There’s a good amount of energy tied up in people’s trash cans. But does it make sense to burn it?
I took a tour of Covanta Energy’s waste-to-energy site here yesterday to delve a little deeper into that question. I learned that modern plants like this one are far less polluting than they used to be and that “reduce, reuse, recycle” is clearly the preferred route. For what’s left over after recyling, though, waste-to-energy plants can fill a role as an alternative to landfills, assuming air quality standards remain in force.
This facility north of Boston takes in about 600,000 tons a year of municipal solid waste from nearby Massachusetts and New Hampshire communities. From that “feedstock,” it generates about 40 megawatts of continuous power, or enough to power about 40,000 homes.
The plant uses the same basic process that fossil fuel plants use: heat from combustion creates steam. That steam is pushed through a turbine to turn a generator which produces electricity. Covanta Energy, one of the largest U.S.-based waste-to-energy developers, has developed a few techniques to reduce air pollutants, making them substantially cleaner than 1980s-era incinerators.
The Covanta plant here is able to get 80 percent to 85 percent below EPA air quality limits and reduce the volume of trash by at least 80 percent, according to facility manager Joe Becker.
“One of the problems we are still fighting is that incinerator word. In the old days, incinerators were just a step up from burning things in your backyard. There was no recovery of energy at all. There was no recovery of pollutants at all,” he said.
Source: CNET
By Martin LaMonica