In Search of Skepticism

PHP4B5A1EED0E9E1Why can't our newspaper here in Arizona apply any skepticism to alternate energy technologies?  Sure, I think this technology is cool, where large solar dishes concentrate heat on what appears to be Stirling cycle engines  (the article, true to form, does not explain the technology, but a few hints plus the name of the company "Stirling Energy Systems" seems to point to that answer).  Other concentrator technologies focus on boiling water, so this a new approach to me.

However, why can't the article actually address real issues, like "how does this technology stack up, based on cost and efficiency, vs. other solar technologies."  It says it uses less water than other concentrator technologies, but is it more or less efficient?  No answer.

We can figure a few things out.  First, as with many "renewable" energy technologies, the company selling it engages in nameplate capacity abuse.  A 1MW coal plant produces 1MW all day long.  A 1MW wind plant produces 1MW when the wind is blowing hard, and less at other times.  And a solar plant produces 1MW when the sun is at its peak.   We can address this latter because folks have calculated sun equivalent hours, the number equivalent max sun-hours per day a site gets through the year.  For the best desert sites in the US, this number is around 6.  This means that the actual capacity of this plant is not 1.5MW, as stated in the article, but about a fourth of that, or  0.375MW.

This matters for a couple of reasons.  They state their build cost as $2.8 million per MW, which seems competitive to coal plants which cost $1.0-2.0 per MW, but in fact the reference number for this solar based on an apples to apples capacity comparison is actually  $11.2 million per MW.   The solar plant gets some credit for having no fuel costs, so it might be possible still for its power to be competitive, but it appears form the limited information in the article that it is not:

Singleton would not disclose what SRP will pay for the electricity, but said the utility will pay a premium for the environmental benefits of the power, and that the price is competitive with other sustainable-energy sources such as wind and geothermal power.

In other words, it is not competitive, so much so that they will not even reveal the price, and only subsidies and government mandates make it possible for a power company to buy the power.

Let's do a reality check.  At best, they get 8 dishes per acre, and 25Kw per dish at max sun.  So this is 8 x 25 x 6/24 = 50Kw per acre.   Lets say we want to get rid of coal.  The US generating capacity of coal plants is about 336,000 MW, or 336,000,000 KW.  To replace it with this solar technology would require 6,720,000 acres (10,500 sq miles or 10% of the state of Arizona) and cost $3.76 trillion dollars if located in the best possible solar areas.   This is not cheap but is not awful.

If I am doing the math right, I get something like $70,000 per dish   (1 dish = 25Kw, $2.8 million per MW).  I would think there are a lot of rich folks with some acreage that would pay $70,000 for one of these bad boys.  It would look much cooler than solar panels on the roof.


  1. KTWO:

    Good thoughts.

    The costs of solar and wind have been nearly impossible to pin down. Wind more than solar. People should be wary of factoids, media, press releases from companies, or universities, or government about them.

    We don't believe every advertisement for vitamins. So why believe everything we are told about alternative energy.

    But reliable numbers about costs are emerging. IMO by 2012 they will be solid enough to allow major national decisions about alternative energy.

    On the positive side, solar and wind work. And they can produce a lot of power. There are environmental reasons and political reasons to favor them if the costs can be justified.

  2. Mike C.:

    Certainly looks more reasonable than large reflector fields heating water to steam. I've seen small dishes with small Stirling engines demonstrated and they certainly do work and could be adapted to run almost any sort of generator. Gonna need a damned big battery bank, though - there's that awkward 'night' thing and all.

  3. Sean:

    Is it possible to simple rate these energy sources in kilowatt hours per day, averaged over a year? One advantage you have in Arizona is that your electricty use is likely highest during the hot weather months of the summer and lowest during the cool weather months. Even the time of day for the greatest energy draw probably matches generation. A second point I'd like to make is distribution. How much energy is simply lost to the distribution network? I think this is quite a substantial proportion (>50% ??? .. I really don't know.) But if we assume the distribution losses are high while the demand load and maximum solar generation for power in Arizona are closely matched, how do the cost numbers look when you generate and consume locally?

  4. Ironman:

    They are indeed Stirling engines. The company is already constructing a couple of large installations in California.

    Don't look for rich people to buy one for home use - that would make too much sense. Instead, look for large installations of hundreds of units built with government subsidies - the synchronized motion and scale of such installations is too appealing to the vanity of politicians to let them be used otherwise.

  5. Geoff:

    Your comparison with coal plants is interesting in that you seem to lightly dismiss the cost of fuel.

    Reminds me of the UK hydroelectric schemes a long time ago, they produced by far the most expensive electricity when built (in those days only capital costs were taken into account when building power stations) Now, of cause they produce the cheapest power in the UK.

    Just to think if we had built the Severn Barrage about 8% of UK electric would be green and cheap.

  6. perlhaqr:

    All these "alternate energy" ideas are bullshit. We want less air pollution, we need to build more nuclear plants, end of story. Then we need to give the Nuclear Proliferation Treaty the finger, and reduce the amount of generated nuclear waste by a factor of 50 by reprocessing the fuel rods that are "spent" when they have only 98% of their fissionable material remaining. (Thank you President James "Fuckup" Carter".)


  7. Martin:

    Great write up.

    I am now wondering if now is the best time to get into certain alternate energy stocks? Technically, they are ripe for picking!


  8. Craig:

    It's actually much worse than you calculate. A fossil-fuel plant is dispatchable. It will generate electricity rain or shine, regardless of the weather or the time of day. In contrast, solar plants generate only when the sun shines. This means that a utility would still have to have a fleet of fossil-fuel plants in reserve equal to the full output of the solar plants you calculate would occupy 10% of Arizona. In the last week, with all the rain we've had here, we would have seen very little solar generation from all that surface area.

    Worse, solar power production peaks around noon, but electricity demand peaks in the Southwest in the late afternoon when folks get home from work, turn up the air-conditioning, and start using computers, videogames, stoves, and other electric appliances. By 6:00 p.m. demand is near peak and solar generation has fallen to 10-20% of mid-day levels.

    Until someone figure out a way to store the electricity generated by alternative technologies, the best they can do is reduce fossil fuel consumption at a pretty high cost, but they cannot replace fossil-fuel
    generation. ... Of course all fossil fuel is really stored solar energy, collected millions of years ago by plants.

    Re hydroelectric power. Although this is truly renewable, storable, and dispatchable, it does not qualify as "green" or "renewable" electricty under the standards in place in most jurisdictions.

    Pumped-storage hydroelectric plants take advantage of the lower generation costs of nuclear and coal power by using the tubine-generators to pump water back into the upper reservoir when demand is low and then generating electricity with the turbine/pumps when demand is high. This is one conceivable way to store solar energy, but suitable sites are hard to find and environmental issues are hard to overcome.

  9. Ron H.:


    Are you aware that the projects in California have run afoul of the Sierra Club? Here's one example:

    You couldn't make up a story with richer irony. Green promoters vs. green preservers.

  10. Dr. T:

    The technology is not ready for prime time and have significant costs that weren't mentioned:

    The dishes and engines will require constant maintenance: the reflective surfaces must be cleaned and polished; the mechanisms for pointing the dish at the sun must be cleaned, lubricated, and calibrated; the Stirling cycle engines will need routine maintenance and periodic replacement.

    The costs of an energy storage system need to be added in, unless the setup is only designed for daytime power. In that case, a 24/7 power plant (fossil fuel, nuclear, or hydrodynamic power) will still be needed, so why bother installing an expensive solar farm?)

    The costs of power conversion (to high voltage A/C) and power transmission (the solar farms will be in the middle of the desert but the power is needed in distant cities) also need to be added.

    Yes, fossil fuel and nuclear power plants have fuel and maintenance costs, but the high capital costs and maintenance costs of solar farms would pay for many years of fuel.

    At the present time, the only solar energy technology that is cost effective (in warm, sunny areas) is passive solar water heaters. All other solar technologies are inefficient and are not economically viable: they survive only because of government subsidies.

  11. hanmeng:

    It doesn't matter how much it costs! The gummint will pay. Where does that money come from? The rich (defined as those with more money than I have).

  12. IgotBupkis:

    > The technology is not ready for prime time and have significant costs that weren’t mentioned

    This tech will never be ready for prime time -- it is and will always be a niche technology.

    This technology is one that LOOKS cool as opposed to actually functioning. In order to make it work, you need a certain minimal area of collective surface -- that is to say, the area of the dish x however many dishes has to equal a certain amount. This is tied to something called The Solar Constant, and it's near enough to 1kW/sq.m for back-of-the-envelope calculations. This is not a "trickable" number -- you can't engineer around it, make improvements past it, futz with it in ANY WAY -- you cannot possibly get any more energy than that no matter how inventive your engineering -- it's an inherent natural constant like "acceleration due to gravity".

    There's a fairly extensive piece on the matter here, but, the short form: If you want to replace the USA's power generation you will need to cover a land surface area (i.e., the area of those dishes x the number of dishes) of five BILLION square meters. How much is that?

    Try 4/5ths of the land surface area of the entire STATE OF DELAWARE.

    What? You only want 20% generation? Ah, so, covering only ONE FIFTH of the land surface area of an ENTIRE US STATE -- even "a small one" -- with glass, concrete, metal, and (possibly) "little blue cells", is A-OK with you? You have no problem with such a massive project?

    The only solar tech that MIGHT be useful on a large scale is one called Ocean Thermal, which uses the vast surface of the ocean as a solar collector. It's pretty inefficient but it MIGHT be made to work. So of course it's not one we're putting any real money at all into... Lonnie Johnson has developed the Johnson Thermo-Electrochemical Converter System (JTEC) that is remarkably efficient at extracting energy and it shows some promise in this arena, as well.

  13. IgotBupkis:

    > but a few hints plus the name of the company “Stirling Energy Systems” seems to point to that answer). Other concentrator technologies focus on boiling water, so this a new approach to me.

    I mentioned it above, but there's an even newer tech that should be particularly relevant, invented by Lonnie Johnson, the NASA engineer who is better known for making himself rich by inventing the Supersoaker water gun.

    He's invented a breakthrough electrical-thermal engine, the JTEC, that should give Stirling Engines a run for their money.

    It's not going to make the tech actually cost-effective (short of OTEC applications) but it's still a cool concept. The PopMech article linked to above details how it works. The man's smart as hell.

  14. Noumenon:

    I just wanted to say you are one of my favorite bloggers right now. You talk about all important issues, you're based on facts, you're frequently right. Even though the only times I ever post are to disagree with you, you change my mind quite a lot.

  15. brad f:

    I wish that lowering energy consumption and limiting the wastage of energy would be promoted more.There could be an immediate and substantial drop in energy use if energy efficiency techniques were studied and used more on a widespread scale.The same goes for the use of water.It's obvious to me that there has to be dramatic lifestyle changes for the masses of the developed world unless someone comes up with some type of free energy system.

  16. markm:

    My expectation is that the developers will bank the subsidies and walk away when the things break down. Which might be as soon as the first desert windstorm...

  17. Charles Kirkland:

    for shairing. I’ve copied it into the story above, to give it more attention.