The system involves sorted carbon waste, including plastics, paper, cardboard, food and other plant material, entering a plasma gasification chamber and being turned into syngas by the application of very high temperatures (+6000°C). This process has advantages over incineration, which has not been adopted on a large scale for the conversion of MSW into power because of the low efficiency, fears over emissions and waste from incineration or from existing gasification systems. Compared to incineration systems the Waste2tricity system produces fewer pollutant gases, tar, ash and fly ash and the main by-product, vitrified slag, is inert and can be used as road-building aggregates, with the added benefit of reducing demand for gravel extraction.
Waste2Tricity will develop the process in two stages. In Stage 1 the cleaned syngas will be fed into an internal combustion engine (ICE) generator, with an average generation efficiency of about 30%. In Stage 2, the syngas will be processed and converted to hydrogen and the ICEs will be replaced by new generation alkaline fuel cells, which have the highest conversion efficiency of hydrogen to electricity of any process. By the combination of plasma gasification with fuel cells Waste2tricity claims the net output of electricity to the UK National Grid could increase by over 50% compared to existing technologies and that the new generation fuel cells will increase the net output of electricity by a minimum of 60% over an internal combustion engine generation system or by 130% over a steam turbine system. Waste2Tricity also estimates that the cost of generating electricity can be less than UKP3p (USD$0.04cents) per KWh at today's prices.
This is a very impressive system that will go a long way to improving the environment as facilities could be built directly on landfills thereby utilizing existing roads and saving valuable land. Also, not only will this help reduce landfills and probably the need for them altogether, but the main by-product, inert vitrified slag can be used as a very durable road building aggregate. I am very pleased with the pace at which the British are going in trying to solve environmental problems. I wrote an article last month on CO2 absorbent cement developed by some British scientists and now this "waste2ricity" system is just another reminder to the rest of us in the United States how far we seem to lag when it comes to finding new technologies to clean up the environment and yet we produce most of the world's pollution.
Image obtained from: www.gizmag.com