joema said:
Ivan's point was only a much higher yield feedstock is scalable to meet the necessary demand, and algae is one of the only (maybe THE only) feedstock with the necessary yield.
As far as I know algae has only been shown to produce a high yield per acre-year under laboratory conditions where it is was grown in a sealed container, in an ideal climate (good insolation), and supplied with concentrated CO2 from the exhaust of a coal-fired power plant. I expect that corn, and just about any other crop, would produce a spectacularly increased yield per acre-year under similar conditions. It seems reasonable to try and exploit available sources of concentrated CO2 for biofuel production, perhaps using algae, but this is not what Ivan is trying to do. He is trying to grow algae using aeration. Unless and until someone here explicitly claims, and then cites a credible reference (or makes a plausible argument) to substantiate that claim, that there is a positive net energy balance for biodiesel production from algae grown using aeration, then we should dismiss that claim. Don't you agree?
Per capita energy consumption is not relevant to the issue, which is whether any biofuel can be scaled upward sufficiently to supply a major % of U.S. or global transportation energy. It's not per-capita consumption that matters, it's total consumption.
The SA article presents an analysis of U.S. biofuel supply and demand, but not world biofuel supply and demand. This website presents data showing that there is a great variation in per capita energy consumption from one country to another:
http://www.hubbertpeak.com/nations/percapita.htm. It is not reasonable to assume that the analysis presented in the SA article for U.S. biofuel supply and demand should also apply to the world as a whole.
The difference is VASTLY too much for conservation to make up the difference.
When the petroleum supply finally runs out, conservation
can and
will make up the difference. .
That doesn't mean conservation is wrong or shouldn't be used, only that it's inadequate to compensate for the insufficient yield from current biofuel feedstocks.
Ha ha...conservation is infinitely adequate for the task, I assure you.
As the Scientific American article highlighted, ethanol (for example) can only supply a few % of U.S. transportation energy. On a global basis, the situation is similar.
Per capita energy consumption in the U.S. is 697 times greater than it is in Afghanistan for example, and average per capita energy consumption in the rest of the world is several times lower than it is in the U.S.. So, again, it is not reasonable to assume that the analysis presented in the SA article for U.S. biofuel supply and demand should also apply to the world as a whole.
This means conservation would have to make up at least 80% of the current consumption, which is about 100 quadrillion BTU/year. It's simply not possible to reduce global transportation energy consumption by 80% via normal conservation measures within a timeframe meaningful to the problem.
Oh yes it
is possible, and it
will happen when the oil runs out. btw, I am not just talking about "normal" (I assume that you mean "voluntary") conservation measures, but also involuntary conservation measures and technological advances.
It would require a total restructuring of all society, akin to an asteroid hitting the earth, a nuclear war, or a global plague which decimates humankind.
Good. The sooner the better. I doubt that the advance of science in general and Moore's law in particular will be greatly hindered by such a restructuring. So what if we all wind up either riding bicycles or busses to work at some point in the future?
The issue is NOT what % of transportation energy is currently supplied by a given biofuel feedstock. Rather it's what biofuel feedstock (if any) can be scaled to the gigantic industrial level required to supply a major % of U.S. or world transportation energy. With ethanol from corn, soy, switchgrass, etc. it's clearly impossible.
I will not discuss "world transportation energy" with you using only the SA article as a basis. It is not reasonable to assume that the analysis presented in the SA article for U.S. biofuel supply and demand should also apply to the world as a whole.
Algae at least is theoretically possible from a yield standpoint, plus can be grown on non-arable land so it doesn't displace existing crops.
You keep talking in terms of "areal yield" and ignoring what I have said about the requirements for concentrated CO2 vs. aeration to produce biodiesel from algae. I am quite sure that fission has a vastly superior "areal yield" to biodiesel from algae in terms of kWh/acre-year. Don't you agree?
That doesn't mean biodiesel from algae is the solution or is guaranteed to work.
Ivan claims otherwise. He is claiming that algae
can satisfy the need for crude oil. I have asked him to preface his remarks with "I think", or something like that, but so far he hasn't done that. So, I
reject his claims as they stand. Don't you agree?
Ivan Seeking said:
there is only one crop that can produce enough biofuel per acre-year to satisfy the need for crude oil: Algae.
joema said:
However ethanol from conventional feedstocks are guaranteed to NOT work, i.e, provide a major % of U.S. or global transportation energy.
Ethanol displaces a marginal % of petroleum consumption which is useful, and this will become increasingly important as the supply of petroleum dwindles away. Who has claimed otherwise?