I was looking on Amazon for some videos I wanted when I stumbled across author Alan Weisman. I discovered this eco-evangelist by accident, he was mentioned by several critics of the interesting BBC series "Life After People". Apparently for some real, die-hard anti-man types the BBC series was not sufficiently critical of our "environmental impact", arguing that most traces of man would last less than a century. (Which is why I liked the series, it was remarkably objective and tended to be quite realistic about the limited impact we have had on the world.) Those who did not like the BBC series were full of praise for Weisman's book, which apparently also mentioned pro-cannibalism groups, including a barbecue recipe to accompany human flesh, and promoting the "Human Extinction Movement".

But Weisman is not my topic this time, I am saving his nonsense for later. Instead, I was drawn to the eco-settlement of "Gaviotas" about which Weisman wrote, and which apparently was featured on NPR. This settlement, in an inhospitable part of South America, appears to be some sort of environmentalist cause celebre, with its engineering marvels being covered on two web pages (here and here), and being talked up on a number of green sites.

The problem is, the numbers don't work. Like perpetual motion machines and web pages dedicated to Tesla devices, the technology simply makes no sense.

Let us look at the worst example, the "solar still". As anyone who has ever used solar panels for water heating can attest, it takes a huge number of panels to even heat water to bathing temperature, much less to boil it. Yet the site claims they can boil 8 gallons a day with just one square meter of solar panels. But that just makes no sense.

First, let me point out two issues that do not relate to mathematics. Looking at the diagram there are three problems I can see. First, the water feed doesn't appear to work. I just don't see how the water would get from the reservoir into the heating section, especially as it has to be forced through the pre-heating coils, where it also serves to condense the steam. I suppose the design may be intended to imply the boiling water would turn to steam and go out the valve, creating suction which would draw in water, but with a constant input of heat, the steam could expand quite a bit, and considering the distance the water must travel (including rising through the coils), a lot of energy would be wasted on superheating steam before, eventually, the pressure in the storage tank would force the water into the heating chamber. If there were a pump. I could see it working, but that would defeat the eco-friendly purpose, and is not in the diagram. So, as designed, it appears to me there would be a lot of wasted energy used generating superheated steam before water would be drawn in from the reservoir.

The remaining two non-energy issues are almost as difficult to resolve. First, the storage cylinder appears to be sealed, and without any sort of emergency release valve. Now, I know there is a condenser, but since this operates outdoors, without supervision, it seems designed to be a potential bomb. Either if the cooling water runs out (which is possible as the rest of the page mentions only hand pumps as water sources), or if the ambient temperature or temperature of input water is too high, and the steam does not fully condense, it seems the reservoir for clean water could easily burst the same way boiler used to in steam heated buildings, with the same lethal consequences.

A second issue relates to the water itself. As we read elsewhere, the water comes from subterranean wells, so it is normal groundwater, which means it contains the normal blend of dissolved metals, mineral, salts and so on. So, if this water boils off in the solar panel, those sediments are either concentrated in the remaining water, or, when saturation point is reached (or all the water boils off) is deposited in the solar panel, which would have one of two effects. In the long term it would slowly accumulate, eventually blocking the flow of water through the device. But even in the short term it would be damaging by covering the glass, making the absorption of solar energy less efficient. As this system is promoted as requiring no maintenance and being operable by anyone, that seems a strange oversight.

Then again, not half as strange as the numbers themselves.

If you look at the diagram, the valve into the condenser allows only steam to pass, so the system clearly not only heats, but boils water. So, assuming water comes in at 15 degrees C, how much water could the system boil? Let us start with some assumptions favorable to the system. Most solar systems are lucky to be 30% or 40% efficient, and this seems no exception, even with the attempts to capture waste heat from condensation to pre-heat inbound water. Still, let us assume the system is 100% efficient, despite how unlikely that is, especially given the problem with mineral deposits. Let us be even more generous and assume ti can run 24 hours at the average solar density of the earth (164 W/sq meter). So, given these very favorable, impossible favorable, assumptions, how much water could it boil?

As we said, the average density of solar energy is 164 W/sq m. So a 1 sq m panel would gather 164 Watt-hour per hour. That is equivalent to 590400 joules, or 141048 calories (with a small "c"). It take 1 calorie to raise 1 gram of water 1 degree Celsius. Assuming the water comes in at 15 degrees C (rather high given the depth from which they supposedly pumped water), it would take 85 cal to heat 1 g of water to 100 degrees C. It then takes an additional 539 cal/g to complete the phase shift from liquid to gas. So, each gram of water takes a total of 624 cal. So, in an hour, the system could boil 226 g of water. Or, put another way, it would take between 4 and 5 hours to boil a liter of water. That makes about 1.5 gallons per day, even with these favorable assumptions.

But, according to the description, the system boils 8 gallons a day, even under less than ideal conditions. So, how much energy would that take?

Let us start with absurdly ideal conditions once more. let us assume again 100% efficiency, as well as 24 hour operations at average worldwide solar energy density. In fact, let us give even more advantage, as say the energy density is the equatorial seasonal maximum all year round (274 W/sq m). Finally, let us say the water comes in at 100 degrees C, so that the only energy requirement is the phase transition from liquid to gas.

Even then, a 1 square m solar panel wouldn't do it.

Eight gallons are 30.3 liters. That makes 30300 grams of water. As the energy required to complete the phase transition is 539 calories per gram of water, we would need 16,331,700 calories, or 68,377,562 J. 1 Watt-hour is 3600 J, and so for 24 hours, at 1 Watt we would generate 86,400 J. And so, our imaginary one square meter panel, running at equatorial maximum solar energy density, 24 hours a day, at 100% efficiency, would deliver 23,673,600 J. In other words, even in an imaginary world, where the sun shines 24 hours a day, solar energy transfers with no loss, water comes out of the ground near boiling, and the system is running with unrealistically high solar energy inputs, we STILL need 3 times as many solar panels as described, just to get 8 gallons of water.

Why do I make such a big deal about this? Because it is so obvious. If I can sit down and figure out why the numebrs don't work, why can't NPR? Why are they lauding this eco-paradise, when the systems proposed to power it don't work? If I were to go to NPR with a documentary about a Christian commune powered by secret devices revealed by Jesus that allow believers to fulfill their needs with only 1 hour of work a week, you would bet they would be investigating the numbers. But when it is an eco-utopia? Not a chance. They buy it like an Obama speech, no questions asked.

Nor is the boiler the only dubious plan. look at the "sleeve pump". Two things immediately struck me. First, the talk about the water tension making the drawing difficult seemed pointless, as the water behavior does not change when you pull either the piston or sleeve, so that should be a moot point. The second problem is that, whether  pulling the piston or cylinder, most of the work is not put into moving a piston, but moving the water, and changing which part moves does not change that, so I can't see how they revolutionized the pump by changing the design in this regard. To lift 1 liter of water 1 meter, you have to do enough work to lift 1 kg 1 meter. Yes, there can be additional work if the design is bad, but even with optimal designs, there is no way a child is effortlessly lifting 100 kg of water 100 m, unless the same child could do so with the old pump as well. Then again, from the rather unclear diagrams, I don't know how the "sleeve pump" supposedly works. The diagram on one page looks like it simply would not work, but it is too vague to tell for sure.

And, though I have not run the numbers, I have concerns the oil cooking system has many problems similar to those I mentioned with the solar still. There is simply not enough energy to heat oil sufficiently, not to mention that all food would need to be cooked at once, or else the unused pots would end up wasting energy. On top of that, oil loses heat easily, so it seems the whole system would need heavy insulation to avoid heat loss. And finally, it seems the oil would break down pretty rapidly if not used regularly, which would cause the system to either loses efficiency or even break down. In fact, if they are using a closed cycle, I have to wonder why they chose flammable oil, which undergoes thermal breakdown. It makes sense if they cook IN the oil, but with oil only providing heat, it seems something that both retains heat and does not break down would be better. Though most of those options are pretty "un-green". But I think the oil may actually date from an earlier design where they imagined fryers rather than oil heated pots. Otherwise, the oil is a strange choice.

Then again, I suppose I should not be surprised that this eco-utopia was accepted unquestioningly. As was mentioned in yesterday's Best of the Web, recent evidence shows that I was too generous in my post "The Failure of Peer Review". There I alleged that environmental science was permeated with an unconscious bias, an orthodoxy which colored all decisions. From recently stolen emails, it appears the orthodoxy is not unconscious, but consciously enforced by some who intentionally exclude all conflicting opinion. So, is it any surprise an eco-mouthpiece outfit like NPR would accept at face value dubious claims of environmental commune heaven?

POSTSCRIPT

To see my articles on environmentalism, look at the list of posts following "Bad Economics Part 1".

POSTSCRIPT II

I am not the only individual to question the engineering. The reason I began to look at the numbers was because one of the Amazon comments about a book on Gaviotas mentioned that eh could not figure out how many of the designs worked, and the publisher and author would not provide him with any additional information.

POSTSCRIPT III

As I finished this, I realized why this solar still is such a silly idea. It has no concentrator for solar energy. If diffuse solar energy were powerful enough to boil standing water, then puddles, rivers, even oceans would be boiling off all the time form solar energy. Similarly, if simple solar energy were enough to heat oil tot he temperature needed to cook food, then animals, plants and people would be baking as they walked about. Solar energy is fine for raising the ambient temperature of air, generating some electricity, or warming water, but to boil water or cook food, you need to concentrate it, and these diagrams show no concentration of energy. If they work in reality, then there are many other parts in reality not shown in these diagrams (like huge fresnel lenses).

POSTSCRIPT IV

For those who did not see my comments from last night (when I was unable to edit my blog), here they are:

Still Can't Edit

No luck getting into my blog again. I was going to write about the anti-democratic nature of the EU and tie it into a discussion of the way term limits would change us from a state run by congressmen-for-life into a nation run by EU style bureaucrats, but I can't quite edit yet.

Then again, it is an argument I made before, so maybe it is for the best, as it keeps me from repeating myself.

Having read the two terse blurbs I posted since I could not edit my blog, I have realized they sound rather nice. Maybe I should write my entire blog in the comments. It would force me to be a lot less wordy.

Gah!

Still cannot edit my blog. And it is killing me! I have found books by an eco-hipster promoting what sounds like the green version of perpetual motion, being bought hook line and sinker by NPR and the green groups in general, while also plugging something labeled the "Human Extinction Movement", and all the while being treated like a great sage!

It reads like the worst satire, like the Thoas Pynchon meets Umberto Eco, and yet it is all real! And I can't write about it because TH is down!

Well, bookmarking all the craziest pages, and writing this note, so when TH works again, I will be back plugging away at this one.

I can't wait.

One Example

They discuss some sort of solar water boiler, to sterilize water. The problems are three, as I see it:

1. If you dump boiling water into an enclosed system without a constant outlet or governor, you get a big boom (that was how heating boilers periodically leveled buildings in the past)

2. If the water contained any sediments, the solar tray they use would either clog or get obscured and become much less efficient.

3. The energy is pretty low. Water comes out of the ground, cold. Say 15 deg C at most. Solar energy (avg 164 W per sq meter) give 590400 J/hr or 141048 calories/hr (with a small c). To heat 1 gram of water 85 degrees takes 85 calories. Then to make stream takes another 539 cal, total 624 cal. So, in an hour, if it was 100% efficient, this system could boil 224 g of water, or about one liter every 5 hours, which comes to about a gallon and a half a day. The numbers just don't work.

Yet this "engineering marvel" and others being touted by this eco-utopia (recall, that means "nowhere"), are getting NPR specials and some eco guru is hawking books based on it.

Fine and dandy, except the science doesn't work. Either they drink very little, run hundreds of still,s or are drinking warm water they just imagine was actually boiled and get river blindness and amoebic dysentery at the same rate as everyone else.

(NOTE: The system shows steam collection and a condenser, so I have to assume they say it is boiling. If they just want to heat it to 100 degrees, then the energy needs are less, but then the diagram makes little sense. Or even less sense I should say... Actually, as they talked about hand pumps, the continuous feed system they designed seems inconsistent as well... And there is no way this system, running in a relatively primitive setting is 100% efficient, even with their efforts to trap heat lost in the condenser... Not a chance it gets above 50% at best.)

As you can see, they largely follow the same arguments I made above. But they differed enough I thought it might be worthwhile to include them.