Here's the stuff of America's energy future: wood trimmings, cow manure, chicken litter, household trash and landfill gas.
Debris is becoming a hot commodity in some areas as the U.S. power industry seeks to lessen its dependence on fossil fuels amid growing global-warming concerns.
With renewable energy taking off, wind and solar power are hogging the limelight, but biomass-fired electricity is quietly making a comeback after a decade-long slump. Biomass is animal and plant wastes used as a fuel source.
In his State of the Union address, President Bush cited the need for biomass as a gasoline substitute. Yet 80% of biomass is now used for electricity and heat, says the Center for Renewable Energy.
Biomass plants burn the organic refuse to produce steam that turns generators. They already represent 1% of U.S. electricity capacity and 11% of renewables, says Cambridge Energy Research Associates. Biopower thus rivals wind and dwarfs other emerging renewables, such as solar and geothermal. Yet while wind power has been growing about 30% a year, biopower has been stagnant. Projects in development, though, would boost capacity 14% by 2009, CERA says. "They're starting to percolate," says CERA analyst Brandon Owens.
Wood-fired energy producers, which round up leftover, low-grade wood from loggers and saw and pulp mills, make up about 60% of the industry. Municipal solid waste, landfill gas, animal waste and agricultural waste constitute the rest.
Biopower took off in the 1980s, sparked by a federal law that encouraged small renewable energy projects. But since natural gas prices fell in the 1990s, biopower has struggled. It's rebounding thanks to rising natural gas prices and the prospect that Congress will cap carbon dioxide emissions from fossil-fuel plants to curb global warming. Wood and other organic matter emit carbon when burned, but they'd release the same amount if allowed to decay, and maybe more harmful methane if buried in a landfill. Biopower's advantage over wind, meanwhile, is that it runs nearly constantly.
"You're getting (power) pretty much 'round the clock and reliably," says Hal La Flash, renewable energy director for Pacific Gas & Electric in California, which gets 5% of its electricity from biomass.
Biopower also provides social benefits, such as disposal of animal wastes that otherwise would pollute groundwater, says Scott Sklar, former head of the defunct National BioEnergy Industries Association.
Hurdles for biopower
Yet biopower faces challenges. A pound of wood chips or household trash, for instance, yields a third to half the energy of the same amount of coal. That raises fuel costs so sharply that producers must scrape together their detritus from within a 75-mile radius to avoid high transportation expenses. That, in turn, limits supply. Capacity of an average plant is 20 megawatts, making it far less cost-efficient than a typical 500-megawatt coal plant. Most biomass plants are run by small producers that sell their power to utilities. The cost to produce electricity from biomass is about 25% more than wind and 90% more than coal, Owens says.
Uncertain supplies are another issue. In Burlington, Vt., a wood-fired plant has been running at 60% capacity, partly because machinery can't be rolled into muddy forests.
The industry, though, is blossoming as it eyes fresh revenue. Twenty-three states make utilities meet quotas that require them to mix their purchases of traditional power sources, such as coal, with certain amounts of alternative energy.
So besides selling the biopower itself, producers can peddle a state "renewable energy credit" (REC) for each megawatt hour generated. That and a small federal tax credit are encouraging bigger plants.
Public Service of New Hampshire recently spent $75 million to convert a 50-megawatt coal generator to a similar-size wood-fired plant. But the cost will be more than offset in just a few years by the $15 million a year the company will earn from REC sales to Massachusetts utilities, says generator manager Richard Despins. The unit, which started up last month, also helps meet new state pollution limits and supports timber-industry jobs that will pump $20 million into the local economy, he says.
In South Point, Ohio, Biomass Group plans to start up a 200-megawatt wood-fired plant, the largest ever, in 2009. "We're the only (wood biomass) facility … in a predominantly coal region," says lead investor Mark Harris. That, he says, will allow the company to build a "utility-scale" project that sells power to Eastern states with high electric rates.
Other biomass fuels:
•Municipal solid waste. The nation's 89 waste-to-energy plants produce enough electricity for 2.3 million homes by burning household trash, most of which is organic. About a dozen new facilities are proposed. With Frederick County, Md., paying $57 a ton to send its trash to out-of-state landfills and power prices soaring, building a waste-to-energy plant would save money in just a few years, says Michael Marschner, county utilities director.
•Landfill gas. About 300 U.S. power plants capture methane spewed by a nearby landfill's decaying organic matter and use it as natural-gas-like fuel. That cuts potential methane pollution. With natural gas prices high, Waste Management is building 10 plants a year at its landfills, 76 of which already have generators.
•Animal waste. Anaerobic digesters are oxygen-deprived tanks that break down cow manure into methane that's sent to power plants or pumped through natural-gas pipelines. Environmental Power (EP) operates digesters at three dairies in Wisconsin and plans four more in Texas and six in California. PG&E is set to buy enough gas from EP to power 50,000 homes.
"It really reduces the odor (and methane emissions) of the manure and … it's another income stream," says Lee Jensen, an Elk Mound, Wis., dairy farmer. He and his partners own a digester that generates about $360,000 a year in gas sales to a small utility.
•Agricultural wastes. Fibrowatt is starting up a Benson, Minn., power plant large enough to serve 60,000 homes. It will burn turkey manure, along with sunflower shells, wood shavings and leftover corn stalks. The company will pay just $2 per ton of manure to state turkey growers. By collecting the manure and related materials daily, Fibrowatt says it's helping turkey growers, who otherwise sell the waste to farmers as fertilizer.
Most big utilities haven't built biomass plants due to costs, but some are "co-firing" small amounts of biomass in coal plants. At a Gadsden, Ala., coal plant, switchgrass makes up 5% of Southern Co.'s fuel. The utility is weighing similar setups for eight additional plants.
"We have a lot of growth in the Southeast, and we want to meet that growth in a way … that's environmentally friendly," says Leonard Haynes, who heads the company's renewables program.