http://www.txchnologist.com/2012/plasmas-trash-to-energy-promise-faces-big-hurdles

THE CITY OF THE FUTURE

THE URBAN LANDSCAPE IS CHANGING, BUT INTO WHAT?

Urban centers have a big trash problem coming down the chute. According to a report published this month by the World Bank, we will be producing 2.2 billion tons of garbage globally every year by 2025. Not only will there be more people, but each one of them will be churning out more waste—at least three pounds per person.

“It’s growing by leaps and bounds,” says Dan Hoornweg, a World Bank urban specialist who coauthored the report.

Plasma fixes all…

The world’s expanding waste problem is causing many to look for a solution in new technologies. One in particular, plasma gasification, has been getting more attention recently because it offers to turn that refuse into clean energy. The innovation is a waste-processing technique that obliterates trash with a plasma torch and leaves two byproducts, a glassy solid and a mix of combustible gases.

Japan has been operating waste-to-fuel gasification plants since the turn of the century and Canada recently began delivering power to homes in Ottawa with a similar plant. U.S. waste management and energy authorities remain curious but hesitant. And no one seems to want to be the first to try it out. As proposals emerge and die, advocates have lined up for and against plasma gasification. Some see a win-win scenario of reduced waste and energy self-sufficiency. Others consider the technology to be an experimental distraction from the tenets of sound waste-management policy.

In 2010, Dovetail Partners, a non-profit corporation that advises companies and governments on environmental decisions, wrote up a report about plasma gasification for the city of Palisades, MN. City officials were interested in opening a plant, but wanted more information about the technology’s track record and environmental impact. Dovetail concluded that when operating correctly, a plasma gasification plant is a closed system.

In that system, preferably sorted trash enters the machine. It gets hit with an arc of ionized gas that reaches temperatures above 15,000 degrees Fahrenheit, hot enough to immediately convert all of the organic material into carbon monoxide, carbon dioxide and hydrogen. The ash remnants fall to the ground and, when treated with water, solidify into a glassy lump.

Both products can be reused—the gases can be burnt as fuel and the solids can be ground up and made into pavement. Theoretically, everything gets captured during the process and no toxic materials leak out of the plant.

…Or does it?

This isn’t always the case. When looking at the track records of the few existing plants around the world, Dovetail found that some nasty things do escape—hydrochloric acid, particulate matter and dioxins. But none of the emissions were above the maximum level set by the U.S. Environmental Protection Agency.

Advocacy groups like the Global Alliance for Incinerator Alternatives have cited other studies about emission rates, but Jim Bowyer, a Dovetail Partners researcher, says these reports mix numbers from plasma gasification with those from other plants. “There are high-temperature incinerator units and then there are plasma, and one shouldn’t be confused with the other,” he says. “We found in every single case that the problems that have occurred have been in high-temperature incinerators.”

But there’s a larger problem with moving to any incineration technologies, which is that they encourage a move away from recycling. For a plasma gasification plant to operate most efficiently, trash would be separated first, removing metals and other materials that yield a higher profit when recycled and leaving only the organic garbage. But not everyone thinks this is what would happen.

“In the world of academia, you could envision these things developing simultaneously. In the real world, government doesn’t work that way,” says Eric Goldstein, director of New York City environment at the Natural Resources Defense Council.

To recycle or dematerialize

He would prefer to see governments pushing policies like curbside recycling and economic reuse incentives before we start obliterating our trash. “The concept is, let’s do everything we can to advance recycling first before moving to these new, largely unproven technologies,” he says.

Even if gasification plants can make our garbage disappear, they may also lure us into complacency. Watching a landfill get bigger and bigger at least encourages people to waste less. But having a black hole that we can throw our trash into and then forget about it could do the opposite, especially when it’s supplying power to our homes.

“If you have an incinerator, there’s an inherent incentive to feed that thing as much as possible,” explains The World Bank’s Hoornweg. “It’s not usually conducive to waste minimization, and waste minimization is the thing we should be asking for.”

For now the question is moot—building gasification units is very expensive. It only makes sense for companies if they know the fuel they get out of it will cover part of the cost and, so far, that equation has not played in the industry’s favor. In 2006, Saint Lucie County, FL, began planning to partner with energy provider Geoplasma to build a plasma gasification plant for the region. Last month, they ditched the proposal. County Commissioner Chris Craft blames the economy. “By the time we were finishing putting together the negotiation of the contract and the air quality permit, which takes a few months or so, the economy had collapsed,” he says.

Such obstacles surely won’t close the book on plasma gasification, Bowyer says. “Going forward, as waste becomes more and more of an issue in high-population areas, then gasification is going to be looked at more closely and it’s going to get more and more interesting.”