Waste to Energy Gasification
Traditional waste-to-energy plants (incinerators) burn trash to create energy.
They create environmental problems including toxic air emissions and waste ash.
No new waste-to-energy plants have been built in the U.S. for over 10 years. 
A newer, more efficient and environmentally friendly technology has been developed, which gasifies the waste before it is burned. Gasification converts organic materials in the trash, under high temperature and pressure, into synthetic gas (syngas), which is used to generate electricity. Syngas is composed of hydrogen, carbon monoxide, and other gases depending on the feedstock and gasifier conditions. Syngas has a heating value that is 2/3 that of natural gas and has similar emissions to natural gas.
Minerals and other impurities that do not gasify are trapped in an inert slag. Sulfur is extracted after being converted to hydrogen sulfide or carbonyl sulfide. Nitrogen oxides do not form in the gasifier (due to a lack of oxygen), instead, ammonia is created and taken out of the gas.
An Integrated Gasification Combined-Cycle (IGCC) system burns the syngas in a combustion turbine which drives an electric generator. Exhaust from the turbine is used to boil water and make steam for a steam turbine generator, increasing the efficiency tremendously. (Photo credit: D'Arcy Norman)
Waste Gasification in Massachusetts
Ze-gen, founded in 2004, develops waste gasification technology which converts construction and demolition waste (C&D) and municipal solid waste (MSW) into near zero-emissions synthetic natural gas (syngas) and electrical energy through combined-cycle power production. They recently opened a demonstration facility in New Bedford, MA.
Ze-gen is focused on delivering “modules” as standard products to the marketplace. Each Ze-gen module will generate 30 megawatt hours of net electrical output through the processing of 450 tons of C&D or MSW per day, with zero emissions.
Sources:
US Department of Energy: How Gasification Works