Alternative Energy – Solar Power

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By Ed Caryl

Can we provide enough energy to power the world using alternative sources, such as wind, solar, or bio-fuels?

This is a question that has largely been ignored, in hopes that the answer will prove to be in the positive. This article is the first in a series, taking the question one technology at a time.

      Figure 1. Solucar PS10 solar concentrator power plant near Seville, Spain. Source: Wikipedia Commons

http://en.wikipedia.org/wiki/File:PS10_solar_power_tower.jpg

Four problems with wind and solar power are: the area needed for the plants, energy storage when the wind or the sun is not available, transmission costs, and energy losses in storage and transmission. For solar power in the U. S., the power is available in the southwest of the country, and the power is needed in the northeast. In Europe, sunshine is abundant in Spain, but not so much in Germany. In general, environmentalists oppose additional transmission lines nearly everywhere. But let us assume that the transmission problem is solved. Is there enough area to collect sunlight to support all the energy needs? Let us take the area where this author lives as an example.

New Mexico – area 314,460 km2 – insolation 7 kWh/m2/day

Not all of the area is usable. Mountains, forest, wilderness, National Monuments, farm and urban areas, military training areas, bombing and missile ranges, are off limits. Perhaps 10% of the land area might be available for solar if all the ranchers are bought off and the environmentalists are bound and gagged. That likelihood seems very remote, considering that every patch of sagebrush seems to harbor an endangered lizard. (In California the animal holding up solar plants is the Desert Tortoise).

The power available on 10% of the area of New Mexico is:

31,446,000,000 m2 X 7 kWh/m2 X 365 = 80,344,530,000,000 kWh or 80.345 PetaWatthours (PWh)

This sounds like plenty of energy. The U. S. currently uses about 30 PWh per year. But there are problems. This figure is for a two-axis solar concentrator if it runs at 100% efficiency. The real efficiency of a solar thermal plant is in the range of 8 to 15%, about the same as photovoltaic panels. The Sierra SunTower plant in Lancaster California generates 5 MW peak, with no thermal storage, occupies 20 acres of land, about 81,000 m2, or about 62 W/m2. It is in a zone with 7 to 8 kWh of solar radiation available. That is an efficiency of about 8%. The Andasol 1 and 2 plants in Spain claim 15% annual average efficiency with 8 hours of thermal storage.

So, using the above efficiency figures, 10% of the area of New Mexico would supply 6 to 12 PWh of electricity or 20 to 40% of the energy needed for the US. We would need to build the same number of plants in at two or three more states, California, Nevada, and Arizona would be candidates.

Storing the heat for use at night is the next biggest problem. With current technology the most efficient thermal storage (molten salt) stores heat for about 8 hours. The salt used is a mixture of sodium and potassium nitrate (fertilizer). It takes about 28,000 metric tonnes of salt to support the Andasol 1 plant for 8 hours of heat storage. Sodium and potassium nitrate are also known as saltpeter, the oxygen source in gunpowder. Now visualize a terrorist-driven airliner full of jet fuel (the carbon source) crashing into the storage tanks at one of these plants. It would be the equivalent of a small tactical nuclear bomb.

The total world production last year for nitrate fertilizers was 154 million tons, but most of that was ammonium nitrate. Chile, the chief supplier, only produced about a million tons of sodium and potassium nitrate. If all one million tons were used for energy storage, that would supply thirty-six 50 MW plants, or 0.018 PWh of electricity annually, 0.06% of that needed for the whole US, and less than 0.15% of that needed for all the above plants in New Mexico. One hundred years of Chilean production would build 6% of the needed solar plants for the U. S. alone.

There are other heat sinks that can be used, but they have problems of their own. The most efficient heat storage is the above described nitrate salts. The other proposals are more costly or have less volume specific heat capacity. One of the cheapest is concrete blocks with embedded pipes. But the structural stability of the pipes and concrete over many temperature cycles is a problem, and the mass needed is 250% of that needed using nitrate salt. For a plant the size of Andasol 1, 70,000 metric tonnes of concrete would be required. That volume takes up ground area, lowering the overall plant efficiency, and requiring more area for a given power output.

Let’s say we have beaten the above problems. We have paved 10% of four western US states with solar plants of 15% efficiency and are providing more than 30 PWh of electricity to the US, all the power we need. The problem then is that we are dumping nearly 200 PetaWh of heat into the environment, almost seven times what we are dumping now, and twice what the whole world is producing. What will happen to the temperature? The southwest US will be uninhabitable at something like 10 or 15°C hotter than at present. If the same thing is done in Europe, the rain in Spain will no longer fall anywhere. It will bring on the catastrophe that Hanson et al have been warning us will happen.

A solar power solution requires vast areas, with a high environmental cost that probably cannot be paid, and the waste heat load would make any projected CO2 warming look benign. Solar plants are not the long-term solution to our energy requirements. 

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33 responses to “Alternative Energy – Solar Power”

  1. Stop Common Purpose

    Some eco-loons think that solar energy is a viable option in the UK.

    We are up against pig-headed fraudsters and con-artists.

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  3. DirkH

    European court grants environmental movements the right to sue against infrastructure projects in Germany.
    http://www.spiegel.de/wirtschaft/soziales/0,1518,762276,00.html

    By now, only people who were personally affected could sue. Now, our friends from Greenpeace, WWF, DUH and BUND can sue themselves. Against everything. Expect a complete standstill.

    1. DirkH

      This means that some new coal power plants already under construction will be sued against, probably resulting in the demolition of some of the projects; but it will also result in a deluge of lawsuits against all kinds of new wind turbines or large scale solar arrays. The various green splinter groups are known to fight against *every* project. Of course, feedlot operators, railways, airports and every other industrial development will not be spared.

  4. DirkH

    Ed, your efficiency numbers look good. But one caveat: When you talk about the extra heat dumped into the environment, you have to consider how much heat is created without solar panels already. IOW, it’s the increase of albedo that is important when one wants to estimate the change in microclimate (minus the energy that is exported via electricity lines).

    1. Ed Caryl

      True, but the albedo of a solar plant, whether PV or concentrators, is designed to close to zero. In desert areas, the original surface is around 0.5. That’s still a lot of heat.

  5. Jimbo
  6. Jimbo

    My scenario ‘C’ says that there will be a calamity before politicians get back to their scenses.

  7. Bob in Castlemaine

    Anyone have a realistic understanding of how geothermal stacks up as far as the total quantity of energy that “may” be practically extractable?

    1. Ed Caryl

      There are only a few geothermal fields that can be practically tapped. Most of them are being tapped now. I’ll take a look at the subject in a future article.

    2. Beano

      I know of one working geo-thermal plant. It’s based at the bottom of an active volcano. Generates enough power to supply a few villages. The volcano is just one crater located in an active caldera. (With the emphasis on active)

      Geo Thermal power was touted for Australia by the usual dreamer academics and greeners. Unfortunately with those people, they have no sense of economic rationality. The plants would be too far away from population centres and the cost of reticulation lines would be prohibitive.

  8. solar power

    I Know solar is very important in future.It has many benefits.As of now, solar power and solar related devices are expensive. But it may be reduced if most of the people start using it. Let us see the future of solar power

    1. Beano

      Solar powered energy has been around for fifty years. Battery technology has been around for over 100 years. If there were major advances to be found in these two technologies they would have been found by now.
      They both have limited constraints enslaved by by physics. T.S.I. also remains a major constraint on solar panels.
      Both technologies are very dirty in production and this has been moved to third world countries where pollution is hidden out of the way.

      The only real advances have been made by electronics technology and miniaturization. This has led to devices that use very little power so existing battery and solar technology can be used. However you can’t get around physics in the need for big power consumption.

  9. M White

    “Renewables can fuel society, say world climate advisers”

    http://www.bbc.co.uk/news/science-environment-13337864

    If you want to live in the third world

  10. Paddy

    As an American optimist I expect Obama to be replaced in 2012. Moreover, Republicans can achieve veto proof majorities in both houses of Congress. Climate alarmism will be relegated to the dustbin. For the first time a pragmatic energy policy based upon fossil fuels and nuclear energy can be developed. Expect us to drill, drill, drill!

    The UK, Germany and several other EU nations seem determined to destroy their economies. I don’t wish you ill, but if you cannot prevent the energy train wreck that is OK too. We will regain our economic domination again.

    We will start demonstrating our exceptionalism again. We can protect you from yourselves if you give us the chance to do so. Otherwise, learn to become comfortable bowing to the east and praying five times daily.

    1. DirkH

      What completely bewilders me that to this day there is no sane economical debate in Germany. I find such debates in all the anglo-saxon media, but not in Germany. This doesn’t mean our company bosses don’t know economics; it only means that there’s no public debate that deserves the name. It always gets reduced to public debt / Euro crisis stuff but no analysis of the subsidy regime, the interference with the free market (if there is one in Europe!)… The studies that showed that for every Green job, several real ones disappear get no mention even though we have Spain as the poster child for this… The connection between rigging the market and reaping mass unemplpyment is not made…

      That’s one of the reasons why i’m optimistic for the USA (and the rest of the Anglo-Saxon world) as well. You have FAR better analysts.

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  12. gallopingcamel

    P.Gosselin,
    I loved your excellent piece above which dovetailed nicely with something I posted on the same day. Economic sustainability is essential. Great minds think alike?
    http://bravenewclimate.com/2011/05/15/solar-power-in-florida/

    However, as a physicist one statement you made rather spoiled things for me. You said:
    “The problem then is that we are dumping nearly 200 PetaWh of heat into the environment, almost seven times what we are dumping now, and twice what the whole world is producing. ”

    That is not a valid argument against solar power as the heat you are talking about is coming from the sun. If the solar panels were not there a similar amount of heat would be absorbed. While solar collectors are designed to absorb as much energy as possible, they fall well short of being “Black Bodies” and sometimes reflect more energy than the surfaces they are covering.

    1. DirkH

      “Silicon happens to be a very shiny material, which means that it is very reflective. Photons that are reflected can’t be used by the cell. For that reason, an antireflective coating is applied to the top of the cell to reduce reflection losses to less than 5 percent.”
      http://www.thesolarplan.com/articles/how-do-solar-panels-work.html

      1. DirkH

        And here’s another one, adding wicked AGW logic to justify PV.
        http://www.scientificamerican.com/blog/post.cfm?id=the-albedo-effect-2009-10-27
        “The increase in heat absorption is a one-off climate forcing, equivalent to adding a certain amount of carbon dioxide to the atmosphere. By comparison, fossil power generation is an ever-increasing climate forcing, since each unit of energy entails the emission of more carbon dioxide. So there is some breakeven point beyond which the solar panels help the climate.”

        If you agree with that argument, I’d suggest you become a journalist.

        1. DirkH

          …because the author didn’t understand the carbon cycle. BTW, your tour of the power plants is a fascinating read; thanks for posting the link!

  13. Ed Caryl
  14. Ed Caryl

    The article was talking about solar concentrators, not PV panels. The design of both types, trough concentrators and power towers, absorb the power into tubes or panels that are as black as possible. In a desert environment the original ground is usually about 50% reflective. The difference will result in heat in the environment.

    1. DirkH

      One could also say that any solar power collector *must* be optimized to have an albedo as low as possible – whether it is shiny blue when glanced at from the side does not matter; only capture of direct sunlight is important. It must appear as black as possible when looked at from the sun.

      Similarly, the ocean has an albedo of nearly zero when the sun is in the zenith. One can see that in satellite fotos – the ocean vertically under the satellite appears black, not blue.

  15. Solar Panels Cecile

    Yeah this is quite an issue : can we provide enough green energy to power the world? The problem is the space, solar and wind power need space, a lot of space, and all the country are not equal in space. As well, not all the country in the world has the same sunshine or wind or even the same population amount. There will be inequalities that’s for sure. But it’s not because this is a difficult aim to reach that we should not keep trying!

    Cecile

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