Jed Rothwell wrote:
With IR photosynthesis alone, and no sunlight photosynthesis, you might pull this off with less than 1000 acres.
The conceptual problem that all of us have - when comparing single cell life with "agriculure" is that the two are radically different in a few vital categories, yet at the same time very similar is some respects. This can lead to false assumptions.
We tend to think too much in terms of either/or. Either the organism uses photosynthesis or it uses chemistry - IOW derives energy by digesting chemicals which are not fully oxidized.
When using chemical energy and no light - in order to reduce CO2, which is the common "raw material" in most life (that is to de-oxidize CO2 and reuse the carbon) there would need to be a "free" supply of partially reduced chemicals. These need not be carbohydrates - yet in order to derive what "seems like" it is more than 100% of the solar energy which is falling on the pond, the source is chemical. Coal ash is part of that source. NOx is another part of that source. Solar photons can be catalytic without being required to be a significant "energy source" in themselves.
With Algae (broadened to include all single cell life) there are strains which can do many things well, some of then not requiring light - including producing enzymes which can derive energy from minerals in the exhaust stream from buring coal, including sulfur, iron, silicates, phosphates and calcites. These minerals have already been partially or fully reduced by the combustion itself, and they have plenty of "free" energy to be harnessed by algae which does not require sunlight.
A ton of smokestack effluent might have 10% of more partially reduced minerals and soot, including significant amounts of NOx if hight temperature combustion is allowed. The nitrogen oxides, in particular, also have energy content to add into the mix, in addition to the nitrogen needed for proteins. Many of these could be transitory.
All in all, it may be possible for a pond to produce what appears to be more net energy of biofuel - than if 100% of the solar energy falling on it were converted into that fuel.
That is true - even if in fact only 5% of the solar photons were being actually converted. For this to happen the other 95+% which gives the appearance of "too much efficiency" must be coming from a combination of chemicals in the ash, NOx and waste heat energy. The solar would be catalytic - not primary energy.
After all - only one kilowatt of solar per meter^2 on average may fall on the pond over daylight but 50 kilowatts of heat energy may be dissipated by the same area over the 24 hour day ... maybe not in the pond configuration but in the tube setup used by MIT.
The beauty of all of this is that the very things which we do not want in the air we breath are what the algae "want" in order to double their mass every few hours.
Jones
