If Rod Bryden has his way, plasma gasification will one day be the way all municipalities dispose of their solid waste.
That day may be far away, especially when most municipal waste managers have little idea what plasma gasification even is. But Bryden, president and chief executive officer of Ottawa, Canada-based Plasco Energy Group, says that the benefits of the technology – plasma gasification generates zero waste, and produces steam that can be used to create on-site electricity – are so many that municipalities will practically be forced to investigate it as they learn more about it.
“This technology is quiet. It produces no emissions and no odors. It delivers power right to the distribution portion of the electrical service system. That helps offload some of the burden on the heavily used public grid,” Bryden said. “All these factors make the ability to convert waste into energy without any emissions a very exciting proposition.”
The plasma gasification process is still in its earliest, most experimental stages. But companies such as Plasco and Tallahassee, Florida-based Renewable Fuels of Tallahassee are attracting attention from municipalities dotting North America and the globe.
So far, the only plasma-gasification plants currently operating in North America are test facilities designed to explore and weed out any bugs in the technology. But proponents of the technology are confident that this will soon change. Plasco, for example, is scheduled to build a plasma-gasification plant in Red Deer, Canada, that will take in 300 tons of municipal solid waste a day. It has also signed an agreement to build a second plant in Ottawa that will handle 400 tons of waste every day.
Renewable Fuels has been busy, too. The Florida company has signed an agreement to build a plasma-gasification plant in Tallahassee that will each day convert 1,000 tons of mostly municipal solid waste into energy. The plant, as in Plasco’s case, will then sell the energy this process generates back to the city.
“We think that after this project, and after others like this come to fruition and are operating, we’ll see more and more communities adopting this technology,” said Dick Basford, president of Renewable Fuels of Tallahassee. “The economics are now beginning to become more realistic for plasma gasification.”
How it Works
Plasco’s Conversion System facilities can convert municipal household, commercial or industrial waste into green power. The facilities themselves then actually produce revenue by selling the green electricity they generate during the plasma gasification process.
The gasification process actually begins at the collection level, where municipal employees remove any waste materials with high reclamation value from the waste stream. They collect these materials, usually, for recycling purposes.
Once workers remove these more valuable products from it, the municipal solid waste stream is sent through shredding equipment. The stream then enters the plasma gasification conversion chamber, which, using recycled heat, converts the waste into a crude gas, better known as syngas.
The syngas then flows to a refinement chamber where plasma torches refine the gas into a cleaner version of syngas. Plasco officials call this type of gas PlascoSyngas.
The process doesn’t end here, though. The PlascoSyngas moves through a Gas Quality Control Suite, which recovers sulfur, removes acid gases and segregates heavy metals found in the waste stream. This leaves behind a clean PlascoSyngas. Best of all, the gas is created without generating any air emissions.
Creating Onsite Power
The clean syngas is used to fuel internal combustion engines that generate electricity. The waste heat these engines generate is combined with waste heat recovered from cooling the PlascoSyngas in a Heat Recovery Steam Generation unit to produce usable steam. This steam can be used for a variety of purposes: The plasma gasification facilities can use it to generate additional electricity through a turbine or they can use it for industrial processes or district heating.
There is no waste from this process. The solid residue that does form in the gasification facility’s conversion chamber isn’t even wasted. Instead, workers send this residue to a high-temperature carbon recovery vessel also equipped with a high-temperature plasma torch. The torch melts the solids and converts any remaining volatile compounds and fixed carbon into crude syngas.
The new crude syngas is eventually fed back into the conversion chamber, while the remaining solids are melted into a liquid slag and cooled into small pellets. These pellets can then be sold as construction aggregate.
The benefit of the plasma gasification process is that it creates no waste and generates energy while helping municipalities dispose of solid waste. The people promoting the technology hope that these benefits will cause more municipalities to look at gasification as an alternative to landfills.
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