Biofuels are a complex matter and Giampietro and Mayumi use almost 300 pages to eviscerate it in all its aspects. The main point of their analysis is based on fundamental physics: the efficiency of photosynthesis is low and the result is that the areas needed for cultivation are large. If we are thinking of amounts of biofuels comparable to the present needs for transportation, the task is simply unthinkable: there would be no space left for food production. As the authors flatly state at page 128 of the book, “Full substitution of fossil energy with agro-biofuels is impossible.”
The large area needed is only one of the problems with biofuels. More in general, agriculture is a good technology for producing food, but it is terribly expensive in terms of the resources it requires. It needs land, water, fertilizers, pesticides, mechanical work; all supplies that normally come from fossil fuels. Taking all that into account, the EROEI (energy return for energy invested) of biofuels is generally low; unless the invested energy is supplied by low cost human labor, as it is the case for Brazilian sugar cane. Apart from Brazil, the need of an energy subsidy in the form of fossil fuels makes biofuels unable to deliver their promise of being a “sustainable” technology. They can’t help us in reducing our dependency on fossil fuels nor in reducing the emission of greenhouse gases in the atmosphere.
Of course, the biofuel story is more complex than that and Giampietro and Mayumi examine the whole spectrum of possibilities in their book. Are there better biofuels? Or, perhaps, ways of using the present form of biofuels in a more effective way? Yes, of course; there is the promise of “second generation” fuels (cellulosic ethanol) and the possibility of cultivating marginal areas, unsuitable for food production. But the physical factors of the problem don’t change much and, right now, biofuels and conventional agriculture are already competing for land and resources. One of consequences may be the increase increase in food prices that we have been seen during the past few years.In the end, what do we want to do, exactly, with biofuels? Do we really think that the way to solve our energy problems is to use an inefficient technology to support an already inefficient transportation system? The only explanation I can think of for so much emphasis on biofuels is that, once a bad idea is implemented, it starts to gain momentum and then it becomes nearly impossible to stop.
Read the whole post at Peak Oil: Exploring Hydrocarbon Depletion
11 comments:
I wonder if oil from algae is worthwhile?
http://en.wikipedia.org/wiki/Algae_fuel
I think that all these things can and probably will be part of a mix of energy sources. The super-efficient stove that uses wood has wide application some areas, for instance.
Algae ponds could be another decentralized energy source that meets local needs. I would rather see decentralized production and distribution rather than centralization and consolidation, which tends to reinforce power structures and encourages further privatization of the commons and continuous monetization through rents.
Tom,
Algae are at their productive maximum in fairly low light conditions. Under that situation, algae ponds are not the best methodology. Algae ponds surface area is in a 1:1 ratio with the land surface are they occupy. The key is to maximize the amount of algae per unit light. Therefore, thin vertical bags of a circulating mix of air/co2/water work the best - also algae species can be chosen to maximize the final end product. Different species are good for different end products - some estimates of oil production using this methodology are as much as 20,000 gallons of diesel equivalent per acre
See video
What I was thinking of, Clonal, is that out here in farm country there are watering pond all over the place that filled with algae just going to waste and are considered in the way. Same with farm refuse like cornstalks. There are all sorts of potential biofuels now passing as waste that could be composted, converted to energy, etc. Of course, that is not cost effective commercially or they wouldn't be lying around. But if there were some decentralized way of dealing with them locally, they would be used, for sure.
What brings this to mind is being in Third World countries and watching people scoop up every bit of waste that could possibly be used, almost fighting over it. There was no manure in the streets problem when horses were the chief means of transport either. It was scavenged for fertilizer. Same now with road kill in many parts of the world, even in some parts of the US today.
Tom,
Pond algae is uneconomic, because of the costs of collection. Not cost effective enough in terms of total effort. Hence Ugo Bardi's comment. You are much better off farming fish (that feed off the algae) in that pond. There is still a lot of work keeping it ecologically balanced, but that effort is cost effective, and much more remunerative.
Tom,
Also see for example John Todd Ecological Design
Good point, Clonal. What I am also thinking of is two fold,
First, small farmer's were remarkably versatile and creative in solving problems with materials at hand. Sometimes makeshift and even Rube Goldberg, but its worked and required no outlay of money, which was scarce. And they didn't even have duct tape until recently. BTW, have your ever seen the Red Green Show? It's a favorite here in Iowa for that very reason.
Secondly, it is possible to innovate to make things economically that are now perceived as not so, because our our approach to what is economical, usually involving economies of scale. But there are people willing to do things that are not economical in order to gain more freedom from "the man." There is a whole global movement devoted to this. Some very clever people are involved, and there are whole communities that revolve around creating an alternatives.
Very nice. Here the direct link there to About Eco-Machines
Also John Todd videos
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