Trash-Based Biofuels Could Alleviate Land Use, Emissions Issues

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Biofuels are touted as a cleaner alternative to fossil fuels, but they come with their own set of problems. One of the biggest concerns lies in the displacement of food crops like corn, which can raise food prices and have other indirect effects around the world on land use and agriculture.

A new production method could begin to alleviate that problem while solving another: It turns trash into biofuel.

Last week, the Canadian company Enerkem announced a large financial partnership with U.S.-based Waste Management to ramp up Enerkem’s production of biofuels from sorted municipal waste. Enerkem already has two waste-to-biofuel plants operating in Sherbrooke and Westbury, in Quebec, and plans to open new plants in Edmonton and in Mississippi.

“Biofuel feedstocks that we’re using now are not going to cut it in the long run in terms of sustainability,” said Alice McKeown, a research associate at environmental group Worldwatch Institute. “So we’re very supportive of looking at new ideas, investigating new feedstocks, and looking into what really will work, and if it will work.”

Enerkem and similar companies, such as BlueFire Ethanol, turn sorted waste and construction debris first into a synthetic gas, or syngas. The gas is conditioned and treated, and then catalytically converted into ethanol or other biofuels. According to Enerkem, its process can convert one tonne (1.1 tons) of waste into about 95 gallons of cellulosic ethanol. BlueFire Ethanol claims it can produces about 70 gallons from a similar amount of waste.

Land, Climate and Chemicals

Producing energy from waste on a large scale has potential to diminish several of the complaints about biofuels.

“If you plant more corn in this field, is it going to cause a farmer in some other part of the world to cut down a forest to plant some other crop that’s no longer being grown?” McKeown asked. “Those are the indirect land use effects, and those are very hard to quantify.”

Taking waste that would otherwise be destined for a landfill clearly does not involve any competition with food crops like corn or soy.

The other major improvement over first generation biofuels comes in the form of carbon emissions cuts.

According to a 2009 Worldwatch Institute report co-authored by McKeown, corn-based ethanol results in, at best, an 18 percent reduction in lifetime greenhouse gas emissions over gasoline; some researchers have claimed that its net effect can actually be to produce more carbon dioxide than gas. Cellulosic ethanol produced from such things as municipal waste has the potential to reduce emitted CO2 by more than 90 percent over gasoline, according to the Worldwatch report. Keeping waste out of landfills would also reduce methane released into the atmosphere.

In fact, a study published last year in the journal Waste Management and Research indicated that a comprehensive waste management plan including the conversion of waste into energy (both for vehicle fuel as well as electricity generation) could eventually provide a full gigaton reduction in carbon emissions per year if implemented on a large enough scale. That would be significant — according to research compiled by United Nations Environment Program from nine centers, the world needs to cut its emissions by about 15 to 20 gigatons (from a projected total of 62 gigatons under a business-as-usual scenario) by mid-century in order to avoid some catastrophic effects of warming. Notably, though, the journal study was written by researchers at Covanta Energy, a company involved in the waste-to-energy industry.

There are other environmental impacts involved with ethanol production that waste could avoid as well. The chemicals used to treat many crops grown for biofuels have been found to contaminate surrounding environments.

“And those chemical inputs — aside from themselves causing energy use and greenhouse gas pollution — also cause water pollution and a lot of problems with water quality downstream,” McKeown said.

Ethanol Blends

Even if production of cellulosic ethanol from alternative sources like waste ramps up, it doesn’t answer lingering questions involving the technology and infrastructure to actually use that fuel.

In an e-mail to SolveClimate, Brian Jennings, the executive vice president of the American Coalition for Ethanol, agreed that

“It’s widely recognized that additional feedstocks are going to be necessary for biofuels to overcome our nation’s dependence on oil. … But one hurdle standing in the way of commercialization for all of these sources is the federal government’s regulatory cap on blending ethanol.”

The EPA will decide in mid-2010 whether to raise the current cap on blending ethanol with gasoline from 10 percent ethanol up to 15 percent. It is believed that most newer car engines can handle the change, but in December the EPA delayed its decision on the blend change until more testing could be conducted. The U.S. is currently behind schedule in meeting a congressional mandate to produce 36 billion gallons of biofuel a year by 2022, with production now at about 12 billion gallons a year, primarily from corn ethanol. Cellulosic ethanol, which was originally supposed to hit 100 million gallons a year by 2010, is only about 6.5 million gallons now.

When those issues will be sorted out and how quickly cellulosic ethanol production can grow remains to be seen, but for the moment the alternative ethanol sources like municipal waste are clearly getting attention.

In December, the U.S. Department of Energy awarded a $50 million grant to Enerkem — part of a recovery act project providing $564 million for related biorefinery projects — to open a waste-to-biofuel plant at an existing landfill in Pontotoc, Miss. The plant will convert 300 tons of waste per day, producing 10 million gallons of ethanol each year. Bluefire received a grant at the same time for $81 million to build an plant in Fulton, Miss., that converts municipal waste, mill residue and woody biomass to ethanol.


See also:

Algae Emerges as DOE Feedstock of Choice for Biofuel 2.0

EPA Recalculates Land Use Changes, Gives Corn Ethanol Thumbs Up

Fuel-Thirsty U.S. Navy Pledges 50% Cut in Oil Use by 2020, and More


(Photo: D’Arcy Norman/CC BY 2.0)