Energy futures.

• Position: List

By now, you've heard it in a thousand political speeches--the shopping-list-style recitation of newfangled-sounding alternative energy sources and technologies. Clean coal! Solar and wind! Switch grass!

Yet few people take the trouble to examine the energy technology field as a whole, comparing a cross-section of future sources across the same set of objective criteria, especially price. The following is reason's attempt to rectify this gap, giving consumer and policymaker alike a quick guide to alternative energy.

Supercritical pulverized coal

Pulverizing coal is the predominant method for generating electricity in the U.S. and around the world. In a pulverization plant, coal, after being ground to the texture of flour, is blown into a furnace to burn. This converts circulating water into steam, which turns the blades of a turbine to produce electricity. "Supercritical" units heat up to 1,000 degrees Fahrenheit and make steam at 3,600 pounds per square inch.

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Technology invented: The first coal-fired electric plant was Thomas Edison's Pearl Street Station in lower Manhattan, which began operations in 1882. Pulverized coal plants began coming online in the 1920s.

Federal research dollars since 1976: $27.4 billion ($5 billion on pollution control) for all coal technologies (all monetary figures are in 2009 dollars)

Carbon emitted: 0.86 metric ton per megawatt-hour

Cost per plant without carbon capture: $2.8 billion

Estimated cost with carbon capture in 2025:$3.9 billion to $4.7 billion

Production cost of a kilowatt-hour without carbon capture: 6.5 cents

Estimated production cost of a kilowatt-hour with carbon capture in 2025: 8.5 cents to 10 cents

Waste: The U.S. burns about 1.1 billion tons of coal annually, producing 125 million tons of solid waste, consisting of fly ash (fine particles), bottom ash (sand-like particles), slag (glass-like crud), and flue sludge. A 1,000-megawatt plant typically will emit 2,500 tons each of sulfur dioxide and nitrogen oxide, plus around 700 tons of particulates. Eighty percent of coal-produced slag is used for sandblasting or as grit on roofing shingles; 40 percent of bottom ash is used as gravel substitute; 44 percent of fly ash is used as a Portland cement substitute, and flue gas scrubber residues are converted into synthetic gypsum wallboard. Other waste includes rock removed from surface and underground mines and water drained from mines.

Advantage: Domestic supplies are abundant, at over 275 billion tons.

Disadvantage: Produces excess waste and greenhouse gas.

Representative example: The $1.8 billion plant in Longview, West Virginia, will produce a maximum 700 megawatts by 2011.

"Clean coal"

Integrated gasification combined cycle (IGCC) plants mix coat with steam and oxygen to produce a synthetic gas. The gas is burned much like natural gas to fire a turbine and produce electricity. Waste heat from the gas turbine is then used to produce steam to run a steam turbine. This "combined cycle" of gas and steam power is more efficient than conventional coal-fired plants.

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Technology invented: Coal gasification was invented by a Scottish engineer in 1792 and first licensed in the U.S. to what became the Baltimore Gas Company in 1813. As natural gas production became possible, coal gasification fell out of favor. New IGCC plants started operation in the U.S. in the 1990s.

Federal research dollars since 1976: See entry for supercritical pulverized coal.

Carbon...