Cellulosic ethanol, which people from President-elect Barack Obama to struggling farmers from his home state view a promising biofuel, is actually worse than much-criticized corn ethanol because cellulosic ethanol results in more air pollution, requires more land to produce and causes more harm to wildlife, a major study has found.
The energy alternatives "that are good are not the ones that people have been talking about the most. And some options that have been proposed are just downright awful," said Mark Z. Jacobson, a professor of civil and environmental engineering at Stanford University, in a paper that reviewed and ranked major proposed energy-related solutions to global warming, air-pollution mortality and energy security.
"Ethanol-based biofuels will actually cause more harm to human health, wildlife, water supply and land use than current fossil fuels," he said, adding that ethanol may also emit more global-warming pollutants than fossil fuels, according to the latest scientific studies.
Jacobson has conducted the first quantitative, scientific evaluation of the proposed major energy-related solutions by assessing not only their potential for delivering energy for electricity and vehicles, but also their impacts on global warming, human health, energy security, water supply, space requirements, wildlife, water pollution, reliability and sustainability.
His findings indicate that the options that are getting the most attention are between 25 to 1,000 times more polluting than the best available options. His findings were published in this month's issue of Energy & Environmental Science.
The Most Promising
The raw energy sources that Jacobson found to be the most promising are, in order: wind, concentrated solar (the use of mirrors to heat a fluid), geothermal, tidal, solar photovoltaics (rooftop solar panels), wave and hydroelectric.
Jacobson, who is also director of the Atmosphere/Energy Program at Stanford, recommended against nuclear, coal with carbon capture and sequestration, corn ethanol and cellulosic ethanol made from prairie grass. Granted, cellulosic ethanol can be made from other sources and those were not studied.
To place the various alternatives on an equal footing, Jacobson first made his comparisons among the energy sources by calculating the impacts as if each alternative alone were used to power all the vehicles in the U.S., assuming only "new-technology" vehicles were being used.
Such vehicles include battery electric vehicles (BEVs), hydrogen fuel cell vehicles (HFCVs) and "flex-fuel" vehicles that could run on E85 -- a blend that's 85 percent ethanol and 15 percent gasoline.
Wind was by far the most promising, Jacobson said, owing to a better-than 99 percent reduction in carbon and air pollution emissions; the consumption of less than 3 square kilometers of land for the turbine footprints to run the entire U.S. vehicle fleet (given the fleet is composed of battery-electric vehicles); the saving of about 15,000 lives per year from premature air-pollution-related deaths from vehicle exhaust in the U.S.; and virtually no water consumption.
The Least Promising
By contrast, corn and cellulosic ethanol will continue to cause more than 15,000 air pollution-related deaths in the country per year, Jacobson asserted.
Because the wind turbines would require a modest amount of spacing between them to allow room for the blades to spin, wind farms would occupy about 0.5 percent of all U.S. land, but this amount is more than 30 times less than that required for growing corn or grasses for ethanol. Land between turbines on wind farms would be simultaneously available as farmland or pasture or could be left as open space.
Indeed, a battery-powered U.S. vehicle fleet could be charged by 73,000 to 144,000 5-megawatt wind turbines -- fewer than the 300,000 airplanes the U.S. produced during World War II and far easier to build. Additional turbines could provide electricity for other energy needs.
"There is a lot of talk among politicians that we need a massive jobs program to pull the economy out of the current recession," Jacobson said. "Well, putting people to work building wind turbines, solar plants, geothermal plants, electric vehicles and transmission lines would not only create jobs but would also reduce costs due to health care, crop damage and climate damage from current vehicle and electric power pollution, as well as provide the world with a truly unlimited supply of clean power."
Jacobson said that while some people are under the impression that wind and wave power are too variable to provide steady amounts of electricity, his research group has already shown in previous research that by properly coordinating the energy output from wind farms in different locations, the potential problem with variability can be overcome and a steady supply of baseline power delivered to users.
The Most Damaging
He described biofuels as "the most damaging choice we could make in our efforts to move away from using fossil fuels." He said the money going into biofuels would be better spent promoting energy technologies that cause significant reductions in carbon dioxide emissions and air-pollution mortality, "not technologies that have either marginal benefits or no benefits at all."
During the recent presidential campaign, nuclear power and "clean coal" were often touted as energy solutions that should be pursued, but nuclear power and coal with carbon capture and sequestration were Jacobson's lowest-ranked choices after biofuels.
"Coal with carbon sequestration emits 60- to 110-times more carbon and air pollution than wind energy, and nuclear emits about 25-times more carbon and air pollution than wind energy," Jacobson said. Although carbon-capture equipment reduces 85 percent to 90 percent of the carbon exhaust from a coal-fired power plant, it has no impact on the carbon resulting from the mining or transport of the coal or on the exhaust of other air pollutants.
In fact, because carbon capture requires a roughly 25-percent increase in energy from the coal plant, about 25 percent more coal is needed, increasing mountaintop removal and increasing non-carbon air pollution from power plants, he said.
Nuclear power poses other risks. Jacobson said it is likely that if the U.S. were to move more heavily into nuclear power, then other nations would demand to be able to use that option.
"Once you have a nuclear energy facility, it's straightforward to start refining uranium in that facility, which is what Iran is doing and Venezuela is planning to do," Jacobson said. "The potential for terrorists to obtain a nuclear weapon or for states to develop nuclear weapons that could be used in limited regional wars will certainly increase with an increase in the number of nuclear energy facilities worldwide."
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