Stanford Professor Assesses Best Energy Options

The best ways to improve energy security, mitigate global warming, and reduce the number of deaths caused by air pollution are blowing in the wind and rippling in the water, not growing on prairies or glowing inside nuclear power plants, says Mark Z. Jacobson, a professor of civil and environmental engineering at Stanford.

And "clean coal," which involves capturing carbon emissions and sequestering them in the earth, is not clean at all, he asserts.

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. The paper with his findings will be published in the next issue of Energy and Environmental Science but is available online now. Jacobson is also director of the Atmosphere/Energy Program at Stanford.

"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," Jacobson said. "Ethanol-based biofuels will actually cause more harm to human health, wildlife, water supply and land use than current fossil fuels." He added that ethanol may also emit more global-warming pollutants than fossil fuels, according to the latest scientific studies.

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. He recommends against nuclear, coal with carbon capture and sequestration, corn ethanol and cellulosic ethanol, which is made of prairie grass. In fact, he found cellulosic ethanol was worse than corn ethanol because it results in more air pollution, requires more land to produce, and causes more damage to wildlife.

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 United States, 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 a high blend of ethanol called E85.

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 United States; and virtually no water consumption. 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. 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."

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