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Got garbage? Need energy?

The idea of turning municipal trash into useful energy has been around for decades, focused largely on generating power from the tossed out wood, mattresses, clothes and food waste that would otherwise go to landfill. The first two commercial energy-from-waste facilities in the United States were built in Iowa and Massachusetts in 1975, sparking a trend that would see nearly 200 facilities built and operating by 1990.

Then the industry got burned. New landfills during the 1990s made it difficult for incinerators to compete, while growing concerns over emissions led to stricter environmental standards and more hostile communities. There are now fewer than 90 facilities, which convert about 13 percent of the nation's municipal solid waste into electricity and industrial steam, according to the U.S. Environmental Protection Agency.

Greener technologies, such as gasification, have brought electricity-from-waste back into the spotlight. Higher electricity prices and landfill tipping fees have once again made such proposals economical. But this time they are competing against another form of energy: ethanol.

Government support for biofuel production, rising concern over the use of corn as an ethanol feedstock and advances in cellulosic-ethanol research have cast municipal garbage in a new light. Many cities and towns, most of them struggling to come up with economical and climate-friendly alternatives to landfills, are trying to decide whether their solid waste should end up feeding the grid or filling up cars.

If announcements from the past month are any indication, the ethanol option is gaining ground.

Fulcrum BioEnergy said last week it plans to begin construction later this year on a $120 million facility near Reno, Nev., that will turn 90,000 tons of garbage from households and businesses into ethanol every year (see Fulcrum BioEnergy Turns Trash Into Treasure).

Just three weeks earlier, Canada's largest ethanol producer, Greenfield Ethanol, announced a joint venture that will see an ethanol-from-waste plant built in Edmonton, Alberta, that process 100,000 tons of municipal trash annually. Both Fulcrum and Greenfield said their facilities are expected to be operational in 2010.

Meanwhile, Range Fuels is building a cellulosic-ethanol plant in Georgia that will use woody biomass from nearby forests, and BlueFire Ethanol aims to construct a facility in Lancaster, Calif., that will use wood chips, grass cuttings and other organic wastes being dumped in a nearby landfill (see Bluefire to Break Ground and The Week: Plugging Into Renewable Energy).

"What we're seeing here is definitely a trend toward municipalities and companies looking into alternative processes to use waste for chemical synthesis into fuels," said Marco Castaldi, a chemical engineering professor at Columbia University who specializes in technologies that make energy from waste.

"What we haven't seen is plants being built with track records that have been successful. The jury is out against how successful it will be against electrical generation."

That hasn't stopped municipalities from calling, said Vincent Chornet, CEO of Montreal-based Enerkem, which is Greenfield's joint-venture partner in the Edmonton project. Enerkem has developed a thermo-chemical gasification process that turns municipal waste into synthetic gas, called syngas. It then uses a proprietary catalytic technique to convert the gas into ethanol.

"We're in advanced negotiations with a number of municipalities," said Chornet, adding that the next commercial project, involving another Canadian city, will likely be announced as early as this fall.

Chornet has crunched the numbers and found that burning syngas to produce electrons makes no economic sense. He said an ethanol facility, based on current electricity and ethanol prices, can make three times more revenue per ton of processed waste compared to a plant that burns its syngas to produce electricity. Enerkem's process, he added, is profitable with oil at $50 a barrel combined with a competitive so-called tipping fee to take the garbage.

"Ethanol is slightly more capital intensive and also operating costs are higher, but not significantly more," said Chornet. "If we simply burn off the syngas for steam and electricity production, what do we do that is so different than incineration? This is not developing the true potential of gasification."

In the words of Don Pierce, president of Greenfield's advanced biofuels group, "Just burning it to make electricity is Neanderthal. There's not a lot of thought going into it." Emissions from simply burning syngas for electricity can also be high if the gas isn't properly cleaned, adding even more cost to the process.