The present stage of development of plasma gasification technology to convert organic waste materials to energy products has exceeded all expectations in terms of efficiency, cost-effectiveness and reduced environmental impacts. Plasma heating systems are about three times hotter than fossil fuel burners. At these temperatures organic compounds are reduced to their elemental constituents, resulting in the formation of a large volume of “synthetic gas (syngas)”, and a small volume of simple acid gases which can be readily neutralized. The syngas could produce significant amounts of net electricity which could be sold to the electrical grid or converted into steam or liquid fuels. The molten slag residue will harden into an inert rock-like material which can be used as construction materials as aggregate or in concrete and asphalt mixtures. More recent studies have indicated that the molten stream can be fed into “spinning machines” which will produce a mineral wool byproduct (“plasma wool”). This material can be used as building insulation and for other high value materials.
The unique benefits of plasma gasification of wastes as compared to other thermal waste-to-energy (WTE) technologies include the following advantages:
Energy Efficiency. One ton of average MSW could create about 815 kWh of electricity to the grid. This is about 20-50% more electricity than any other existing or emerging WTE technology.
Cost Effective. Capital costs of plasma gasification facilities are roughly equivalent to Mass Burn WTE incinerators. However, because of the greater power production capabilities, plasma WTE facilities are far more cost effective to build.
Robust Waste Streams. In addition to MSW, plasma facilities can process industrial wastes, biomass, animal carcasses, coal, scrap tires and many others carbonaceous waste streams. Plasma gasification plants can produce steam, electricity, ethanol, methanol and a large number of other syngas-based fuel products.
Landfills. Plasma gasification of waste materials would reduce or eliminate the need for new landfills, and existing landfills can be mined for energy production.
Cleaner Emissions. Because of the high temperatures, the low volume of gas emissions, and the dissociation of organic compounds, gaseous emissions from plasma waste processes are much cleaner than from conventional gasification or incineration processes.
Greenhouse Gas Reductions. In landfills, MSW produces methane; however, if that MSW was sent to a plasma facility no methane would result. In addition, the power produced could replace the energy made at a coal-fired power plant. Thus, for every ton of MSW sent to a plasma plant for power production, up to two tons of CO2 equivalent emissions could be reduced from the atmosphere.
Recent U.S. Environmental Protection Agency (EPA) studies have also supported plasma gasification and other WTE technologies, as follows:
• WTE power plants produce electricity with less environmental impact than almost any other source of electricity.
• MSW is the only important and stable WTE materials stream, capable of producing up to 4% of the U.S. electricity demand. At this rate, MSW could produce an amount of electricity equal to 20 nuclear power plants. (Other studies have concluded that global wastes could produce up to 10% of the worldwide electricity demand)
• Waste-to-Energy is much preferred over landfilling wastes.
Four commercial WTE plants have been built in Japan and India since 2002. Several more plants are under development in the U.S., Canada and Europe at the present time. It is anticipated that at least two of these plasma facilities will begin construction within the next year.
In summary, the full implementation of plasma gasification of MSW holds the promise to significantly:
• Reduce the MSW disposal problem;
• Alleviate the energy crisis around the world;
• Eliminate the need for landfills.