There are a variety of ways that waste can be converted into electricity; whether its food scraps, landfill debris, or municipal solid waste, there is always a way to squeeze some watts out of waste. Anaerobic digesters use microbes to turn yesterday’s sandwich into energy-rich methane, while incinerators burn up trash to produce gases for heat and electricity. And landfills across the country pipe fresh methane from decomposing organic waste into natural gas facilities.
All of these processes provide a suitable alternative to simply burying the trash in a landfill. But none of them are a suitable solution for converting all types of waste into energy. That’s where plasma gasification stands out.
Plasma gasification is the process of using plasma (the same form of matter that comprises the sun) to turn organic matter into synthetic gas and everything else into recyclable metals and glass rock. Unlike incineration, the process doesn’t burn the trash so much as it disintegrates it, destroying the chemical bonds that holds the trash together, turning it into gas. Heavier elements, such as metals, are melted down and collected at the bottom of the gasification chamber forming what is called “slag”. A layer of silica forms on top of the molten slag as a result of glass products, such as bottles, and can be reused in various construction applications.
The plasma itself is generated by two graphite electrodes that produce an arc of electricity between themselves and the molten slag. When the arc is made it super-heats the gases inside the chamber, providing the plasma needed to heat up the chamber. The temperature of the arc can range from 4,000 to 25,000 degrees Fahrenheit, with ambient temperatures inside the chamber reaching as high as 9,000 degrees.
Currently, there are a handful of facilities across the the world that utilize gasification. One of them is located at Hurlburt Air Force Base in Florida’s panhandle, located east of Pensacola. The system uses an industrial shredder to reduce the base’s trash to pieces that are less than two inches in size. All of it is fed into a gasification chamber where everything from tissues to aluminum cases are reduced to either gas or slag. The slag produced by the system is recycled into steel and other metal materials for use by the Air Force. All of the organic gases produced by the chamber are cooled to create synthetic gas. This gas is composed of hydrogen and carbon monoxide, which can be combusted to produce electricity.
The Air Force’s gasification setup can convert roughly 10 tons of trash into 350 kilowatts of electricity, enough to sustain operation of the system itself. The process has been of interest to many in the waste management industry, but has allows flouted investors because of high operational costs and inefficient designs. But thanks to improvements in techniques the technology has gained significant backing from companies such as Waste Management, which is looking to create some of their plasma gasification facilities.
Unlike traditional incinerators, plasma gasification plants produce far fewer toxins and produce zero greenhouse gases. They can also treat medical waste and hazardous materials, two types of debris that run up large disposal fees. Combine that with the ability to recycle metal and glass substances and gasification becomes a highly intriguing method of waste removal.