While the world may be running short on certain key resources, including fresh water and rare metals like iridium, one resource is as abundant as ever: trash. The World Bank projects the global municipal waste stream to hit 2.2 billion tons per year by 2025, up from about 1.3 billion tons now.
Conceptualizing trash as a resource may be key to reducing its burden on communities, particularly in developing countries where landfills tend to be located closer to living areas. (In America, landfills are normally placed at the edge of cities and towns). If we can find ways of mining trash for precious commodities or turning it into energy, we could both reduce the size of the piles and create something useful. More to the point, repurposing trash would curb greenhouse gas emissions. Landfills are a significant source of methane, a pollutant many times more harmful to the atmosphere than carbon dioxide.
One useful trash conversion innovation: the FastOx Pathfinder gasifier developed by Sierra Energy, a California startup. It takes any part of the waste stream–household, medical, hazardous–and converts it into carbon monoxide and hydrogen, which can be made into synthetic gas or diesel. The process uses a conventional blast furnace, but instead of adding air, it pipes in pure oxygen and steam to create temperatures over 4,000 degrees Fahrenheit. The oxygen reacts with carbon in the waste to make “synthesis gas” (syngas)–a mix of carbon monoxide and hydrogen. That can be burned to make electricity or create fuels.
The system allows municipalities to make their own energy on-site in small modular units, Mike Hart, CEO of Sierra Energy, tells Co.Exist. The company has set up one demonstration project at the Fort Hunter Liggett U.S. Army training facility in Monterey County, California; it’s looking to develop another project in Mexico City. “We want to put this in slum neighborhood areas where we can reduce waste and help with health hazard issues,” adds Paul Gruber, Sierra Energy’s VP of external partnerships.
Every 25 tons of waste can create 1 megawatt of electricity, Gruber says: enough to power 1,000 average U.S. homes (that number would go up if we curb our wasteful electricity use). The FastOx recently won a $150,000 grant award from the Roddenberry Foundation, set up in memory of Star Trek creator Gene Roddenberry. The money will help develop the project south of the border.
“These slum neighborhoods are really filthy environments,” Gruber says. “Whether you’re living on the landfill or nearby, trash is just everywhere. [With this system], we could power a whole micro-grid, or even a mini city.”