Learning to Value Refuse
The ethos for dealing with waste has completely changed in recent years, from being a material that presents the problem of how to treat it, to being a resource that has value. _ShorehamHeraldNot long ago, "environmentalists" were wringing their hands from worrying about mountains of disposable diapers in landfills, collapsing around them and smothering them in their sleep. But now, garbage--even plastics--are turning out to be valuable materials, capable of being converted to energy, fuel, chemicals, and other useful products. One approach to the profitable use of waste plastics is gasification.
“It’s complete gasification,” Shea tells Biomass Magazine. “There’s no melting or slagging. The burner takes the granulated plastic, sized in diameter between 2 and 10 millimeters, from a solid to a liquid to a gas immediately in the combustion chamber, Shea explains. “That gas is actually producing the heat we need to transfer into the boiler system.” During the gasification of the granulated waste plastic, temperatures are so high—1,850 degrees Fahrenheit—the studies indicate emissions profiles cleaner than that of natural gas. “It’s amazing,” Shea says. “I’ve run this machine for years—demos and such—and you could stand right next to it and there’s nothing coming out of that barrel but a flame and heat.”Exxon has looked into various methods of small to medium scale gasification of biomass, coal, shale etc. with various collaborating companies--most recently Pratt and Whitney. Bioenergy and energy from waste are receiving a lot of attention from huge multinational oil companies, chemical companies, automobile companies, airlines, forestry and paper industry companies, most governments of developed and emerging countries, and a large range of entrepreneurs and startups.
...While interest in combusting and gasifying plastic appears to be growing, there is another route to making practical use of all the waste plastics modern society produces. Through what it calls catalytic pyrolysis, Polymer Energy LLC, a division of Northern Technologies International Corp., has developed a system to convert waste plastics into liquid hydrocarbons, coke and gas, which can then be used as boiler fuel for power generation. “The technology uses lower temperatures than gasification—significantly lower—so it’s more energy efficient to produce,” says Kathy Radosevich, business development manager with Polymer Energy. Through “random depolymerization,” or selective breaking of carbon-to-carbon bonds, in addition to feeding in proprietary catalytic additives, the reactor melts and vaporizes waste plastic in one step at temperatures between 840 and 1,020 degrees F. The company reports that, on average, 78 percent of every pound of plastic fed into the Polymer Energy system is converted to liquid hydrocarbons, coke and gas. The resultant coke can be further processed to produce additional fuel oil.
Polymer Energy’s catalytic pyrolysis system processes polyolefins like polyethylene and polypropylene with up to 5 percent other plastic materials, plus up to 25 percent additional nonplastic waste, such as paper, glass, sand and water—making it ideal for processing municipal wastes. _biomassmag
More members of the public, who have been largely oblivious to bioenergy as a steadily growing replacement for fossil fuels, are waking up to the nascent bioenergies industry with the potential to become a worldwide giant source of energy.