My previous post dealt with the total energy required in using various means to go to the store for groceries. My conclusion was counter-intuitive, in that it appears that bicycling uses more energy than an electric scooter. Now clearly if I'm fulfilling another purpose, e.g., maintaining a level of physical activity for fitness, the energy issue may not be the deciding factor in my choice. And bicycles are cheaper than viable electric scooters.
But, speaking of price, let's focus on the cost analysis from an energy point of view. The energy used in my means of transportation should be reflected in the price I pay to use it so I'll see what each method costs. From the previous post, if I walk I'll have to buy 491 kilocalories of food to make the trip. Clearly, all kilocalories are not created equal, but I estimate that if I eat 2500 kilocalories/day and am doing so in a "not too unhealthy" way, I might spend about $7.00, or $0.0028/kilocalorie. Thus, my trip costs .0028*491=$1.37. An identical calculation for the bicycle, using the 162 kilocalories from my earlier post, results in a cost of $0.45.
For the electric scooter, I'll use 751,000 joules or 0.208 kilowatt hours (the 638,000 joules used by the trip divided by the 85% charger efficiency, i.e., this is what I pay for). This will cost me a little less than $0.03. Pretty darn cheap!
For the smart fortwo, I'll use $0.59 worth of gasoline (6 miles at 33 m.p.g. and premium fuel at $3.239/gallon) and for the Land Rover LR3 HSE, it will be $1.10.
So the cost results, surprisingly, do change the order. It's cheaper, in end user energy purchase price, to drive than to walk. This holds true even in my three ton Land Rover. Shocking indeed, but I don't see a huge error. Obviously, electricity and gasoline are commodities and food isn't so I can, to a certain extent, choose what to pay for a kilocalorie. One thing that quickly jumps out is that food is expensive! I bet no one reading was aware of this obscure fact.
Perhaps if I choose food for minimum kilocalories/dollar, I could cut the price by something like 70%. Doing that makes the trip $0.13 on the bicycle and $0.39 to walk. I think this is at least a reasonable view, the cost per kilocalorie above the minimum is for taste, convenience, "earth friendliness," etc. and not for energy. This adjustment changes the order back to a match for the total energy conversion analysis.
To recap (using minimal food cost):
Electric Scooter: $0.03
Bicycle: $0.13
Walking: $0.39
smart fortwo: $0.59
Land Rover LR3 HSE: $1.10
To recap (using food I typically buy):
Electric Scooter: $0.03
Bicycle: $0.45
smart fortwo: $0.59
Land Rover LR3 HSE: $1.10
Walking: $1.37
Sunday, August 30, 2009
Saturday, August 29, 2009
Going to the store
Hypothetical question (its hypothetical nature will be explained later): A grocery store is located 3 miles from my door with a level path. I need groceries that will fit in a single bag. How much fossil fuel is used, ALL INPUTS CONSIDERED, if I: walk; ride a bicycle; take an electric scooter; drive a smart fortwo; drive my LR3 HSE. I'll assume the two gasoline vehicles are warmed up.
As is typical, I'll be making estimates, but I doubt that the order will be wrong. Let's start with walking. Assuming I walk at 3 m.p.h., it will take 120 minutes to walk to the store and back. Using this calculator, I find that I'll convert 491 kilocalories of food energy to heat (the site calls them calories but this is incorrect). Now, it is said that 7 to 10 kilocalories of fossil fuel energy are required to produce a kilocalorie of food. I'll use 8.5, so 8.5*491=4170 kilocalories or 17.5*10^6 joules of fossil fuel energy to get me to the store and back.
How about a bicycle? Using the very nice calculator here and assuming I ride at 10 m.p.h. (faster on the way there, slower on the way back), I find I'll burn 162 kilocalories of food energy requiring 8.5*162=1377 kilocalories or 5.76*10^6 joules of fossil fuel energy.
Looking at the electric scooter, I'll use the Zapino (previously posted about here) as my representative. The optional 60 volt, 40 amp-hour Lithium battery supposedly gives it a range of "about 65 miles." Now, 60 volts at 40 amps for an hour is 8.64*10^6 joules but I would think the range would be based on, say, 80% discharge. So that means it uses 8.64*10^6*0.8/65=106,000 joules/mile and my 6 mile trip would use 638,000 joules. But wait. The charger would only be about 85% efficient and transmission of electricity is typically about 60% efficient. So I'll use 638,000/(0.85*0.6)=1.25*10^6 joules of electricity from the generating station. Are we done? No, this electricity is likely generated by a fossil fuel plant whose efficiency is on the order of 50%, so double that to 2.50*10^6 joules of primary fossil fuel energy. Finally, using an EROEI (energy return on energy invested) of 7.5:1, we multiply 2.50*10^6*8.5/7.5 to find that it requires 2.83*10^6 joules of primary fossil fuel energy in total to go to the store and back.
The smart fortwo about which I posted here? Certainly this will be city driving where the fortwo is listed by the EPA at 33 m.p.g. A nice little article singing the Tesla's praises gives me the "well to wheel" data I need. Without bothering my patient readers with the conversions and calculations, I find that the fortwo uses 28.9*10^6 joules of primary energy (including well to pump to wheel efficiency) to accomplish the mission. It should be noted that a "hypermiler" could likely do significantly better.
Finally, the LR3 HSE (with me driving it) will achieve about 17.6 m.p.g. in the city and thus uses 54.2*10^6 joules of primary energy to go to the store. So the electric scooter is the best, using about 5% of the energy of the LR3. Surprisingly, the bicycle uses twice as much energy (remember, all fuel inputs to food production are included and no distinction is made for vegetarian versus omnivorous diet, so your mileage may vary) as the scooter and walking even more. I may have to revisit the scooter yet again. And why is the question hypothetical? It's down a long and steep hill from my house to the store and, more importantly, up that long and steep hill to get back.
To recap:
Electric Scooter: 2.83*10^6 joules
Bicycle: 5.76*10^6 joules
Walking: 17.5*10^6 joules
smart fortwo: 28.9*10^6 joules
Land Rover LR3 HSE: 54.2*10^6 joules
Update: A very interesting analysis of the bicycle versus electric bicycle (scooter) energy requirements that includes life-cycle energy consideration done as a term paper is available here.
As is typical, I'll be making estimates, but I doubt that the order will be wrong. Let's start with walking. Assuming I walk at 3 m.p.h., it will take 120 minutes to walk to the store and back. Using this calculator, I find that I'll convert 491 kilocalories of food energy to heat (the site calls them calories but this is incorrect). Now, it is said that 7 to 10 kilocalories of fossil fuel energy are required to produce a kilocalorie of food. I'll use 8.5, so 8.5*491=4170 kilocalories or 17.5*10^6 joules of fossil fuel energy to get me to the store and back.
How about a bicycle? Using the very nice calculator here and assuming I ride at 10 m.p.h. (faster on the way there, slower on the way back), I find I'll burn 162 kilocalories of food energy requiring 8.5*162=1377 kilocalories or 5.76*10^6 joules of fossil fuel energy.
Looking at the electric scooter, I'll use the Zapino (previously posted about here) as my representative. The optional 60 volt, 40 amp-hour Lithium battery supposedly gives it a range of "about 65 miles." Now, 60 volts at 40 amps for an hour is 8.64*10^6 joules but I would think the range would be based on, say, 80% discharge. So that means it uses 8.64*10^6*0.8/65=106,000 joules/mile and my 6 mile trip would use 638,000 joules. But wait. The charger would only be about 85% efficient and transmission of electricity is typically about 60% efficient. So I'll use 638,000/(0.85*0.6)=1.25*10^6 joules of electricity from the generating station. Are we done? No, this electricity is likely generated by a fossil fuel plant whose efficiency is on the order of 50%, so double that to 2.50*10^6 joules of primary fossil fuel energy. Finally, using an EROEI (energy return on energy invested) of 7.5:1, we multiply 2.50*10^6*8.5/7.5 to find that it requires 2.83*10^6 joules of primary fossil fuel energy in total to go to the store and back.
The smart fortwo about which I posted here? Certainly this will be city driving where the fortwo is listed by the EPA at 33 m.p.g. A nice little article singing the Tesla's praises gives me the "well to wheel" data I need. Without bothering my patient readers with the conversions and calculations, I find that the fortwo uses 28.9*10^6 joules of primary energy (including well to pump to wheel efficiency) to accomplish the mission. It should be noted that a "hypermiler" could likely do significantly better.
Finally, the LR3 HSE (with me driving it) will achieve about 17.6 m.p.g. in the city and thus uses 54.2*10^6 joules of primary energy to go to the store. So the electric scooter is the best, using about 5% of the energy of the LR3. Surprisingly, the bicycle uses twice as much energy (remember, all fuel inputs to food production are included and no distinction is made for vegetarian versus omnivorous diet, so your mileage may vary) as the scooter and walking even more. I may have to revisit the scooter yet again. And why is the question hypothetical? It's down a long and steep hill from my house to the store and, more importantly, up that long and steep hill to get back.
To recap:
Electric Scooter: 2.83*10^6 joules
Bicycle: 5.76*10^6 joules
Walking: 17.5*10^6 joules
smart fortwo: 28.9*10^6 joules
Land Rover LR3 HSE: 54.2*10^6 joules
Update: A very interesting analysis of the bicycle versus electric bicycle (scooter) energy requirements that includes life-cycle energy consideration done as a term paper is available here.
Sunday, August 23, 2009
The CNW Research - Pacific Institute - Slate Magazine kerfuffle
Let me start by saying I've wanted for a long time to use "kerfuffle" in a blog post. The contretemps that's the subject of this post fits the word perfectly. You may remember a few years back that a meme went around stating that the "lifetime energy usage" of a Hummer was less than that of a Prius. As the rumblings had it, this was primarily because of the energy required to manufacture, carry, and dispose of the Prius' battery pack.
The origin of this meme was a report by an entity called CNW Research that is, as best I can tell, a marketing research firm. The report claims to use 3,000 data points to put a price tag on the "dust to dust" (inception of design to manufacture to use to disposal and recycling of the vehicle at its "end of life") energy of a wide variety of vehicles. It's stated that they even include the fuel used driving to work by the employees of the vehicle's manufacturer in their calculations.
They rank many vehicles in a tremendous variety of categories but the phrase that caught on was that the Prius uses more energy from dust to dust than a Hummer.This is despite the fact that the report itself puts these two vehicles in separate categories. CNW Research recommends that the report be used to compare vehicles within a category, not across categories.
On its face, this result seems ludicrous. And Pacific Institute (here) and Slate Magazine (here), among others have strongly criticized the results. CNW Research has defended their results at pages linked here.
Instinct often leads one astray in the field of energy, let's take a brief look. The actual report is available at CNW Research's site in pdf and Excel versions. The pdf is 458 pages and 3 MB so it's a chore.
That said, there are some telling indications to start with, among which are the misuse of units (watts, kilowatt hours, joules, etc.). In fact, they refer to "juelles." Not confidence-inspiring, to say the least. There are strange estimates of vehicle lifetime years of use (e.g., for the H1 34.96 years) with no indication of the source of the number. These numbers are critical because the ultimate number they give is energy cost per mile. The denominator, miles, is found by taking lifetime in years and multiplying by miles per year. There's no indication of the source of either number (other than "CNW Research").
It appears that they use several resales to secondary owners in their cost calculations, though this clearly has nothing whatsoever to do with energy expenditure - I doubt that the writing of a check, and a trip to DMV are significant energy expenditures in the final analysis. And cost is a telling indication. For example, the Prius is stated to have a "life-cycle energy cost" of $3.25/mile. Using the lifetime mileage of 109,000 miles, that means that, exclusive of the materials cost of the Prius, profit for the manufacturer and the various suppliers, distributors, etc., the energy from cradle to grave of a Prius costs over $350,000.
Now, suppose I buy a loaded Prius for $25,000 and drive it 109,000 miles. Using the IRS rate, a decent proxy for all costs of driving (including depreciation, maintence, etc.) and excessive if anything for the Prius, the total cost (not adjusted for time value of money) would be $84,950. Even assuming 100% of that is energy costs, who's paying the other $269,300?
I will acknowledge that "society" pays a significant amount in the form of road maintenance and other public goods. And CNW Research claims to account for these. But it's impossible that this would account for the enormous discrepancy.
All that said, it's clear that CNW Research has invested a lot of time and effort and gathered a spectacular amount of data. I'd like them to be open with it because the conclusions they've reached, correct or incorrect, are quite important. I don't accuse them of bias on the basis of funding, I don't see that kind of skew in their analysis and they claim to have funded it internally. Fair enough, I'll take them at their word.
If this information were to presented as a peer-reviewed publication and the data made available, it would be extremely valuable. I understand that CNW Research wants to profit from their efforts and I'm sympathetic to the profit motive. But the results, as presented, leave ample room for skepticism at best and dismissal at worst. To their credit, they have extensive appendices and answer many questions emailed by readers. Unfortunately, they don't clear up the points listed above.
The origin of this meme was a report by an entity called CNW Research that is, as best I can tell, a marketing research firm. The report claims to use 3,000 data points to put a price tag on the "dust to dust" (inception of design to manufacture to use to disposal and recycling of the vehicle at its "end of life") energy of a wide variety of vehicles. It's stated that they even include the fuel used driving to work by the employees of the vehicle's manufacturer in their calculations.
They rank many vehicles in a tremendous variety of categories but the phrase that caught on was that the Prius uses more energy from dust to dust than a Hummer.This is despite the fact that the report itself puts these two vehicles in separate categories. CNW Research recommends that the report be used to compare vehicles within a category, not across categories.
On its face, this result seems ludicrous. And Pacific Institute (here) and Slate Magazine (here), among others have strongly criticized the results. CNW Research has defended their results at pages linked here.
Instinct often leads one astray in the field of energy, let's take a brief look. The actual report is available at CNW Research's site in pdf and Excel versions. The pdf is 458 pages and 3 MB so it's a chore.
That said, there are some telling indications to start with, among which are the misuse of units (watts, kilowatt hours, joules, etc.). In fact, they refer to "juelles." Not confidence-inspiring, to say the least. There are strange estimates of vehicle lifetime years of use (e.g., for the H1 34.96 years) with no indication of the source of the number. These numbers are critical because the ultimate number they give is energy cost per mile. The denominator, miles, is found by taking lifetime in years and multiplying by miles per year. There's no indication of the source of either number (other than "CNW Research").
It appears that they use several resales to secondary owners in their cost calculations, though this clearly has nothing whatsoever to do with energy expenditure - I doubt that the writing of a check, and a trip to DMV are significant energy expenditures in the final analysis. And cost is a telling indication. For example, the Prius is stated to have a "life-cycle energy cost" of $3.25/mile. Using the lifetime mileage of 109,000 miles, that means that, exclusive of the materials cost of the Prius, profit for the manufacturer and the various suppliers, distributors, etc., the energy from cradle to grave of a Prius costs over $350,000.
Now, suppose I buy a loaded Prius for $25,000 and drive it 109,000 miles. Using the IRS rate, a decent proxy for all costs of driving (including depreciation, maintence, etc.) and excessive if anything for the Prius, the total cost (not adjusted for time value of money) would be $84,950. Even assuming 100% of that is energy costs, who's paying the other $269,300?
I will acknowledge that "society" pays a significant amount in the form of road maintenance and other public goods. And CNW Research claims to account for these. But it's impossible that this would account for the enormous discrepancy.
All that said, it's clear that CNW Research has invested a lot of time and effort and gathered a spectacular amount of data. I'd like them to be open with it because the conclusions they've reached, correct or incorrect, are quite important. I don't accuse them of bias on the basis of funding, I don't see that kind of skew in their analysis and they claim to have funded it internally. Fair enough, I'll take them at their word.
If this information were to presented as a peer-reviewed publication and the data made available, it would be extremely valuable. I understand that CNW Research wants to profit from their efforts and I'm sympathetic to the profit motive. But the results, as presented, leave ample room for skepticism at best and dismissal at worst. To their credit, they have extensive appendices and answer many questions emailed by readers. Unfortunately, they don't clear up the points listed above.
Embarrassed to be conservative
I find myself going "off topic" more frequently on this blog as it becomes an avenue for me to express opinions on sociological and political matters. This may cause some dismay for those who've followed me to understand how it's possible to get 21 m.p.g. in a Land Rover or the effect on U.S. primary energy consumption should everyone switch to hypermiling. Sorry.
As I've intimated from time to time, I'm not a big government liberal. If anything, my political philosophy revolves around small-l libertarianism. That is, personal responsibility for outcomes and minimal government involvement in the day-to-day lives of the populace. I don't tend to support the attitude of "there's something we don't like, let's involve the government in the solution," and thus could be considered "conservative" in a sense. But what is it I'd like to conserve?
I'd like to conserve the natural resources necessary for both the advancement of civilization and the health of the entire ecology. I'd like to conserve our financial resources to enable us to invest in our future. I'd like to conserve our freedom to act in our own best interest so long as it can be done without the use of force, the threat of force, fraud, or coercion. In a nutshell, I believe that's what conservatism should mean.
I don't want to waste time and bytes on the truly wacko birthers and the like, though I'd point out that those who decry that conservatism leads to birther morons must then acknowledge that liberalism leads to truther fools (though I'll concede that there are nut cases of the black helicopter variety in the truther movement as well). In any case, my problem is with what has now become "mainstream" conservatism as represented by James Inhofe, Michelle Malkin, Rush Limbaugh, Glen Beck, Sarah Palin, George Will, etc.
These spokespersons and their ilk have turned the political discourse into a win at all costs war. Among the casualties of this war are civility, honesty, integrity, and reason. The "death panels" are one of the latest examples of the intellectual corruption of the conservative movement. As Mark Hoofnagle states in his Denialism blog post, there is a debate to be had on health care, but the idiotic shrieking and bald faced lies of the so-called conservatives are preventing us from having it.
Similarly, how to proceed to a world of lower energy conversion rates, given the extremely low rates and high populations of the developing world and their reasonable desire to increase those rates, is a complex topic requiring reasoned discussion and rational action. Whether one comes at the energy issue from the point of view of peak oil and resource depletion, climate change, or both, it's clear to any thinking person that we can't have nine billion people converting primary energy to heat at the U.S. rate of 11 kilowatts per capita. This would lead to a complete collapse of civilization, either through self-poisoning or complete resource depletion, or both, economic theory notwithstanding.
Yet the Moranos and the Inhofes continually propagate all manner of distortions implying that business as usual is the answer.
I'm not a big fan of categorizing my political philosophy with a single word, but if those I've mentioned are conservative, I most certainly would be embarrassed for the word to be applied to me.
As I've intimated from time to time, I'm not a big government liberal. If anything, my political philosophy revolves around small-l libertarianism. That is, personal responsibility for outcomes and minimal government involvement in the day-to-day lives of the populace. I don't tend to support the attitude of "there's something we don't like, let's involve the government in the solution," and thus could be considered "conservative" in a sense. But what is it I'd like to conserve?
I'd like to conserve the natural resources necessary for both the advancement of civilization and the health of the entire ecology. I'd like to conserve our financial resources to enable us to invest in our future. I'd like to conserve our freedom to act in our own best interest so long as it can be done without the use of force, the threat of force, fraud, or coercion. In a nutshell, I believe that's what conservatism should mean.
I don't want to waste time and bytes on the truly wacko birthers and the like, though I'd point out that those who decry that conservatism leads to birther morons must then acknowledge that liberalism leads to truther fools (though I'll concede that there are nut cases of the black helicopter variety in the truther movement as well). In any case, my problem is with what has now become "mainstream" conservatism as represented by James Inhofe, Michelle Malkin, Rush Limbaugh, Glen Beck, Sarah Palin, George Will, etc.
These spokespersons and their ilk have turned the political discourse into a win at all costs war. Among the casualties of this war are civility, honesty, integrity, and reason. The "death panels" are one of the latest examples of the intellectual corruption of the conservative movement. As Mark Hoofnagle states in his Denialism blog post, there is a debate to be had on health care, but the idiotic shrieking and bald faced lies of the so-called conservatives are preventing us from having it.
Similarly, how to proceed to a world of lower energy conversion rates, given the extremely low rates and high populations of the developing world and their reasonable desire to increase those rates, is a complex topic requiring reasoned discussion and rational action. Whether one comes at the energy issue from the point of view of peak oil and resource depletion, climate change, or both, it's clear to any thinking person that we can't have nine billion people converting primary energy to heat at the U.S. rate of 11 kilowatts per capita. This would lead to a complete collapse of civilization, either through self-poisoning or complete resource depletion, or both, economic theory notwithstanding.
Yet the Moranos and the Inhofes continually propagate all manner of distortions implying that business as usual is the answer.
I'm not a big fan of categorizing my political philosophy with a single word, but if those I've mentioned are conservative, I most certainly would be embarrassed for the word to be applied to me.
Wednesday, August 12, 2009
The law of dimishing returns, the Chevy Volt, gas mileage, and hot air
The Chevy Volt, expected to hit the market in 2010 is claimed to achieve 230 m.p.g. in city driving. Is this possible? If so, how significant is it? Over at one of my favorite haunts, Ecomodder.com, Benjamin posted a blog entry about the Volt and the claims for it.As is my nature, I was compelled to dig into the numbers. I commented there that it sounds suspicious. The claims for the Volt are that it will achieve "up to 40 miles" on electricity only and that it will achieve an efficiency on electricity only of 25 kilowatt hours per 100 miles on the EPA city cycle. This is stated to cost between $0.75 and $2.50 depending on electric rates. Interesting.
This is saying that, when using only electricity, the vehicle will have an energy cost of $.0075 and $.025 per mile. That is, between three quarters of a cent and 2 and a half cents per mile. Now, I'm currently getting 21 m.p.g. and spending about $0.15, i.e., fifteen cents per mile on energy. Comparing to the low end of the electrical cost, I'm spending 20 times as much on energy. At the high end, it's six times as much. So multiplying 21 m.p.g. by 6 and by 20, you'd infer that the Volt is achieving something from 126 m.p.g. to 420 m.p.g. just on a cost of energy basis. 230 m.p.g. is in this range, but this isn't very enlightening. Let's try something else.
We'll work with the 25 kilowatt hours (25 kWH) per 100 miles. A kilowatt hour of electricity is 3.6 megajoules, so 25 kWH is 90 megajoules. Since a gallon of gasoline will release about 125 megajoules of thermal energy upon oxidation, we can say that the Volt will go 100 miles on the energy contained in (90/125) or 0.72 gallons of gasoline, thus getting roughly the equivalent of 100/0.72 or about 139 m.p.g. (or, as Doug Pelmear would say, 139 MPGe).
So where did 230 m.p.g. come from? I'm not sure. One possibility is that they look at, say, a 50 mile trip, figure 40 miles on the electric motor and don't count that energy expenditure, then travel the remaining 10 miles on a gasoline engine that gets 46 m.p.g. while powering a generator to propel the car and recharge the battery. Conveniently, that would indicate travelling 50 miles on 10/46=0.217 gallons, or 230 m.p.g. At this point, I don't know.
In any case, suppose that we do have such a vehicle. What would it mean? In an earlier post I went into some detail on the fact that, the worse the gas mileage being achieved, that is, the lower the m.p.g. the more fuel is saved by relatively small improvements in that number. This result is surprising to some because miles per gallon is really not the best way to directly look at efficiency. The better way is gallons per mile, the inverse.* The Volt will illustrate the other end of the spectrum from that described in my previous post.
Let's say I trade a Toyota Yaris, where I was getting 30 m.p.g. driving mostly in the city for a Chevy Volt where I now get "the equivalent of" 230 m.p.g. Suppose I drive 10,000 miles per year. I'll go from burning 333 gallons of fuel to the equivalent of 43.5 gallons, saving 290 gallons.
Meanwhile, my Doppelgänger is driving his LR3 HSE, mostly in the city, and getting 15 m.p.g. He uses 667 gallons to drive 10,000 miles. He trades it in on a MINI Cooper and gets 30 m.p.g., using 333 gallons in the course of his 10,000 miles of driving. He saves 333 gallons, 43 more than I did by going from 30 m.p.g. to 230 m.p.g. This is the law of diminishing returns in action.
From a person who coasts to the cross street from his driveway before turning on the car to save a milliliter or two of fuel, it might seem odd to read something apparently dismissive of such extraordinarily good fuel economy. But I'm not dismissing it, only attempting to put it into perspective as to what's being achieved and where the big savings lie. In fact, my hat's off to Chevy for bringing this ultra-efficient vehicle to market but they need to be clear with their claims.
* In the Great White North, where civilized people use the SI ("metric") system, fuel economy is rated in liters per 100 kilometers (though "liter" isn't strictly a SI unit). My 21 m.p.g. rating turns to 11.2 liters per 100 kilometers. The Volt's stated 230 m.p.g. would be 1.02 liters per 100 kilometers.
Update: Rhett, over at DOT PHYSICS, has made a very thorough analysis of the Volt. Take a look!
Update 2: A better debunking than mine of the Chevy Volt m.p.g. claim is at Good Math, Bad Math. I've added this great blog to my blog roll. You're welcome.
By the way, I found Good Math, Bad Math by typing the conversion from 230 m.p.g. into the Google calculator. It made the conversion AND came up with the blog site. You have to love the Google folks. Even if you equate them to the Borg.
Update 3: Apparently, from reading the comments to the Good Math, Bad Math post linked above, Chevy is "just following orders," i.e., they're going by the tentative rules promulgated by the EPA for the fuel economy ratings of plug-in hybrids. I still think Chevy should be clear. As Rhett shows on his Dot Physics site (also linked above) if you pull out of your driveway and drive 230 miles, you'll use way more than a gallon of gas.
Saturday, August 08, 2009
Time out
I am by nature a cynical and pessimistic person (not the same thing - it's said that an optimist is a father who will loan his teenager the car, a pessimist is one who won't, and a cynic is one who did). I don't say this to brag, I actually try to at least act as if I'm not. This blog covers topics that will, if major changes aren't forthcoming (and there's no reason to believe they will be), result in unprecedented trauma in our so-called social contract. Now, maybe we'll adapt and the result will be a stable and sustainable societal arrangement, albeit at a lower level of energy conversion. Maybe it will be a Mad Max world. I'd like to hope the former, but my makeup makes me dubious.
Thus, it's significant to me when I find something that makes me feel that it's not all bad. A few months ago, I was watching a youtube video of Leo Kottke, a guitarist I've admired for years and seen on multiple occasions. Youtube suggested I might want to see videos featuring Tommy Emmanuel, of whom I'd never heard. I didn't click on them for the first few times they came up next to Leo, but I finally did. Let me say that Tommy's talent, skill, and love of music have become one of the things that makes me believe there's good in the world and things worth preserving.
I drove four and a half hours to see Tommy Emmanuel perform in Exeter, CA and, though I anticipated that it would be a wonderful experience, I tremendously underestimated how moving it would be. His videos are all over youtube and, since this is a non-commercial blog, I've decided to put one here. It's called "Those Who Wait." I apologize in advance for no physics, vehicle, energy, or gasoline content but I feel compelled to share my wonder at this uniquely talented and genuinely beautiful musician and songwriter (the composition featured here is his). Click on it, you'll thank me. If you're wondering if he's capable of something a little more up-tempo, check out his Guitar Boogie. If your jaw doesn't hit the floor, you have more self-control than I.
Thus, it's significant to me when I find something that makes me feel that it's not all bad. A few months ago, I was watching a youtube video of Leo Kottke, a guitarist I've admired for years and seen on multiple occasions. Youtube suggested I might want to see videos featuring Tommy Emmanuel, of whom I'd never heard. I didn't click on them for the first few times they came up next to Leo, but I finally did. Let me say that Tommy's talent, skill, and love of music have become one of the things that makes me believe there's good in the world and things worth preserving.
I drove four and a half hours to see Tommy Emmanuel perform in Exeter, CA and, though I anticipated that it would be a wonderful experience, I tremendously underestimated how moving it would be. His videos are all over youtube and, since this is a non-commercial blog, I've decided to put one here. It's called "Those Who Wait." I apologize in advance for no physics, vehicle, energy, or gasoline content but I feel compelled to share my wonder at this uniquely talented and genuinely beautiful musician and songwriter (the composition featured here is his). Click on it, you'll thank me. If you're wondering if he's capable of something a little more up-tempo, check out his Guitar Boogie. If your jaw doesn't hit the floor, you have more self-control than I.
Sunday, August 02, 2009
Why "Hamiltonian Function"?
Physicists (of which I am most emphatically not one) will instantly recognize the "Hamiltonian." It's not about a horse race (though I stuck "function" on in the name to distinguish it from that) nor does it refer to a Founding Father. Rather, the Hamiltonian is a function that represents the total energy of a system utilizing a reformulation of Newtonian mechanics called, unsurprisingly, Hamiltonian mechanics. Since this blog is nominally about energy, how to minimize its expenditure, and take maximum advantage the energy I convert, the Hamiltonian Function as a title seems appropriate to me.
Though it typically doesn't make a particular problem easier to solve, it's considered that the Hamiltonian of a system is capable of providing deeper insight into the nature of the system under consideration than the second order differential equations of Newtonian mechanics. This is particularly true when the system involves quantum mechanical considerations, though it is completely general in its application. I'd be flattering myself to contend that my little blog is capable of providing deep insights, but I do hope that it can provide a different point of view and be thought provoking.
Though it typically doesn't make a particular problem easier to solve, it's considered that the Hamiltonian of a system is capable of providing deeper insight into the nature of the system under consideration than the second order differential equations of Newtonian mechanics. This is particularly true when the system involves quantum mechanical considerations, though it is completely general in its application. I'd be flattering myself to contend that my little blog is capable of providing deep insights, but I do hope that it can provide a different point of view and be thought provoking.
Playing with an iPhone
I dumped my forever locking up Samsung Omnia for an iPhone 3Gs. As most will know, one of the major selling points of the iPhone (and a good one at that, though some stridently disagree) is the availability of an ever-growing "app store." I've installed six apps so far, but this post is about the Wavefront Labs Accelerator Data Pro and Cross-Discipline Technology, LLC Gforce apps. These apps take the data from the three axis accelerometer in the iPhone and display it or log it. I thought it would be interesting to document exactly how slowly I accelerate, though I already had a pretty good idea from logging speed vs. time in five second intervals as mentioned in this post.
I've used the Gforce app more frequently because, well, I'm driving and the display is much more intuitive to understand at a glance (click on the photo for an enlarged view). It's capable of holding the peak in longitudinal and transverse axes for a user-set amount of time and of sounding an alarm when user-set limits are exceeded in either axis. The Acceleration Data Pro is capable of saving data to a file and exporting for subsequent analysis. I intend to so use it but have not done so yet.
As readers of this blog might imagine, my positive acceleration numbers are quite small, rarely exceeding 0.1 g (0.98 meters/sec^2), though the first movement from a stop is typically about 0.15 g. I estimate that the average acceleration up to speed is about 0.055 g. To get a feel for this, that means I'm gaining about 1.2 miles/hour in speed with each second. Using that acceleration, I get to 55 miles/hour in about 45.6 seconds. This is somewhat faster than the results I got from timing, referred to above. I don't know if I'm getting more rambunctious in my application of throttle (doubtful, judging from the reactions of those with whom I share the road) or I'm "guesstimating" the average acceleration from the iPhone inaccurately.
Probably of more interest, there's a curved ramp from the 605 freeway northbound to the 91 freeway eastbound that I take at a speed, v, of about 50 miles/hour (22.35 meters/second). The Gforce shows a centripetal acceleration, a, of about 0.38 g, or 3.724 meters/second^2. Now, since a=v^2/r, where r is the radius of the path described by my vehicle (for a very nice lesson on this topic, see Rhett Alain's Dot Physics entry), I can estimate that the radius of the ramp is about 134 meters. How can you not love the ability of the iPhone to measure the radius of curvature of a freeway on-ramp?
The ramp has a recommended maximum speed of 35 miles/hour (I maintain 50 m.p.h. because I don't want to apply brakes). Working backwards, this means that CalTrans has designed the ramp for a recommended centripetal acceleration of about 0.19 g. They should put that on the sign!
Starting early in my first high school physics class and reemphasized ever since, when looking at any physical situation, when in doubt, F=m*a. That is, force equals mass times acceleration, Newton's second law (well, sort of - Newton actually framed it as net force equals rate of change of momentum but it's the same thing). Let's apply it here. The mass of my Land Rover LR3 HSE is about 2,676 kilograms, and I take that curve at about 0.38 g or 3.72 meters/second^2. This means F is about 9966 Newtons, or about 2,240 pounds. Note that this is over 10 times the force required to move the LR3 down the road at 55 m.p.h. and it's applied by the road to the vehicle through the tires. No wonder they wear out!
Update: To really see what can be done with the iPhone and its acclerometer and GPS, see Michael Koppelman's exploits with an iPhone in a model rocket.
Update 2: I haven't done any programming since about 1989, and that was meager. My last (semi) serious bout with programming was in 1980. I wonder how hard it would be to write and install a program for the iPhone that would provide average acceleration in each axis from a start to a stop time, or average over user set intervals, say, every second?
I've used the Gforce app more frequently because, well, I'm driving and the display is much more intuitive to understand at a glance (click on the photo for an enlarged view). It's capable of holding the peak in longitudinal and transverse axes for a user-set amount of time and of sounding an alarm when user-set limits are exceeded in either axis. The Acceleration Data Pro is capable of saving data to a file and exporting for subsequent analysis. I intend to so use it but have not done so yet.As readers of this blog might imagine, my positive acceleration numbers are quite small, rarely exceeding 0.1 g (0.98 meters/sec^2), though the first movement from a stop is typically about 0.15 g. I estimate that the average acceleration up to speed is about 0.055 g. To get a feel for this, that means I'm gaining about 1.2 miles/hour in speed with each second. Using that acceleration, I get to 55 miles/hour in about 45.6 seconds. This is somewhat faster than the results I got from timing, referred to above. I don't know if I'm getting more rambunctious in my application of throttle (doubtful, judging from the reactions of those with whom I share the road) or I'm "guesstimating" the average acceleration from the iPhone inaccurately.
Probably of more interest, there's a curved ramp from the 605 freeway northbound to the 91 freeway eastbound that I take at a speed, v, of about 50 miles/hour (22.35 meters/second). The Gforce shows a centripetal acceleration, a, of about 0.38 g, or 3.724 meters/second^2. Now, since a=v^2/r, where r is the radius of the path described by my vehicle (for a very nice lesson on this topic, see Rhett Alain's Dot Physics entry), I can estimate that the radius of the ramp is about 134 meters. How can you not love the ability of the iPhone to measure the radius of curvature of a freeway on-ramp?
The ramp has a recommended maximum speed of 35 miles/hour (I maintain 50 m.p.h. because I don't want to apply brakes). Working backwards, this means that CalTrans has designed the ramp for a recommended centripetal acceleration of about 0.19 g. They should put that on the sign!
Starting early in my first high school physics class and reemphasized ever since, when looking at any physical situation, when in doubt, F=m*a. That is, force equals mass times acceleration, Newton's second law (well, sort of - Newton actually framed it as net force equals rate of change of momentum but it's the same thing). Let's apply it here. The mass of my Land Rover LR3 HSE is about 2,676 kilograms, and I take that curve at about 0.38 g or 3.72 meters/second^2. This means F is about 9966 Newtons, or about 2,240 pounds. Note that this is over 10 times the force required to move the LR3 down the road at 55 m.p.h. and it's applied by the road to the vehicle through the tires. No wonder they wear out!
Update: To really see what can be done with the iPhone and its acclerometer and GPS, see Michael Koppelman's exploits with an iPhone in a model rocket.
Update 2: I haven't done any programming since about 1989, and that was meager. My last (semi) serious bout with programming was in 1980. I wonder how hard it would be to write and install a program for the iPhone that would provide average acceleration in each axis from a start to a stop time, or average over user set intervals, say, every second?
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