Powering the Future: A Scientist's Guide to Energy Independence

by Daniel B. Botkin

  How much energy do biofuels provide today?

  Biofuels currently provide only about 3% of America’s energy (Figure 9.2). Woodburning makes up 67% of this total (this includes wood wastes such as bark and otherwise unusable wood burned to provide heat in the production of paper); wastes 21%, and agrifuels only 12%. But ethanol from crops is increasing. In the United States in 2004, ethanol replaced approximately 2% of all gasoline (1.3% of its energy content). By 2007, it replaced 2.8%.14,15 Worldwide, crops currently provide 13.5 billion gallons of ethanol a year.16 Biofuel production has increased rapidly in the nations of the European Union, reaching 8 million tonnes in 2008.17

  Figure 9.2 Biofuel use in the United States as of 2008. (Source: Energy Information Administration, Renewable Energy Consumption and Preliminary Statistics 2008)18

  Fuel from waste

  Atlanta-based Biomass Gas & Electric LLC, a developer of biomass-driven power plants, recently signed a 20-year agreement to supply power to Progress Energy Florida, a subsidiary of Progress Energy Inc., based in Raleigh, North Carolina. The deal involves a wastewood-to-energy plant not yet built that is expected to produce 42 megawatts. “We joke here in the office that [the Southeast] is the OPEC or Saudi Arabia of biomass,” says Biomass CEO Glenn Farris.19

  With increasing frequency, waste used to produce biofuel is from agricultural products that were grown and used for food or some other purpose and were then simply dumped. As a fuel, these serve a dual purpose: We don’t need to set aside land to grow them since they’ve already been farmed for food, and we don’t need to find places to dump them.

  Take cooking oil, for example. An Asian restaurant named Pearl East, in Manhasset, Long Island, New York, used to pay $40 a month to get rid of its old cooking grease from making egg rolls and fried noodles.20 But starting in December 2007, as part of a new environmental initiative by the Great Neck Water Pollution Control District, the restaurant’s used grease and oil have been collected in 55-gallon drums and sent, at no charge to the restaurant, to the district’s plant, where it is converted into biodiesel fuel and used to power the district’s vehicles and generators. Not only does this get rid of a nasty waste, but also the fuel is much cheaper for the government, whose costs to transport and process it work out to only 70¢ a gallon, versus more than $3 a gallon to purchase diesel fuel at the commercial pump. Keep in mind that this wasn’t grown to be used as fuel. It was grown for food and is now a waste product that can be used as fuel.

  An interesting and amusing story by Susan Saulny in the New York Times on May 30, 2008, told of a “bandit” who “pulled his truck to the back of a Burger King in Northern California one afternoon” and “dunked a tube into a smelly storage bin and...vacuumed out about 300 gallons of grease.” The police found 2,500 gallons of used fryer grease in his truck.

  The article goes on to say that the owners of the Olympia Pizza and Pasta Restaurant in Arlington, Washington, claim their 50-gallon grease barrel has been siphoned several times, and they are considering installing a surveillance camera. “Fryer grease has become gold,” an owner said, “and just over a year ago, I had to pay someone to take it away.” Used frying oil is now traded on the commodities market as “yellow grease.”21

  In some developing nations, garbage can be a strong energy alternative. Masada Resource Group LLC, a privately held Birmingham, Alabama, developer of waste-to-energy plants, says it is planning to raise $60 million to help develop and operate commercial-scale plants in Central and South America.22

  What crops are grown today to provide biofuels?

  Corn and sugarcane are producing the largest amounts of biofuels at present, but many other crops are proposed, some have been tested, and quite a variety are in production. These include standard crops such as cassava, coconut, potatoes, sugar beets, sorghum, soybeans, and wheat; oilseed crops such as sunflower, mustard, and rapeseed (especially popular in Europe to make biofuels); pistachios (becoming popular as a biofuel source in China); alfalfa (a legume); and grasses, including reed canary grass and four natural grasses of the American prairie: prairie cordgrass, switchgrass, Indiangrass, and big bluestem. Some trees, in addition to those grown for firewood, are also in production for industrial biofuels, especially hybrids of poplar (one of the fastest-growing trees, grown extensively in plantations in Europe, where it provides much of the lumber and paper).23 Mixes of natural or naturalistic vegetation are also proposed, such as American prairie plants.24 These crops-for-energy have two major products: vegetable oils, like cooking oil, that can be used directly as fuel; and ethanol, good old mountain dew drinkable alcohol (ethyl alcohol, scientifically, not to be confused with methyl alcohol, the poisonous “wood alcohol”) that has to be made with a distillery, as the people at Johnny Walker can tell you.

  Fuel versus food

  Biofuels may sound like the perfect solution to our fuel problems, but it is not—far from it. Consider the case of farmer Alfred Smith of Garland, North Carolina, who began feeding his pigs trail mix, banana chips, yogurt-covered raisins, dried papaya, and cashews, according to an article in the Wall Street Journal.25 The pigs were on this diet, Mr. Smith said, because the demand for the biofuel ethanol, produced from corn and other crops, had driven up prices of feed (the largest cost of raising livestock) to the point where it was cheaper to feed his animals our snack food. In 2007 he bought enough trail mix to feed 5,000 hogs, saving $40,000. Other farmers in the U.S. Midwest were feeding their pigs and cattle cookies, licorice, cheese curls, candy bars, french fries, frosted Miniwheats, and Reese’s Peanut-Butter Cups. According to the Journal, “Cattle ranchers in spud-rich Idaho were buying truckloads of uncooked french fries, Tater Tots and hash browns.” Near Hershey, Pennsylvania, farmers were getting waste cocoa and candy trimmings from the Hershey Company and feeding it to their cattle.

  Their problem was caused by competition with crops grown directly to be turned into fuels. We’ll call these agrifuels.26

  Proponents of agrifuels will search for more and more efficient methods to produce them, requiring less area and lower costs. But with agrifuels, Mother Nature sets an upper limit, because of the laws of physics and the limits to how much energy can be produced by green plants, algae, and bacteria. Growing plants to turn into fuel, we might be able to approach the upper limits of the efficiency of Mother Nature’s photosynthesis, but we can’t do better than the laws of thermodynamics allow, nor better than those amazing and intricate devices inside the cells of green plants can do—the photosynthetic machinery of life. For this reason, we have to ask whether Mother Nature can compete well with approaches completely different from crops-for-fuel, in terms of both the area required and the energy we get back versus what we put in.

  According to David Pimentel, one of the world’s experts on the ecology of agriculture and on biofuels, if the total U.S. production of corn were used to produce biofuels rather than food, the ethanol produced would provide only 5% of today’s total oil consumption—2% of the total energy used—by the nation.27 Because corn doesn’t produce ethanol directly, as any home distiller can tell you, the corn has to be fermented and distilled, which requires considerable energy. As currently carried out, producing ethanol from corn takes 46% more energy than is contained in the resulting fuel. In other words, making fuel from corn takes energy; it’s not a source of energy. The same is true for ethanol from switchgrass, one of the native American grassland species that is being grown for biofuel, and rapeseed (the source of Canola oil). Ethanol produced from switchgrass or rapeseed is slightly less an energy sink than corn ethanol but still results in an energy loss rather than an energy source. The only benefit of the process is money made by agricultural corporations who received large subsidies for it.

  Others propose using America’s native grasslands to produce ethanol for fuel, but much of these are used for grazing, and the rest is important to biological conservation, soil conservation, and recreation. Still others suggest that agricultural “wastes”—stems, roots, and l
eaves that are not part of a harvested crop—should be used to make biofuels. But these organic materials are necessary for soil structure and fertility, to have productive croplands in the future, so this would be an unwise path to follow.28

  Elsewhere in the world, large areas of tropical rain forests have been converted to palm oil plantations to produce biofuels. In contrast to the crop plants and grasses of North America, palm oil appears to provide a net energy output of about 30%. But these plantations are replacing valuable tropical rain forests and threatening species such as orangutans.

  Basic considerations in judging the value of biofuels

  Whether, on balance, biofuels are good or bad depends on (1) which biofuel—biological waste, wood for household use, or agrifuels from wide-scale industrial farming; (2) how it is produced; (3) what that production competes with; and (4) how energy-efficient and cost-efficient the production process is.

  Judging a fuel’s efficiency

  Judging any fuel’s efficiency involves four factors: energy efficiency, area efficiency, cost efficiency, and carbon efficiency. We discuss the first three. The last needs a book of its own and goes beyond what we can discuss here; this is not to deny its importance.

  Energy efficiency is how much energy you get from a fuel compared with the amount of energy it took to produce that fuel. For a fuel to be useful at all, the efficiency has to be greater than 1 (the breakeven point, where it takes just as much energy to produce the fuel as you get out of it), and it should be a lot larger.

  Area efficiency is how much energy you get from each acre you use to obtain that energy. With biofuels, it is how many acres it takes to get the equivalent of a barrel of oil or gasoline from, say, corn or sugarcane. Does one crop use a lot less acreage than another? If so, then there are benefits to using the most area-efficient crop, because this leaves more land to grow food, or for biological conservation, or for housing, and so on.

  Cost efficiency is how much money you can get for a fuel versus how much it cost to produce it. This, too, should be greater than 1 if anybody is going to make money on it. But there’s an important caveat: In certain situations the cost efficiency may be less than 1 but the fuel is still worth it. For example, if you are sending a rocket to Mars and want to power the landing vehicle with a small nuclear generator, you will be willing to expend energy to develop and build and transport that generator even though that energy will never be returned, because the goal is not to produce energy but to acquire information. In fact, the cost efficiency of all current forms of space travel is zero. Other examples in which cost efficiency is secondary are the use of nasty wastes like old cooking grease for fuel rather than dumping them into the environment, and backpacking fuel for warmth and cooking on a camping trip—hauling it along may be a lot of work, but it’s worth it.

  The energy efficiency of biofuels is questionable

  For agrifuels—plants grown primarily for fuel—the exact energy efficiency is hard to determine because so many species are being used, tested, or proposed right now, and because accounting for all the energy used to produce a crop is complicated.

  For example, energy is used not only directly by the farmer to grow the crop, but also to produce the seeds he uses, transport those seeds to the farm, and transport water, fertilizers, and pesticides that the crop requires. Manufacturing farm machinery and transporting it to the farm also take energy, as do constructing farm buildings and manufacturing and transporting the materials that go into them. It takes energy to feed, clothe, and house the farmer and his employees and to transport them to and from the cropland. It takes energy to harvest the crop, transport it to where it will be converted into a biofuel, carry out that conversion, and then transport the biofuel to locations where it will be used.

  To make it even more complicated, some scientists count only the energy content of the biofuel itself on the positive side since this is the goal of the entire process. Other scientists add to that the energy content of all the remaining parts of the crop, including organic wastes and by-products, whether or not they end up being used as fuel. Thus, one careful analysis concludes that it takes 29% more energy to produce ethanol from corn than is contained in the ethanol.29 Another concludes that there is a 25% gain, but the gain includes the energy in animal feed, a by-product, and in this second case the scientists conclude that the environmental and social costs outweigh the benefits.30

  Studies of biodiesel fuels (where the crops yield vegetable oil that is then burned as fuel), too, differ widely as to whether they provide a net energy benefit. According to one analysis, biodiesel fuel produced from soybeans required 27% more energy than it yielded. Another study concluded that biodiesel produced “93% more usable energy than the fossil energy needed for its production,”31 but, again, the more optimistic estimates usually include energy that could be obtained from parts of the crop that are not intended to be used as fuel and generally aren’t.

  The bottom line on biofuel energy efficiency

  Many scientific studies conducted so far indicate that crops planted and harvested today to be turned into biofuels either take more energy than they yield or else provide only a small energy benefit. But there is a large range in the estimates, from a net energy benefit of 12 kilowatt-hours in a gallon of ethanol to a loss of 7 kilowatt-hours from each gallon produced.32 The difference seems to depend mainly on how one calculates the energy costs to produce the gallon of ethanol, not on the actual energy content of that gallon. Even when they do appear to provide a net energy benefit, the benefit is outweighed by environmental and economic consequences (such as erosion, food scarcity, and higher food prices).

  Proponents of biofuels argue that we don’t need to be concerned about net energy benefit; they say it just doesn’t matter. Instead, we need to compare only the energy content of biofuels with other fuels and the uses we can put each to. So, ethanol and biodiesel are better than coal simply because they can be used to power cars, trucks, and airplanes. But this argument requires that you suspend belief in the laws of thermodynamics, that you don’t care that to get corn ethanol or vegetable oils you burn more fossil fuels than they yield. The argument is absurd, and I have mentioned it only because this is likely to come up in discussions of this chapter. So let me make the point clear: If a chemical takes more energy to make than it yields, it is not actually an energy source. It may be useful as a product, or, as I’ve mentioned before, when one goes on a long hike and wants to carry fuel for cooking and warmth, or on a space trip.33

  The U.S. Energy Independence and Security Act (passed by Congress in 2007) calls for 38 billion gallons of ethanol to be produced from biofuels per year by 2022, an amount that equals a quarter of all gasoline consumed in the U.S. today.34 And no more than 40% of this can be provided by corn. The rest has to come from crops other than small grains. Even under the best possible conditions of weather, soil fertility, irrigation, and lack of crop diseases and pests, this would require at least 118 million acres, more than one-third of the U.S. land in crops in 2009, so this requirement will compete heavily with food production (Figure 9.3).35, 36

  Figure 9.3 How much energy does corn provide? Studies vary widely. Most recent studies show a positive net energy balance for corn ethanol. (Courtesy of Michael Wang, Center for Transportation Research, Argonne National Laboratory, personal communication)

  Crops grown to produce biofuels will tax the supply of water and phosphate fertilizers.37 There is already worldwide concern about the availability of freshwater, and crops grown to produce biofuels will place an additional burden on water supplies. Industrial agriculture makes use of large quantities of fertilizers, two of whose main ingredients are nitrogen and phosphorus. Industrial processes enable us to convert nitrogen gas in the atmosphere to nitrogen compounds for fertilizers, but phosphate rock is obtained from mines, and there are limits to its economic availability. Like fossil fuels, phosphate rock is distributed nonuniformly around the world. About 80% of phosphorus is produced in fou
r countries—the United States, China, South Africa, and Morocco38, 39—and the global supply that can be extracted economically is estimated at about 15 billion tons (15,000 million tons).

  In 2009, the United States obtained approximately 30.9 million tons of usable phosphate rock from mines, 85% from Florida and North Carolina, the rest from Utah and Idaho.40 In short, all of our industrialized agriculture—most of the food produced in the United States—depends on phosphorus from just four states!

  Total U.S. reserves of phosphate rock are estimated at 1.2 billion metric tons. However, obtaining the 30.9 million tons of marketable phosphate rock from U.S. mines in 2009 required removing 120 million tons of rock from the mines, and in the next few decades phosphorus is likely to become even more difficult to obtain.

  According to the U.S. Geological Survey, in 2007 the price of phosphate rock “jumped dramatically worldwide owing to increased agricultural demand and tight supplies of phosphate rock.” And by 2009 “the average U.S. price was more than double that of 2007,” reaching as much as $500 a ton in some parts of the world.41