I don't think the DOE is trying to confuse. To a first approximation, ethanol doesn't make any net contribution to CO2 when burnt as fuel if it is prepared from organic material grown for the purpose.
A farmer plants, say, sugar cane. The cane grows, using sunlight to convert CO2 and H20 to cellulose and sugars. Later, the cane is decomposed in a fermentor. Microbes may be used. They digest the material, gaining energy and structure for themselves, excreting alchohol (ethanol) and some CO2. The alchohol has less energy than the original cane, but it is more convenient. It can be poured and stored.
When the alchohol is burnt in a car, the circle is closed. The sun is powering the car, which is only returning the Co2 'borrowed' from the atmosphere by the sugar cane. The claim that this produced 90% net less CO2 must allow for the production process, which might consume some oil or whatever.
It can be argued that the same occurs when we burn oil, only the CO2 that is returned was 'borrowed' millions of years ago. That was when CO2 levels were much higher than they are now, and temperatures warmer. Earlier still there was very little free oxygen in the atmosphere. It came from the excretion of early plants!
I, too, doubt that ethanol will make a large contribution to our transport fuels, although it already is used as an additive in gasoline in the US. Photovoltaics do seem exciting. I have read they are getting close to being economically viable. With respect to nuclear power, I think that it should be re-evaluated in light of Co2 warming.
All large power stations use water-evaporative cooling, and this too has its problems. Which brings me (finally!) to ERC, I don't think their cells need this. Biomass is a potential fuel for them, but again, I don't think this will be a panacea.
aj
PS. The Third World.
This is their point: they are an afterthought. On a per capita basis they are way behind us in the production of CO2. Currently we are the ones that matter! We can't hope to get them to agree to limit their production while we're still way ahead of them and doing nothing ourselves. This, it is true, is politics. Shall we get back to ERC? |
