assume it's negligible. With that in mind, I'll say we produced 345*10^9 kilograms of waste. So for a start, we used 307 million joules of energy per kilogram of waste. Now, 307 million joules is the amount of energy in about 6.5 kilograms or 2.5 gallons of gasoline.
So our economy used the energy available in 6.5 kilograms of gasoline to produce a kilogram of waste. Let's be optimistic and assume that the combined efficiency of all the energy conversion processes we use is 40%. That would mean that we really needed 16.25 kilograms of gasoline or equivalent to produce a kilogram of waste. Now what does that mean? Good question. From one point of view, if our energy to waste ratio were high, it could mean we didn't waste much, that that energy went into useful things. On the other hand, if our energy to waste ratio were low, it could mean we were efficient, since it wouldn't have taken much energy to produce our byproducts. But I suspect a big number is what we'd like to see.
The complexity of the situation comes from the fact that, taken independently, we'd like to produce small amounts of waste, and we'd like to consume small amounts of energy. I think the way to get a handle on this would be to find out how much energy in joules is contained in an "average" kilogram of manufactured product. In the end, what we want is as little of our consumed energy as possible to go into things that are discarded.
As I stated in the post linked above, in 2006 the United States consumed 100.41*10^15 btu, or 1.059*10^20 joules of energy. In that time, we produced 245 million tons, or 222*10^9 kilograms of "MSW," municipal solid waste. I can't find an authoritative source for total air pollution in 2006, but in 2005 the total was 141 million tons. Now, that number is on a strong downward trend, it was 188 million in 1995 and 160 million in 2000. Bearing this in mind, I'll use 136 million tons or 123*10^9 kilograms in 2006. I can't find good numbers for water pollution and liquid waste, so I'll blithely assume it's negligible. With that in mind, I'll say we produced 345*10^9 kilograms of waste. So for a start, we used 307 million joules of energy per kilogram of waste. Now, 307 million joules is the amount of energy in about 6.5 kilograms or 2.5 gallons of gasoline.
So our economy used the energy available in 6.5 kilograms of gasoline to produce a kilogram of waste. Let's be optimistic and assume that the combined efficiency of all the energy conversion processes we use is 40%. That would mean that we really needed 16.25 kilograms of gasoline or equivalent to produce a kilogram of waste. Now what does that mean? Good question. From one point of view, if our energy to waste ratio were high, it could mean we didn't waste much, that that energy went into useful things. On the other hand, if our energy to waste ratio were low, it could mean we were efficient, since it wouldn't have taken much energy to produce our byproducts. But I suspect a big number is what we'd like to see.
The complexity of the situation comes from the fact that, taken independently, we'd like to produce small amounts of waste, and we'd like to consume small amounts of energy. I think the way to get a handle on this would be to find out how much energy in joules is contained in an "average" kilogram of manufactured product. In the end, what we want is as little of our consumed energy as possible to go into things that are discarded.
Taming the LR3
As I've mentioned repeatedly, I have had very little success in utilizing driving techniques to make a large impact on the fuel economy of the LR3. This lack of success led me down a road of trying to understand the aerodynamics of the vehicle, the specifics of the engine and transmission, and the effects of driveline friction. It's been educational, but not satisfying with respect to enabling me to goose my gas mileage.
As my brother said, "it kinda takes the fun out of it." Hence, for several months, starting around the beginning of 2007, I stopped using fuel economy maximizing techniques. I didn't go "hog wild" and floor it from the light, drive as fast as traffic would allow, etc., but I would accelerate with the traffic, drive at typical speeds, eschew coasting in neutral and turning off the engine, etc.
The last three weeks or so, however, I have renewed my efforts. I've managed to bring my three tank moving average of gas mileage from a little under 16 m.p.g. to a little under 19 m.p.g. My most recent fill-up indicated 19.37 m.p.h. The improvement is probably a result of 55 m.p.h. or slower, drafting where possible, stoplight shutdowns, and coasting with the engine off. I did most of these before, but I tried being ultra aggressive in doing them.
So fuel can be saved. The LR3 is rated by the EPA at 18 highway, 14 city. By my best estimate of the relative amounts of highway and city driving in my regime (about 60/40) the EPA thinks I should see overall mileage of 16.4 m.p.g. (0.6*18 + 0.4*14). That means that the 18.85 m.p.g. in my most recent three tank moving average is 14.9% over the weighted EPA estimate.
As a point of comparison, in the Jeep Grand Cherokee Limited in which I started this experiment, I was able to achieve about 30.6% better mileage than the weighted EPA estimate. I don't know the reason that the LR3 has only allowed me to exceed the EPA estimate by about 1/2 as great a percentage as the Grand Cherokee. It may be that the LR3, about six years newer, incorporates engine management techniques that make the vehicle more efficient when driving normally. If this is the case, I will have to assume that all manufacturers utilize these management techniques and hence reduce my estimate of the impact on national fuel consumption of universal adoption of extreme mileage enhancing driving techniques. I'll save that for another post.
I will say that I am pleased that I can exceed the 19 m.p.g. barrier, and 20 m.p.g. is in my sights.
As my brother said, "it kinda takes the fun out of it." Hence, for several months, starting around the beginning of 2007, I stopped using fuel economy maximizing techniques. I didn't go "hog wild" and floor it from the light, drive as fast as traffic would allow, etc., but I would accelerate with the traffic, drive at typical speeds, eschew coasting in neutral and turning off the engine, etc.
The last three weeks or so, however, I have renewed my efforts. I've managed to bring my three tank moving average of gas mileage from a little under 16 m.p.g. to a little under 19 m.p.g. My most recent fill-up indicated 19.37 m.p.h. The improvement is probably a result of 55 m.p.h. or slower, drafting where possible, stoplight shutdowns, and coasting with the engine off. I did most of these before, but I tried being ultra aggressive in doing them.
So fuel can be saved. The LR3 is rated by the EPA at 18 highway, 14 city. By my best estimate of the relative amounts of highway and city driving in my regime (about 60/40) the EPA thinks I should see overall mileage of 16.4 m.p.g. (0.6*18 + 0.4*14). That means that the 18.85 m.p.g. in my most recent three tank moving average is 14.9% over the weighted EPA estimate.
As a point of comparison, in the Jeep Grand Cherokee Limited in which I started this experiment, I was able to achieve about 30.6% better mileage than the weighted EPA estimate. I don't know the reason that the LR3 has only allowed me to exceed the EPA estimate by about 1/2 as great a percentage as the Grand Cherokee. It may be that the LR3, about six years newer, incorporates engine management techniques that make the vehicle more efficient when driving normally. If this is the case, I will have to assume that all manufacturers utilize these management techniques and hence reduce my estimate of the impact on national fuel consumption of universal adoption of extreme mileage enhancing driving techniques. I'll save that for another post.
I will say that I am pleased that I can exceed the 19 m.p.g. barrier, and 20 m.p.g. is in my sights.
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