Keywords: Reed Jensen; SOLAREC; hydrogen production; electrolysis; carbon monoxide; concentrating solar power; Klaus S. Lackner; carbon hydroxide; capture carbon dioxide; Richard Branson; Science for Peace; Pugwash.
Last week I was enthralled by “Terra Preta,” the Amazonian soil that can save the world’s agriculture while providing us with a terrific carbon sink. This week I’ve encountered two more inventions that go far toward solving climate change. I found them on a TV broadcast that’s a lot better than the average of its kind. It’s called “The Great Warming,” and the third episode is the one with the best stuff. I have taped it and can share that episode with friends. There are two proposed machines that particularly intrigued me and which I’ll describe here. Unfortunately, the short segment on each one of them only stimulated my curiosity without giving many details so I’ve done further investigation through good old Google.
First, there’s the SOLAREC installation (see photo/graphic) created by Reed Jensen and his daughter Anne. A working prototype (maybe even several versions) are already functioning in the desert near Los Alamos, New Mexico, where Jensen used to be a laser specialist with the National Laboratory. (I don’t even like to think about his former job, which must have been related to nuclear weapons somehow.) When the sun is shining this machine produces both electricity and hydrogen fuel without using any fossil fuels whatever.
Until now the problem with the vaunted “hydrogen economy” has been that the hydrogen is produced by electrolysis, which cracks water into hydrogen plus water. But this electrolysis requires electricity, which is generated mainly by fossil fuels. For this reason, there’s no advantage in hydrogen cars, so long as fossil fuels are required to produce the hydrogen. “You’d do better just to run your diesel engines,“ says Jensen.
His invention, on the other hand, is truly green. Not only does the production take place entirely without fossil fuels, but the hydrogen that it produces costs only half as much as the fuel made by electrolysis.
The electricity production is done through the same method that has been applied elsewhere: concentrating solar power. An array of mirrors is set up to move around to keep up with the sun. It looks a bit like a satellite TV dish, but the function is entirely different. Here the sun’s rays focus on a small chamber that concentrates heat, which powers a turbine. I’m not completely sure of this, because it’s not described at all – probably because this electricity production aspect is not the interesting part. It gets exciting only when we turn to the hydrogen production aspect.
To produce hydrogen, you want solar rays (tightly focused by the mirrors) to create intense heat in the small chamber, where it splits carbon dioxide to create carbon monoxide plus oxygen. You release the oxygen into the air, but you must combine the carbon monoxide very quickly with water. (Speed is essential, lest the whole process go backward.) Neither the film nor the Internet description is completely adequate — neither source gives the chemical formula — but from my weak memory of high school chemistry, I infer that it probably goes like this: H2O + CO -> CO2 + 2H. Thus you get some carbon dioxide back at the end, in addition to this separate hydrogen, which is the name of the game. You hang onto your two hydrogen atoms until the sun sets and leaves you needing electricity in the dark, whereupon you burn the hydrogen to generate power. Indeed, you will probably even have some surplus hydrogen to sell to, say, service stations that provide fuel for hydrogen-powered cars.
Jensen says that a 100 square meter mirror SOLAREC system produces about 24 kilowatts worth of hydrogen and 25 kilowatts of electricity, making it nearly 48 percent efficient. Other systems that generated only electricity with concentrated solar power are about 30 percent efficient.
His company, Renewable Energy Corp (RECO), produced a dish that cost about $30,000. It operated for about two years. The next version was slated to measure about 20 square meters and to be located south of Santa Fe. RECO’s web site mentions a potential installation in Hawaii, which would produce 1 megawatt of power with about 40 solar concentrators. It would cost about $5 million and would power about 300 homes. At that volume, electricity would cost about one-fourth as much as electricity produced by photovoltaic electrolysis using solar panels. Or it would cost one-half the price of fuel produced by windmill/ electrolysis. Best of all, a SOLOREC plant will prevent the emission of about 100,000 tons of carbon dioxide emissions over its lifetime.
The company says that some of their customers will avoid the grid connection altogether. Grid customers, on the other hand, may order groups of 10,000 focusing dish, each one with a single turbine and fuel conversion plant.
Sounds good to me.
Meanwhile in New York City, Klaus S. Lackner has been working to develop a device that is not going to produce energy at all, but will remove carbon from the atmosphere for sequestration. The TV series The Great Warming also described his project, which is also described on-line.
The great thing about Lackner’s system is that it can immediately remove CO2 that is already ambient in the air, where it is causing global warming. You don’t have to capture it while it is being emitted from, say, a factory or a vehicle — in fact, that would be inefficient because then you’d have to transport the CO2 (probably through pipelines) to the site where it would be sequestered. Instead, let the air transport it for you. The novel point about Lackner’s scheme is this: you set up the device to capture the carbon from the air exactly where you’re going to bury it. It also doesn’t matter whether this CO2 is anthropogenic or of natural origins (as about 99 percent of it is). It all moves around in the wind, so it does not matter where it originated. You just want to remove an amount equal to the stuff that is being emitted elsewhere.
Lackner is not optimistic about being able to replace fossil fuel with sustainable sources of energy in a timely way. We are going to continue emitting greenhouse gases for quite a while, like it or not. But we can capture the CO2, starting pretty soon. In fact, with enough of his tall, “harp-shaped” towers, we could even reduce the atmospheric carbon dioxide levels to pre-Kyoto levels.
Apparently there are numerous chemicals that bind with carbon dioxide and therefore can be captured and sequestered. Lackner is proposing the use of calcium hydroxide— also called portlandite because of its frequent use in portland cement. This “slaked lime” apparently is available in ample quantities from limestone. However, Lackner is not committed to this particular chemical and says that probably other substances would work equally well or even better. The point of his paper is to show mathematically that the carbon dioxide capture from natural airflow is technically feasible at a rate far above the rate at which trees capture it.
Removing CO2 from one cubic meter of air and disposing of it will offset the effects of generating 10,000 joules of heat from gasoline anywhere in the world. Is this economically viable? Lackner says yes.. He points out that the kinetic energy of a cubic meter of air is 60 j. A windmill that operates by extracting kinetic energy from natural airflow needs to be two orders of magnitude larger than a CO2 collector that compensates for the emissions of a diesel engine that generates the same amount of energy. “Since windmills appear economically viable, this suggests that the capturing apparatus should not be too expensive to build,“ he argues. Indeed, he pursues other kinds of comparisons between alternative fuels and his scheme, always reaching encouraging conclusions.
“Average fluxes in desert climates accounting for weather and day and night are around 200 W/m2. Photovoltaic panels can capture maybe 25 percent of this flux. Under conditions of intensive agriculture, biomass growth can capture maybe 1.5% of this flux, and thus would rate at roughly 3 W/m2. typical unmanaged forest growth would fall far short of capturing even that much carbon equivalent. ...If one could maintain a flow of 3 m/s through some filter system and collect half the CO2 that passes through it, then the system would collect per square meter the CO2 output from 15 kW of primary energy. This is more than the per capita primary energy consumption in the US, which is approximately 10 KW. The size of a CO2 collection system would thus have to be less than 1 m square per person. Covering the same energy demand with wind-generated electricity instead would require an area at least a hundred times larger. ”
Lackner also calculates the probable costs. If the only costs were those involved in capturing and scrubbing out the CO2, it would add only about 50 cents to the cost of a ton of CO2 – but there is more involved than that. For example, there the cost of recovering the sorbent and releasing the CO2 in a concentrated stream ready for disposal. These steps are likely to be far more expensive than the capture itself, so that processing a ton of material will be measured in dollars, not cents. Citing an estimate by Gilberto Rozenchan of some $10 to $15 per ton of CO2, Lackner concludes that this is still a promising prospect for, “it would allow capturing the CO2 from gasoline for 9 – 14 cents per gallon of gasoline.”
No life-sized prototypes of this scheme have been built, apparently, but Lackner describes what they would look like. Each filter bank would be about as tall as a high-rise building, located in an airflow stream, not spaced close to other filters (for that would be inefficient).
“The cost of a collection tower, even if it exceeded the $9 million implied by a cost of $3,000/kW for its electricity generating cousin [the wind turbine, I think he means] would still be extremely cheap compared to the cost of the coal-fired power plant, which would be approximately $300 to $400 million.”
If the sorbent chosen is calcium hydroxide (Ca(OH)2), its output will be calcium carbonate, the stuff of which seashells are composed. Attached to the filter system, it will easily capture CO2 from the air; the expensive requirement will then be to recover the sorbent. However, Lackner thinks that other sorbents may be much cheaper than calcium hydroxide.
“Even a worldwide collection system does not have to be extremely large. Per person the cross sectional area facing the wind would have to be about 0.12 m. The area would increase to 0.65m per person if the world’s per capita energy consumption would reach the current US per capita consumption. At present rate, 380,000 collection units, each taking up 100 m by 100 m in land area could collect all the CO2 emissions from human activities. One would need one such unit (roughly two football fields ) for every 16,000 people. These units could share the land with other activities... The 380,000 units would have to be spread out over an area at least 530 km by 530 km, of which they would occupy 1.4%.”
I want to see this scheme elaborated. Who is ready to pay the bill for a prototype filter? Perhaps Sir Richard Branson. He has offered a huge reward (I think $1 billion) to the person who comes up with a practical way of capturing CO2 from the planet’s atmosphere. Maybe Lackner will win. (I hope so, though it does worry me slightly that his filters would capture CO2 but not the other greenhouse gases, such as methane and nitrogen. Perhaps someone else will work out a filter for them too.)
It seems to me that Science for Peace and Pugwash include a number of scientists who are qualified to review this proposal expertly. I intend to circulate this blog entry to several people in the hope that our organizations can take the initiative in lobbying for government support to experiment with these two remarkable inventions.