Update: Converting Plastics to Energy Could Boost US Reserves

Although plastics make up only about 11% of all US municipal solid waste (MSW), many are actually more energy dense than coal. That means a lot of energy isn't being harvested from the more than 80% of already used material that goes to the landfill. Converting these non-recycled plastics (NRPs) into energy with existing technologies could reduce US coal consumption, as well as boost domestic energy reserves, says a new study by the Earth Engineering Center (EEC) of Columbia University. Of course, it would also reduce the carbon footprint of US waste management efforts.

Sponsored by the American Chemistry Council, the 2014 study updates an earlier one on the same topic we told you about back in 2011. The current report found that both recycling and energy recovery from all MSW increased between 2008 and 2011. During that time the recovery rate of plastics, including both recycling and energy recovery, grew from 14.3% to 17.3%. The study used 2011 data on waste management statistics from a Columbia University survey, plus studies conducted in several states characterizing MSW.

The study's authors say that, if all NRPs in the US were converted into energy using modern plastics-to-oil facilities, they could produce enough gasoline to fuel nearly 9 million cars each year. There are several technologies for converting plastics to energy, such as mass burn, refuse-derived fuel, solid recovered fuel, gasification, and pyrolysis. We've told you about gasification and about plastics-to-oil. We've also given overviews of fuel recovery technologies for plastics and other waste here and here.

If all MSW, including plastics, that was sent to landfills in 2011 was converted to fuel using waste-to-energy (WTE) power plants, it would generate enough electricity to power 13.8 million US households, say the study's authors. That's about 12% of the current total number of homes. An additional 9.8 million homes could be heated just from the steam turbine exhaust of those WTE plants. That's already a practice in some northern European countries, such as Denmark.

Converting all that waste to energy would also reduce landfill land use by 6,100 acres, about the size of 4,600 US football fields, as well as reduce greenhouse gas emissions equivalent to those from 23 million cars. If all the NRPs alone were source-separated and converted to crude oil or other types of fuel oil via pyrolysis, that would result in 136 million barrels of oil per year. Alternately, those diverted and converted plastics could produce enough electrical power each year for 5.7 million homes when used as fuel in dedicated power plants.

Some states already do a good job of diverting plastics from landfills by combining WTE conversion with recycling, the study's authors conclude. Those states include Connecticut, Maine, Massachusetts, Minnesota, and New Hampshire.

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