Why are we not looking elsewhere for siting options for solar energy? The nation’s hundred million rooftops could host solar PV collectors. The land under the roofs is already disturbed, and the visual impacts of the buildings on which they sit is already accepted. As a bonus, the power can be used near the generation point, meaning no new powerlines, with their hundreds or thousands of miles of land disturbance and visual impacts, would be needed.

I’m no engineer or green energy expert, but it makes sense to me. The balance of the energy could come from all the cool technologies proposed by all those smarter than me who have commented here.

Some of these monster coal plants are in the desert, the “Navaho” plant located in Maracopa county, Arizona, for example, is located in an area of high sunshine.

I have speculated that these plants could be converted to CSP, with biochar backup, with the biochar brought in through biochar log pipelines from elsewhere. Another backup possibility is to bring biomass energy to the site as carbon monoxide or hydrogen, via pipeline.

It seems possible to bring steam to a central power plant from solar power towers, using very long steam lines buried inside insulated conduits. These lines could be constructed to have a certain amount of thermal mass, themselves, and so constitute sensible heat storage. So, you get heat storage and steam transmission capability in one retrofit. One cement that might be able to withstand the extreme conditions of these insulated conduits is a family of cementitious materials known as “geopolymers”. Another high temperature solution would be to simply construct these conduits of firebrick, insulate them with something like pumice, and fill them with rock, gravel, and sand, as sensible heat storage for the steam lines coming from an array of solar power towers surrounding the power plants.

As solar production and biochar use is ramped up, coal consumption could be ramped down. As carbon storage or sequestration capacity is increased, the plant becomes increasingly carbon neutral, finally becoming carbon negative when completely converted to solar with biochar backup, enhanced sensible heat storage, enhanced thermal efficiency via oxyfuel combustion and a topping cycle, and deep injection of captured CO2.

If we depend on the coal and utility industries, this will never happen, even though it might be technologically feasible. We need to seize the coal fired power plants, and massively convert them by fiat into carbon negative power plants. CSP could certainly help, for those power plants located in the desert, such as the Navaho plant in Arizona.

http://www.inference.phy.cam.ac.uk/ withouthotair/ c30/ page_236.shtml

[JR: Try Google!]

From google, I learn that total US electrical generation capacity is about 1 million megawatts.
http://www.eia.doe.gov/ cneaf/ electricity/ epa/ epat2p2.html

Thus, the solar energy study areas can generate only about 10% of current total US electrical generation, and it is a bit misleading to state it as 30% of household electricity consumption, ignoring other consumption.

[JR: It was their stat. But people typically write about electricity savings/generation in terms of American homes -- this would provide enough power for about 30 million -- and hence the percentage. Not misleading. Quite standard.]

I think solar thermal can do better than that, and when they plan the transmission corridors, they should look at the best sites on private lands as well as on public lands.

[JR: Of course it can, this is just solar plants currently proposed on U.S. lands.]

That is a really strange position. I assume it must be because the term “environmentalist” comes with some unwelcome baggage – long-haired, unwashed people who break into coal fired power stations. That sort of stuff.

The point I an trying to make is that curbing CO2 is all about the environment. Nothing else. You can’t see it, smell it and it’s not about to suffocate anyone, but CO2 threatens to become the biggest environmental disaster of all time.

Joe -if you are not an environmentalist then no-one is. On the other hand, if you somehow deny your intetest is environmental then that makes me wonder if climate change is just a convenient vehicle for pushing other, unrelated agendas. I do hope not.

But how does that compare with the nation’s TOTAL electrical consumption, including industrial as well as household?

[JR: Try Google!]

I don’t understand this statement. If you are lobbying against climate changing CO2 emissions because they change the climate then you are an environmentalist. We all share the same environment, even if you only profess concern over it’s impact on US civilisation.

[JR: Well, you might read some of the posts on this blog, starting here. I am a physicist and a technologist who studied physical oceanography at the Scripps Institution of Oceanography. I am not "lobbying against climate changing CO2 emissions because they change the climate." I am working as hard as I can to avoid catastrophic impacts on humanity from GHG emissions. If you are suggesting that everybody should be an environmentalist, that is a different matter.]

Bit worried about hybrid gas/solar. This approach addresses energy but not climate change. The acid test is whether such a solution leaves us with a clean energy system BEFORE all carbon has been extracted. This one does not aim to do that.

We’ve spent a trillion dollars on the Iraq war, and we’re told we can’t afford clean energy. The US has more military spending than all the other countries combined. When Don Rumsfeld was Secretary of Defense, he owned 80 million shares of a defense contractor that was awarded a huge defense contract. The Wash Post, the NY Times, they all thought that this sort of obvious corruption was ok, and hardly even noticed.

We spend much more on health care than any other country, our health care providers are much more profitable and they spend enormous amounts of money on lobbying. Yet our health care is ranked far below many other countries.

We just spent enormous amounts of money bailing our financial institutions who lost enormous money investing trading toxics asserts that were fraudulently rated AAA.
To get an idea of the mindset of these guys, the CEO of Merrill-Lynch bought a $35,000 toilet for his executive bathroom with his bailout money.

We spent about $500 billion dollars on foreign oil last year alone, and that’s only going to go up. That’s money flowing out of the country that we don’t get to use to invest in renewable power, grid improvements, and alternative transportation. We can’t afford electric cars, but if we had them we could save $7 trillion over the next ten years. Huh?

All of this waste and yet we are told over and over that we can’t afford clean energy. It’s complete nonsense. It took only two days to install solar panels on my roof and I cut my electric bill in half. Now I’ve got an electric car, and I’ve cut my fossil fuel usage by 70%.

My life is exactly the same as before, I am NOT living a humbled life.

The US has done basically nothing to move to clean energy and already we are told it’s too expensive.Shouldn’t we try a few simple steps first? Then we can evaluate how much it’s costing and how much it’s saving? Shouldn’t we try get our house in order and stop giving all our money away to the rich people running the defense, health care, financial, and oil industries?

Wonderful news about the solar. Sounds like a lot of it. It’s been known for a long time, since the 1980’s of course, that CSP on this sort of scale was possile.

Why not use biochar for backup fuel? Coal log pipelines could be constructed from forested or agricultural areas to carry pelletized biochar compressed into logs. Or, railroad transport could be used, as well. This would make these CSP baseload plants carbon neutral.

Another possible carbon neutral energy transport medium is carbon monoxide derived from biomass, believe it or not. A old process known as COSORB, which was originally proposed to transport combustible gas from coal mines to power plants, could be updated and used to transport carbon monoxide hundreds of miles, without being worried about hydrogen embrittlement of pipelines.

If you’re not worried about hydrogen embrittlement, and I believe there has been some progress in this in the past couple of decades, there is always hydrogen derived from biomass as a transport medium, for a carbon neutral backup fuel.

Another possible backup for solar thermal is geothermal hot dry rock, called engineered geothermal these days, I think.

And, of course, there is always the option of just adding more sensible heat storage on to CSP plants.

Finally, there is the possibility of using phase change materials for increased heat storage. There has been work done on this in the past, but successful large scale heat storage by a phase change material (which would be melted, for example, absorbing heat as it melts, then would recrystallize and give off heat upon solidifying) has not yet been achieved, I think.

Many technologies are possible to provide heat storage for solar themal power plants, or for subsequent storage of the electricity generated by such plants.

Flywheel storage of electricity is another technology, proposed long ago, with a great deal of potential, which has not been developed for utility scale energy storage but which probably could be with effort and engineering development.