Alternate fuels: community ecology informs energy policy

There's little doubt that we need to move America off of its addiction to rapidly depleting fossil fuels. The challenge is that our current energy infrastructure is heavily dependent on there being a common currency of energy; cars and trucks all run on different formulations of the same product, factories and households tap into the same electrical grid.

While the electrical grid is basically agnostic to the source of the electricity, replacing petroleum products will be trickier. The reason we need them is that cars and trucks need to carry their energy source with them. While hydrogen or ethanol could both replace that benefit of gasoline, only one will win out, because gas station owners might be prepared to retrofit their equipment to handle one new fuel, but are unlikely to spring for two or three. Since biodiesel is already establishing itself in the marketplace as an almost-perfect replacement for diesel fuel (biodiesel can corrode some hoses), station-owners won't move until the winner is chosen. And of course, no one will move to either fuel source until station owners upgrade their pumps.

Gasoline, biodiesel, ethanol and hydrogen are basically ways of storing and transporting energy. Hydrogen can be produced with water and electricity; if electricity were cheap enough and the conversion efficient enough, you could refuel your car from a garden hose. Ethanol is stored solar energy from plants, and gasoline is stored solar energy from very old plants.

Hydrogen is a gas, and would require special equipment to be feasible. Coupled with a renewable source of electricity, it could be emissions neutral, since the output of the car would be clean water, the same as its input. Ethanol has the advantage of being liquid, so much of the transportation infrastructure could be kept intact, with upgrades to protect pipelines from corrosion, for instance. If farming and transportation were emissions neutral, ethanol would be too, since all the carbon released by burning it came from the air while the crops were growing.

Of course, farming and transportation are not emissions neutral.

I don't know now where I found this link, but thanks to whoever pointed me to an article in Chemical & Engineering News asking Ethanol—Is It Worth It? The debate centers on the claim that it takes more energy to produce a gallon of ethanol than the gallon of ethanol gives back. By some calculations, it takes about 13 gallons of oil to produce 10 gallons of ethanol, by which argument it would be more efficient to just burn the oil.

As is so often the case, the story is more complicated. To get that number, David Pimentel included a wide range of energy uses that go into ethanol production, energy uses which probably would not stop if we produced less ethanol, or even if we grew less corn. On the other hand, government estimates that claim you get 10 gallons of ethanol at a cost of 7-8 gallons of gasoline ignore necessary energy use. That suggests that the debate is a push.

Other argue that Pimentel's isn't even asking the right question:

Bruce E. Dale, a chemical engineering professor at Michigan State University, backs the USDA numbers and has applied Pimentel's methodology to making gasoline. He found gasoline production has a 45% net energy loss, worse even than Pimentel's charges for ethanol [net losses of 29% for distilled ethanol, 50% for cellulosic]. He also looked at generating electricity from coal and found a net energy loss of a whopping 240%.

He asks rhetorically: Does that mean coal shouldn't be used to make electricity? Dale says the debate over net energy loss or gain is "irrelevant."

While there are many good arguments against coal-powered plants, I'm inclined to agree with Dale's point here.

One of the reasons that ethanol is almost sure to emerge as the winner over hydrogen is that it is produced from corn grown in, among other places, Iowa – home of the first caucus in the nation. So long as Iowa gets to pick the next president, politicians will be looking for ways to make corn more valuable, and ethanol has certainly been fitting that bill lately. Early work on the new Farm Bill is already running into tough questions about how much to subsidize corn farmers who have benefitted from rising prices driven largely by demand from ethanol producers.
Corn is the default source of ethanol in the US, but the success Brazil has had in becoming energy independent has come from its production of ethanol fuels from sugarcane. That's a much better source of ethanol, but high tariffs on sugarcane and ethanol produced from it mean that we cannot produce nearly enough ethanol from that more efficient source. Those sugar tariffs are another perk for corn farmers, who sell corn to produce high fructose corn syrup, and to sugar beet farmers.
Setting aside its energy costs, corn farming is also not the best thing for soils, nor for waterways. Fertilizers and pesticides get into waterways and damage ecosystems, intensive plowing and corn's nutritional requirements destroy the topsoil, and the water needs can deplete precious aquifers.

Luckily, there are other options. The most exciting development, one that is supposedly very close to commercial viability, is cellulosic ethanol. Conventional ethanol production is a fermentation of sugars into alcohol, followed by distilling. Since most of the plant has no sugar, it is turned around as waste, for use as fertilizer or animal feed. Cellulosic ethanol is produced by specially produced enzymes that break down the cellulose that makes up most of a plant's structure. Most animals can't digest cellulose; bacteria in the guts of termites and ruminant mammals help them break down cellulose, given time.

At this point, cellulosic ethanol is still quite expensive, though the companies that produce the enzymes are making improvements at regular intervals, and government funds and researchers have been dedicated to moving that research forward.

The benefit of this technique is that it doesn't require sugary parts of the plant, almost any plant material could be used. President Bush's confusing comments about switchgrass in last year's State of the Union referred to this approach to ethanol production. Switchgrass is a fast-growing grass that can grow in arid areas without needing extensive fertilizing, irrigation or plowing.

And in another example of the importance of ecological science to agriculture, research by the famed Dave Tilman at the University of Minnesota has found that high-diversity grasslands can produce more biomass more quickly and with lower fertilizer inputs than agricultural landscapes. The land where the experiment has been running since 1994 was too poor for farming, but the products of the land could produce more energy than cornfields.
In addition to being able to produce substantial amounts of cellulosic ethanol, planting grasslands stored carbon dioxide as rootmass underground. This rebuilds the soils and sequesters carbon out of the atmosphere. In their experiments on degraded soils, switchgrass was no better than other crop monocultures.

And where crop monocultures like corn or soy is, as discussed earlier, net carbon producers, these grassland plots were net carbon comsumers, taking in more carbon from the atmosphere due to carbon sequestration than they release when converted to fuel and burned.

Dr. Tilman and his colleagues calculate that widespread planting of such low-intensity, high-diversity plots could cut global carbon emissions by 15%. This would allow ethanol to be produced on lands like those participating in the CRP program, though with regular harvests of the naturally occurring species. Such grassland plantings could also replace wheat in drought-prone areas such as western Kansas.