Waste to Energy Conversion
Burning municipal solid waste to generate energy is an alternative way to treat post-recycling waste; this process is performed in Waste to Energy (WTE) plants.
Professor Nickolas Themelis is the Director of the Waste to Energy Research and Technology Council (WTERT): he explained the WTE process in more detail to Decoded Science: “With WTE, hazardous and non-usable organic materials are burnt at temperatures of 800-1000 oC, generating heat and electricity. Compared to landfilling, WTE requires a greater initial investment and is, therefore, more expensive in the short term. There are, however, substantial long-term benefits.
Further to the energy generation, we also reduce the volume of MSW needing landfill; moreover, we can recover metals or other valuable elements present in the waste.”
Indeed, many countries have begun to see the potential of WTE technology; since the beginning of the 21st century, globally there have been more than 120 new WTE plants. Countries like China, for instance, almost trebled their number of plants in the last 10 years.
Burning Waste: Dangerous Emissions?
Although WTE presents several advantages, some people are not very enthusiastic about it. There have been always concerns regarding the possible emissions of hazardous compounds, such as dioxins. These are very toxic molecules, which can be formed during the combustion, if chlorine-containing molecules are burnt.
According to Professor Themelis, this does not happen if appropriate safety procedures are implemented. He tells us that, “The plants have to be built and be operated properly, with systems to clean the gases before the emission in the atmosphere. Both EU and US legislation impose very strict criteria for this; if the criteria are followed, the amount of dioxins released into the atmosphere is well below the legal limits, and does not pose a threat to the environment. To give some figures, the average value measured for 125 WTE plants in France was 0.02 nanograms/m3, while the EU limit value is 0.10 ng/m3.”
Waste Management: Very Important Issue
For Professor Themelis, sustainable waste management is a key issue we should deal with, without any further delays. He says, “Waste management already caused problems in some cities, such as Athens, Naples, Beijing; if we do not do something to deal with it, there will be more and more problems in the future.
For WTE, the contribution of universities and research is essential, to find new and more efficient solutions. The WTERT organization tries to show to waste management industries how research can help in getting better results; we also try to make the public and the policy makers more aware of the problems and of the possible solutions.”
WTERT works in cooperation with Columbia University of New York, and with sister organizations in 12 nations all over the world.
Themelis N.J. et al. Methane generation in landfill. (2007). Renewable Energy, 32, 1243-1257. Accessed September 14, 2012.
Environmental Protection Agency. Dioxins and Furans. (2012). Accessed September 14, 2012.
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