Web Exclusives | Energy & Sustainability
Garbage in, Energy out: Turning Trash into Biofuel
Making biofuels from waste makes dollars--and sense
| August 10, 2011 | 1
Image: Photograph by Levi Brown
OverviewThe False Promise of Biofuels
OverviewIntoxicated on Independence: Is Domestically Produced Ethanol Worth the Cost?Edmonton is Canada's chief oil city as well as the capital of Alberta, the province that hosts the bulk of the country's tar sands. Given the expense of converting this mix of dirt and heavy oils to more usable petroleum products, the province is not keen on alternative fuels. Nevertheless, in 2012 Edmonton will host a chemical plant owned byEnerkem that will turn garbage into 36 million liters of ethanol and methanol per year.
"Waste as a feedstock [for biofuels] has a number of advantages," says Enerkem's co-founder and chief technology officer Esteban Chornet, a former engineer at the U.S. National Renewable Energy Laboratory. "It is logistically available and it is low in value, if not negative in value."
Turning garbage into fuel is potentially an answer to two pressing problems—diminishing the world's dependence on fossil fuels and an alternative to burying trash in landfills. In fact, the 468 million metric tons of trash produced in North America each year could provide 47 billion liters of ethanol—or roughly the same amount as produced from corn, which presently supplies 10 percent of U.S. gasoline demand.
Enerkem takes the "fluff" of municipal solid waste—the plastics, textiles and wood that isn't recycled or the leftovers of agriculture or forestry—gasifies it and, using catalysts and water, transforms the gas via multiple chemical steps into ethanol or other products. Other companies, such as Wheelabrator, simply fortify the gas and burn it directly to produce electricity—although that can result in the emissions of toxic chemicals, such as dioxins—or employ additional complex chemical steps. For example, Range Fuels in Georgia similarly attempted to gasify waste from the pulp and paper industry and transform it into ethanol directly but foundered in perfecting its catalysts. "Nature has not given us that selectivity to shift syngas to ethanol," notes chemical engineer Chornet, who started Enerkem in 2000 to make fuel from forestry residues, inspired by his father on Spain's island of Majorca, who made electricity by burning wood waste from his sawmill in the 1930s.
"Waste as a feedstock [for biofuels] has a number of advantages," says Enerkem's co-founder and chief technology officer Esteban Chornet, a former engineer at the U.S. National Renewable Energy Laboratory. "It is logistically available and it is low in value, if not negative in value."
Turning garbage into fuel is potentially an answer to two pressing problems—diminishing the world's dependence on fossil fuels and an alternative to burying trash in landfills. In fact, the 468 million metric tons of trash produced in North America each year could provide 47 billion liters of ethanol—or roughly the same amount as produced from corn, which presently supplies 10 percent of U.S. gasoline demand.
Enerkem takes the "fluff" of municipal solid waste—the plastics, textiles and wood that isn't recycled or the leftovers of agriculture or forestry—gasifies it and, using catalysts and water, transforms the gas via multiple chemical steps into ethanol or other products. Other companies, such as Wheelabrator, simply fortify the gas and burn it directly to produce electricity—although that can result in the emissions of toxic chemicals, such as dioxins—or employ additional complex chemical steps. For example, Range Fuels in Georgia similarly attempted to gasify waste from the pulp and paper industry and transform it into ethanol directly but foundered in perfecting its catalysts. "Nature has not given us that selectivity to shift syngas to ethanol," notes chemical engineer Chornet, who started Enerkem in 2000 to make fuel from forestry residues, inspired by his father on Spain's island of Majorca, who made electricity by burning wood waste from his sawmill in the 1930s.
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