This is about as off-topic as the mold issue. You've been warned. On Mon, 1 Oct 2001, Harmon Seaver wrote:
Biodiesel and bioethanol are horribly inefficient as far as conversion of solar energy and agricultural area is concerned. Large scale agriculture is not exactly environmentally neutral. They're extreme niche or gimmick fuels at best.
Where do you get that from? Are you saying that farmers aren't growing canola oil at a profit? Farmers are also growing corn and that corn is turned into ethanol at a profit.
No. I'm saying if you use bioethanol, biodiesel or oil made from agricultural products you're milking a negligable fraction of the solar constant (1.4 kW/m^2 flux hereabouts), even solar constant at the bottom of this gravity well (varies greatly). Plus, you kill soil, reduce biodiversity, contaminate ground water, reduce ground water level plus cause salination in susceptible areas, burn energy for machines, fertilizer & Co and create waste. There are also less tangible but nevertheless real factors such as high material fluxes, associated pollution, perpetuation of Carnot cycle machines and agromafia. What we need is sufficient control of molecular self-replication that we can use photons directly for photosynthesis or water photolysis. Before we'll get that, we'll have to settle for conventional thin-film and polymer photovoltaics, electrolysis and photoelectrolysis/photosynthesis. I would think that CuInSe thin film would do very nicely today if facade-integrated, before we get polymer.
http://journeytoforever.org/ethanol.html
Ethanol is a highly efficient fuel. A study by
Energy density of ethanol is about half of gasoline. You *can* use it in a fuel cell or a fuel reformer, but methanol is easier. Methanol <-> synthesis gas conversion is really clean.
the Institute of Local Self-Reliance in the US found that using the best farming and production methods, "the amount of energy contained in a gallon of ethanol is more than twice the energy used to grow the corn and convert it to ethanol".
So, assuming these people haven't been pulling data straight from their ass, you have to burn half of the ethanol you would get from a square meter of a field in order to do it. Not counting the presence of said field, the agricultural infrastructure and the agrohol plant.
The US Department of Agriculture says each BTU (British Thermal Unit, an energy measure) used to produce a BTU of gasoline could be used to produce 8 BTUs of ethanol.
Now this says something else than journeyforever folks said. 8:1 is something else than 2:1.
The non-profit American Coalition for Ethanol says ethanol production is "extremely energy efficient", with a positive
Energy efficient as compared to what exactly? Nuke, fossil, photovoltaics, wind? And, of course, energy is only a very small part of the picture.
energy balance of 125%, compared to 85% for gasoline, making ethanol production "by far the most efficient method of producing liquid transportation fuels".
Now, it's only 125%. Very strange numbers, these.
If you are refering to the paper done by Pimental, that study was seriously flawed (so much so that one might think it was paid for by big oil) and thoroughly debunked. See: http://journeytoforever.org/ethanol_energy.html
I do not refer to the study of Pimenthal, just seat of the pants ecology and 8th class highschool level physics. I don't have time to google for this stuff, but I'm sure you'll find enough references as to why bioethanol and biodiesel are hardly a silver bullet. -- Eugen* Leitl <a href="http://www.lrz.de/~ui22204/">leitl</a> ______________________________________________________________ ICBMTO: N48 04'14.8'' E11 36'41.2'' http://www.lrz.de/~ui22204 57F9CFD3: ED90 0433 EB74 E4A9 537F CFF5 86E7 629B 57F9 CFD3