“Be kind, for everyone you meet is fighting a hard battle” - Often attributed to Plato but likely from Ian McLaren (pseudonym of Reverend John Watson)

Thursday, July 17, 2014

Why Dropbox?

I subscribe to "Quora," which is a place where people ask questions and people who believe that they have some subject matter expertise in the area of the question will provide answers. Naturally, you can select areas of interest and new questions and answers in those areas come to your email inbox on a regular basis with links to the full set of such questions and answers. I'm a big fan.

I'm also a big user of Dropbox, a "cloud" storage site that syncs with all of my devices (and I have devices operating on Android, iOS, macOS, and Windows - nothing Linux yet), and those two sites intersected with someone asking "Why is Dropbox more popular than other programs with similar functionality?" I found the following answer from Michael Wolfe to be both dead-on accurate and hilarious:

Well, let's take a step back and think about the sync problem and what the ideal solution for it would do:

  • There would be a folder.
  • You'd put your stuff in it.
  • It would sync.

They built that.

Why didn't anyone else build that? I have no idea.

"But," you may ask, "so much more you could do! What about task management, calendaring, customized dashboards, virtual white boarding. More than just folders and files!"

No, shut up. People don't use that crap. They just want a folder. A folder that syncs.

"But," you may say, "this is valuable data... certainly users will feel more comfortable tying their data to Windows Live, Apple's MobileMe, or a name they already know."

No, shut up. Not a single person on Earth wakes up in the morning worried about deriving more value from their Windows Live login. People already trust folders. And Dropbox looks just like a folder. One that syncs.

"But," you may say, "folders are so 1995. Why not leverage the full power of the web? With HTML5 you can drag and drop files, you can build intergalactic dashboards of statistics showing how much storage you are using, you can publish your files as RSS feeds and tweets, and you can add your company logo!"

No, shut up. Most of the world doesn't sit in front of their browser all day. If they do, it is Internet Explorer 6 at work that they are not allowed to upgrade.  Browsers suck for these kinds of things. Their stuff is already in folders. They just want a folder. That syncs.

That is what it does.

Sunday, July 13, 2014

"Solar Freakin' Roadways!"

Artist's rendition, courtesy Solar Roadways
A commenter brought up the "Solar Roads" concept with this link. I'd seen it mentioned in the past but had never really dived in to analyze it. In looking around, there are a fair number of youtube videos claiming to debunk the concept, as well as an exuberant video singing the praises of the idea (the one from which the title of this post came). And Julie and Scott Brusaw, the inventors of the concept, have both SBIR grants and a successful Indiegogo campaign. And they mount a defense against the so-called "debunkers" here.

So what is the Solar Roadways concept? The idea is to replace typical pavement materials (asphalt, concrete) with hexagonal tiles that contain solar photovoltaic cells along with circuitry and LEDs. The cells and circuitry are covered with a textured clear glass to provide traction for vehicles and protection for the electronics. Among other things, the solar roadway would harvest solar energy to provide distributed power, heat the tiles to melt snow and ice (though this would be done, as I understand it, with grid power since the energy demands to melt solid water exceed what the solar panels could provide), light the LEDs for lane markings, messages, etc., be sensitive to load and thereby be able to signal through the LEDs that there is a pedestrian or animal in the roadway, and a variety of other ideas.

So, does such a concept have any credibility? To start, Scott Brusaw has significant engineering background and doesn't appear to be either an idiot or a charlatan. The Brusaws recognize that the tiles won't provide electricity at night and thus, like a typical home solar installation, utilize the grid as a "storage medium," that is, they are a source of electrical input to the grid when the sun shines to the extent that their production exceeds their own demand (energizing LEDs, etc.), and utilize electricity from the grid to accomplish their purposes when it does not.

But let's think a bit. At the Renewable Energy Resource Center (a project of the National Renewable Energy Laboratory, RREDC & NREL respectively) there's a very nice page where we can estimate solar irradiance. The page allows us to choose dates, configurations, etc. Using average irradiance, March, horizontal flat plate (to represent a road), I get the map at left. It represents average everything (March at the equinox, average irradiation, etc.).

Let's take an average location, say, Kansas. It looks to me like about 4.5 kWh/m^2/day (kilowatt hours per square meter per day) would be a good number to use. Now, the Brusaws calculate using 18% efficiency in their cells. I'll charitably assume that the textured glass lets 100% of the incoming sunlight through to the underlying photovoltaic cells. Thus, the cells can capture 0.18*4.5=0.81 kWh/m^2/day. Where I live, that's worth a bit under a dime.

But suppose that Kansas (or wherever) has a feed-in tariff for renewable energy. Feed-in tariff rates are quite variable even by state, but let's generously use $0.30/kWh. That makes the electricity produced by a square meter of photovoltaic cells in the Solar Roadway worth a bit under a quarter, but let's call it $0.25. Of course, the DC produced by the cells must be converted to AC to feed the grid. An advanced "micro inverter" to accomplish this task is about 96% efficient, so that the 0.81 kWh is reduced to 0.78 kWh, worth about $0.23. In a year, the square meter would generate about $85.

The Brusaws claim that a tile is designed with a lifetime of 20 years. I doubt this, but let that pass. This would mean that the square meter of tile would produce, in its lifetime, $1,700 worth of electricity. Yes, rates may rise, but I didn't discount the cash flow to represent the time value of money. Further, it's unlikely that feed-in tariffs will endure as solar becomes more widely adopted, and feed-in tariffs aren't universally adopted in any case. Thus, I'm claiming a wash there.

Now, the assumptions here are, without a doubt, generous. No adjustment was made for transmission of the glass wearing layer, for any accumulation of road grime, blown in dust and dirt, portion of pavement shaded by vehicles, etc. But I will adjust for the fact that the LEDs, electronics, etc. take a significant portion of the area of each tile presented to the sun. While no figures are given in Solar Roadway's site, estimating from the various photos, I think that no more than 75% of the area of a Solar Roadway pavement would generate electricity. This reduces that $1,700 per square meter of paving to $1,275 and the annual revenue to a bit under $64. It reduces the electrical input to the grid to 0.585 kWh per day per square meter.

Now, the power required to have the LEDs visible in bright daylight at, say, 17 meters might be on the order of 300 watts/square meter of lighted area. This may seem like a lot, but consider that only a very small portion of any paved area is lit (see the graphic at the top of the post). If we conservatively assume that the worst case is that 5% of paved area may be lit, that would constitute 15 watts. And this is for daylight, the LEDs could (and, no doubt would) be dimmed at night. I'm going to estimate that this would require 240 watt hours/day or 0.24 kWh per day per square meter. Note that this is (.24/.78) = 0.308 or about 31% of the generating capacity of a square meter of tiles. This reduces the $1,275 to about $880 and the $64 to about $44. It reduces the electrical energy fed to the grid each day to 0.40 kWh per day per square meter.

I have not been able to find a cost estimate for a tile on the Solar Roadways web site, but if I use what I can find for tempered glass, photovoltaic panels, and electronics, I can (very roughly) estimate that square meter of these tiles might cost around $250 at wholesale prices. This doesn't include installation. I would estimate that a square meter of installation might take another $100 per square meter for a total of $350. Thus, an installation might pay for itself in eight years or so. That's not really so bad. And note that we don't ask concrete or asphalt pavements to generate any income at all (tolls don't count - the same could be done for a Solar Roadway). Note that this doesn't count the associated infrastructure for cable runs, etc. Add another $150. Since much of the pertinent information with respect to composition, dimensions, etc. isn't given, this is the best that I can do.

The Brusaws go on to claim that replacing the entire paved area of the US with Solar Roadway tiles could generate three times the electricity usage of the Country. Of course, this ignores the intermittency issue which, for a local installation, can use the "grid storage" mentioned above but which is out of the question when trying to replace the entire electrical generating capacity of the Country.

But let's carry on undaunted. I can use numbers from this Wikipedia page to estimate that approximately 74 billion square meters of land in the US is paved. Taking this number times the approximately (on average assumptions for everything) 0.4 kWh/day times 365 days per year, we can estimate that replacing all paving with Solar Roadways might generate a bit over 1.09*10^13 kilowatt hours of electricity. Let's just go with 10 trillion kilowatt hours. Here we find that in 2012, US electricity demand was 3,826 billion kilowatt hours, or 3.8 trillion kilowatt hours. Thus, the Brusaws' contention is in the right ballpark (given the proviso above).

What about the Brusaws' contention that the a Solar Roadway could contribute to the charging of an electric vehicle by induction? Let's assume that the car is traveling at the optimal time of day in cloudless skies. The Roadway can deliver something like 180 watts/meter^2 (18% efficiency * 1000 watts/m^2). The vehicle might be 1.75 meters wide and, at 55 m.p.h., spend about 0.04 seconds to traverse a meter. The Solar Roadway can deliver 1.75*1*180 = 315 watts from this area. In 0.04 seconds, it can deliver 0.0035 watt hours of energy. Suppose that an EV needs 10 horsepower to maintain a speed of 55 m.p.h. This is about 7500 watts. It will spend that same 0.04 seconds on a meter and thus need about .083 watt hours of energy. The Solar Roadway can thus (neglecting all other losses) supply about 4% of the energy requirement of this very efficient car. Of course, only a fraction of the roadway would be drawing power, let's say 15%. Thus, maybe 25% of the energy of the vehicular traffic could be supplied if all EVs were that efficient and every vehicle was an EV. Of course, not every vehicle is not an EV and thus this may actually be a significant contributor. Again, a whole lot of estimates went into this and many numbers were quite optimistic.

Finally, what would be the cost? This is even a harder number to estimate. The Brusaws contend that the tiles could, in many cases, be mounted on existing pavements. I seriously doubt that, overlaying pavement is a very difficult civil engineering problem. Profiles must be maintained, gradients must be within specifications, etc. Nonetheless, let's just take $500*74 billion, for a total of $37 trillion. Keep in mind, however, that these existing pavements will ultimately need to be repaired and replaced as they wear out. And a ballpark figure for construction of a new asphalt or concrete pavement is on the order of $150 per square meter.

Admittedly, much of the above is based on estimates that may or may not closely match the real world. Nevertheless, I see nothing that makes me think that the concept is preposterous. I believe that the most important data to acquire is the performance of the tiles under continuous wheel loading over long durations in varying temperature, moisture, and mounting/subsurface conditions.

And one additional major consideration, completely unaddressed by the Brusaws, is the need for paved surfaces to not simply shed all rainfall to storm water management systems for discharge to a lake, river, or ocean. In this regard, materials scientists are hard at work on pervious concrete and pervious asphalt paving systems that drain water to the subsurface layer for absorption into the underlying earth. There's no possibility of this with the Solar Roadway system, and thus an eco-friendly storm water handling system must be made a part of any such design.

Update: A tweet mentioned that the Brusaws had, in fact addressed drainage. A Google advanced search took me to this page. I haven't had time yet to evaluate the plausibility of their scheme, but I was incorrect in the paragraph above to state that the issue was "completely unadressed." My apologies to the Brusaws.

Saturday, July 12, 2014

Feigning literacy, nothin' up my sleeve

Image courtesy of Chris Butler, Big Chris Gallery
I look at various climate related sites, both those who are skeptical of what I'll call climate disruption caused by the products of mankind's burning of fossil fuels and those who accept the theory (using "theory" here as a scientist would use it, analogous to, say, Newton's theory of gravitation). One of the most frustrating things I find is writers who present a veneer of scientific literacy but, upon even cursory investigation by anyone with a reasonable yet far short of specialist knowledge (e.g., myself) are easily revealed to be nonsense. Yet the scientific veneer ("look! charts! equals signs!") can lead people with almost no scientific or mathematical literacy to place credence in this nonsense. And, sadly, that latter group is a very large one.

A good example is to be found here. Those who follow the ebb and flow of the so-called debate around climate disruption will likely have heard of the "hiatus" in warming, that is, a slowing down of the rate of increase of global temperature. Given the demonstrable increase in energy retained by the earth/ocean/atmosphere system (for what is, in my opinion, a silly if not counterproductive "measurement" of this heat, see here) because of our greenhouse gas emissions, scientists have advanced theories for the so-called "missing heat." As best I can determine, the leading theory is that the oceans are heating and doing so to greater depth than had been anticipated.

But Anthony Cox is having none of it. He reproduces the graphic graphic at left. It charts a time series of "Change in Total Heat Content" data from 1955 through (apparently) 2014. As an aside, my pedantry requires that I mention that "heat content," though widely used and accepted, is poor terminology. Heat is an interaction between a system and its surroundings resulting in a change in internal energy of the system. Temperature, in turn, can be (loosely) considered to be a measure of one specific component of average internal energy.

In any case, Mr. Cox objects, and provides charts showing a calculated equivalent temperature rise in degrees celsius. I'm not sure why he bothered to calculate. The source of such data, NOAA's National Oceanographic Data Center, provides a chart with degrees celsius as the ordinate in the same set of charts as that from which the "heat content" chard is reproduced. Such a chart is here and, in fact, the charts showing heat content are computed from temperature measurements.

But what's the difference? Why does one chart show the data in joules and the other in degrees celsius? The joule is a unit of energy. One joule is an extremely small amount of energy in comparison to everyday experience; the heat energy available in a single piece of plain M&M candy is more than 14,000 joules. A gallon of gasoline releases about 125,000,000 joules when completely oxidized. That's why the heat content chart has such huge numbers. What you see on the vertical axis is measured (actually, computed from temperature measurements in the ocean vertical profile) heat content with a reference number subtracted. Accordingly, this is an "anomaly," and each "tick" on the vertical axis represents a 1022 (1 followed by 22 zeros) joules from the reference period. It does not represent the "total heat content" of the oceans. It represents gains and losses in comparison to the reference period.

To the left is the data showing temperature (again, as an anomaly) over the period. Note that this was taken straight from the the NODC web site, no need for the calculations performed by Lucia at the "The Blackboard."

Mr. Cox contends that the heat content anomaly in joules is used because the big numbers look more scary then the same data presented as temperature anomaly in degrees celsius.

This is simply untrue. The amount of energy that will heat a cubic meter of water by 1 degree celsius will heat about 3,100 cubic meters of air (at sea level pressure) by that same degree celsius. This is due in small part to the higher specific heat of water but mostly to water being about 1,000 times as dense as air (again, at sea level pressure). Looked at another way, the amount of energy required to heat the upper 700 meters of ocean worldwide by 1 degree celsius would heat the ENTIRE atmosphere some 170 degrees celsius (assuming that the specific heat of air is constant as temperature changes, which it is not).

Now, is the interaction between incoming solar energy, outgoing long wave radiation, ocean circulation, heat transfer, etc. as simple as this calculation? Of course not. That's why scientists study these things, measure the relevant parameters, seek hypotheses that explain the measurements, etc. Are there significant questions to be answered with respect to the data presented and how it's measured? Yes. Are scientists trying to answer these questions? Yes. That's what science is.

But the conclusion is that energy (referred to by NOAA as "Heat Content" and tracked as an anomaly) is an entirely appropriate way to picture one component of the effect of greenhouse gases on our ocean/atmosphere system. It is NOT a nefarious way to be able to insert scary large numbers into a chart. And, to reemphasize for yet the third time, the same set of NOAA charts that shows the energy anomaly in joules shows its effect in degrees celsius as well. So who really has deception as their goal?

Sunday, July 06, 2014

Jumping the shark*

In other posts, I've made myself clear on what I think is true (I don't say "believe" because I don't want to provide grist for those who say "climate alarmists are more akin to religious zealots than scientists") regarding climate change. And I certainly see vast evidence of propagandizing employed by those who either truly don't believe  think that our carbon dioxide emissions are harmful, or those who profess such beliefs conclusions for other reasons.

On the other hand, now and again I run into something from those who agree in large part with my conclusions regarding disruption of the climate via the products of our burning of fossil fuels that makes me slap my forehead in dismay. An example of this is a paragraph extracted from New South Wales' (Australia) "Road Users' Handbook." On page 39 of that publication, I find the following:


"It is anticipated that current weather patterns will progressively change and  become more unpredictable as a result of climate change. Climate change is the impact on the planet due to greenhouse gas emissions which will increase global temperatures. Climate change is expected to cause unpredictable weather events and conditions such as extreme heatwaves (sic), storms, flooding and bushfires (sic). Driving during extreme weather events or conditions should be undertaken with care and caution..."

It's certainly the case that climate models and fundamental geophysical considerations indicate that severe weather events will increase in various locations because of the displacement from equilibrium in the Earth/atmosphere/ocean energy system due to our emissions of greenhouse gases.

Many, though, will regard this language as a subterfuge to insert a political agenda into a government publication that has nothing to do with the science (and political discourse) of global warming. And, to the driver encountering such conditions, what in the world does it matter to him or her what caused them? It's most emphatically not the case that extreme heatwaves, storms, flooding, and bushfires are new phenomena, only noted in the anthropocene.

Along with inane, counterproductive pieces such as "No Pressure," these sorts of needless, over the top insertions of very real concerns about climate disruption into unrelated publications add nothing and provide ammunition for those who want to point fingers and say "See? It's all a plot on the part of the one-world government manipulators to surreptitiously lead the sheeple to the slaughter." Just say no!

And finally, no such post would be complete without TEOTWAWKI:

*See, for example, this Wikipedia article  or this Urban Dictionary entry for definitions of "jumping the shark."

Saturday, July 05, 2014

It's all in the presentation

Graphic courtesy of NOAA
In the process of trying to understand the trajectory of our climate from a layperson's point of view, albeit one with at least a moderate level of sophistication with respect to basic physics and mathematics, I run across an awful lot of blogs. Some are hosted by actual climatologists, some are hosted by deeply interested people with extensive scientific knowledge but who are not climatologists, some are hosted by interested (and talented) amateurs. These bloggers are firmly convinced that mankind's emissions of carbon dioxide and other greenhouse gases present an imminent danger to our way of life.

There is an alternate universe of blogs from those who are either actually skeptical of any effects we may have on climate or who, for various reasons, write as if they are. Such writers range from those who are openly hostile to those who profess uncertainty. Again, these fall into groups. And again, these writers have vastly differing degrees of scientific sophistication, ranging from those whose career involves the study of climate (though skeptical professional climatologists are few in number) through, again, talented amateurs.

Some of those in the second group, however, are simply hacks. Such a one is the publisher of "Greenie Watch," published by John Ray, Ph.D., out of Brisbane Australia. His latest post discusses the charts one often sees that show global temperature anomalies. These numbers show the deviation from some reference value, typically a long-term average. Such a chart is at the top of this post.

Dr. Ray doesn't like these, and instead shows whole degrees Fahrenheit starting from zero (already questionable, since 0 degrees Fahrenheit has no significance). That results in this:

The point is, of course, that any trend in temperatures looks trivial in comparison to the distance from zero to the measured (calculated?) temperatures.

I thought I'd try something similar. Though I don't know anyone specific, I'd imagine that someone or another has developed a fever in the last 30 days. Let's plot such a person's temperature anomaly:

Woah. This guy had best see a doctor, stat! On the other hand, have a look at this:

I guess he was worried about nothing. And yet these two plots show precisely the same data, one in degrees Fahrenheit above or below 98.6, the other in Kelvins from absolute zero (a zero that, at least, does have some significance).

I may go back and refine these plots, they certainly aren't pretty (I'm working on coming to grips with Matlab and, while some of the manipulation is straightforward, the plotting features frustrate me). But they certainly get across the idea that, in many cases, it's quite straightforward to display data to suit one's agenda. I could almost say, to deceive.