Today I got into a dispute about biofuels with Helmut Burkhardt, a physicist and member of Science for Peace. I came home and read a paper he has prepared on the subject, then concluded that there is a tenable middle ground between our two positions. As he wrote me later in an e-mail:
“Here is my philosophy, which I share with the Swedish ‘Natural Step Group’: politicians, economists, and sociologists have a large degree of freedom in making relevant choices, as long as they are inside the limits set by the laws of nature. With respect to using biofuels, the economic arguments are good if applied to using biomass wastes. However, biomass wastes can only supply a few percent of humankind’s energy needs, and any large scale energy plantations are in direct competition with food production, and detrimental to biodiversity, which stabilizes our vital ecosystem; furthermore, energy farming requires large amounts of biologically productive land, fertilizers, and lots of water for irrigation. All of these are in short supply on this planet.
“Yes, this ‘green energy’ from biofuels sounds so attractive; it would solve the peak oil problem and prevent climate change at the same time. Unfortunately, it is one of those inappropriate myths that need to be exposed. – There are other non-nuclear solutions.”
Burkhardt’s arguments are based on his calculations about the total use of power by human beings: an average at present of 2300 W per person per day. Insolation is the amount of solar radiation reaching a given area. Using the global average insolation, Burkhardt calculates the average human being’s daily energy consumption as equivalent to the insolation of ten square meters of the planet’s horizontal surface. Of course, the satisfaction of human needs will vary according to the efficiency of the methods used for collecting this solar radiation. Solar cells and wind are quite efficient. Indeed, humankind’s present energy needs can be met with solar collectors of an area about 30 square meters per person on buildings or on dry land.
But ethanol — a fuel made from plants — is less efficient. For one reason, not all the photons absorbed by a plant perform photosynthesis. Also, some of the photons are reflected. Moreover, photosynthesis requires respiration, which requires energy. Hence, Burkhardt concludes that some 300 square meters per person of biologically productive land is required to supply the present energy needs of humankind with biomass fuel— a figure that is about ten times less efficient than solar collection panels. Even after that, one must subtract the energy costs involved in harvesting, transforming and processing the crop into fuel. Taking those factors into account, Burkhardt estimates that if we replaced the 2080 W per person now supplied by fossil fuels and nuclear energy with biomass energy, we’d need to use more than 4000 square meters per person of biologically productive land. Since that is not available on Planet Earth, Burkhardt concludes that it is irrational to count on ethanol for significant answers to our energy problems.
Okay. I cannot contest his calculations; I am no physicist. The other writers whom I have read do not calculate efficiency in terms of the amount of Earth’s surface that could yield energy via the different technologies of conversion. Instead they estimate how many units of energy must be expended to obtain one unit of fuel. In those terms, a quantity of sweet crude oil yields a net energy payoff of 100, whereas ethanol is estimated at only 1.34. (Using a different indicator of efficiency, it seems that corn-based ethanol has a positive energy balance of about 20,000 Btu per gallon.)
However, nowhere does Burkhardt distinguish between ethanol made from conventional sources (the starch in corn and other food products) and from cellulose. Though at the present, collulosic ethanol cannot be produced competitively with fossil fuels, the technology is being developed quickly and will vastly expand the amount of material that can be used — agricultural waste (corn stover, straw, etc.), as well as industrial and municipal solid wastes (paper sludge, garbage, etc.). Indeed, an estimated 40% to 50% of the feedstock would come from such wastes. And cellulosic ethanol yields more energy than the corn version. A fact sheet prepared by Lee R. Lynd and Lester Lave reports:
“The ratio of energy output to fossil energy input is favorable (> 4) for production of cellulosic ethanol, and can be expected to improve further as the technology matures. Fossil energy inputs for production and delivery of cellulosic energy crops are modest, e.g. estimated at about 5% of the energy content of the feedstock for switchgrass production, and inputs for waste cellulosic feedstocks are potentially lower still. The energy content of unfermentable process residues is greater than the energy than required for conversion to ethanol in the current designs, with the excess representing an attractive source of electrical power. The combined energy yield of ethanol and power is over 50% of the energy content of cellulosic biomass for current designs.”
Still, even if the input-output ratio of ethanol were as low as 1:1, there are occasions when it would be useful. Ordinarily, of course, any fuel that did not create more energy than it consumed would be worthless, but that is not always the case. Take, for example, the use of wood to make alcohol. Wood is not nearly as portable as alcohol, so under certain circumstances you might even be willing to use two BTUs of wood to get one BTU of ethanol, if the price of gas goes much higher.
I don’t disagree completely with Helmut. He says we cannot replace oil entirely with ethanol, and I agree. Nor would I want to do so. However, it has certain important advantages — especially in the short term — that he seems to overlook. First, it can be produced and used right away (see photo of such a plant), whereas other alternative fuels will require a huge re-tooling. Every car on the road can already use fuels with 10 percent alcohol content, and with a little, inexpensive refitting, we could even use 85% ethanol fuels – pumped right into our existing cars at our familiar neighborhood gas station. No other existing fuel will work for transportation. Of course, we’re not thinking of using it to heat houses or make electricity, so the need for it will never be as great as Burkhardt’s worst case scenario.
But the main reason why I am so enthusiastic about ethanol is that it will help liberate us from oil dependency soon, while potentially doing the best favor possible for the poorest countries in the world. The Doha Round was started for the explicit purpose of giving the developing countries some of the benefits of globalization, Every knowledgeable economist, so far as I know, agrees that the most important factor holding the poor countries back is the prevalence of agricultural subsidies in the rich countries. By enabling farmers in Canada (and Britain, the US, France, and especially Japan) to earn a good livelihood from harvesting an additional crop — cellulose for alcohol — each year, we will be able to eliminate agricultural subsidies and give the Developing World the opportunity actually to develop. That should matter as much to us as the discovery of a new and abundant source of cheap fuel.