The extremely high temperature of plasma can break the molecular bonds of any garbage in the container, thus transforming organic matter into synthesis gas (a mixture of carbon monoxide and hydrogen), and other substances into slag similar to glass body. Syngas can be used as fuel for turbines to generate electricity, and it can also be used to produce ethanol, methanol and biodiesel. Slag can be processed into building materials.
In the past, the gasification method was difficult to compete with the traditional municipal waste treatment method in cost. However, with the maturity of technology, the cost of this method is reduced and the energy price is rising. Luis Chil, CEO of the Institute of Plasma Research at Georgia Institute of Technology, said that "these two curves have crossed-it is cheaper to send garbage to a plasma treatment plant than to pile it up into a mountain of garbage".
In early summer of 2009, waste management company, a giant in waste treatment industry, began to cooperate with Inetec to put Inetec's plasma gasification equipment into commercial use. They are building large-scale pilot plants in Florida, Louisiana and California, each with a daily garbage disposal capacity of over 65,438+0,000 tons.
Plasma is not perfect. Although the toxic heavy metals contained in glass slag have passed the leachability standard of the US Environmental Protection Agency (Japan and France have used this material as building materials for many years), the community still has doubts about building such a factory. The carbon footprint of synthetic gas power generation is smaller than that of coal-fired power generation. Chilceo said: "Treating 1 ton of garbage with plasma is equivalent to reducing 2 tons of carbon dioxide emitted into the atmosphere." But this method will still increase the net greenhouse gas emissions.
Although things can't be perfect, according to the statistics of the US Environmental Protection Agency, if all urban solid waste in the United States is treated with plasma to generate electricity, it can provide 5% ~ 8% of the total electricity demand in the country-equivalent to the power generation of about 25 nuclear power plants or all hydropower stations at present.
At present, foreign plasma arc garbage melting technology has entered the practical application stage in the fields of melting medical garbage, municipal garbage (the optimal scale of this technology can treat 1000 tons of municipal garbage per day and generate 20 MW of electricity) and burning fly ash. It is estimated that by 2020, the daily output of garbage in the United States will reach 6,543,800 tons. Therefore, it will become more and more important to recover some energy from garbage by plasma technology.