If waste cannot be re-used or recycled then it should be utilised to provide heating and/or renewable energy. Waste to energy technologies include anaerobic digestion; incineration; use of secondary recovered fuel (an output from mechanical and biological treatment processes); pyrolysis; gasification and plasma arc heating. Currently around 8 per cent of municipal waste is treated by waste to energy facilities but it is estimated this will rise to at least 25 per cent by 2020.
Waste to energy processes involve heating waste under controlled conditions to reduce the amount of waste requiring final disposal to landfill. At the same time energy is recovered to produce heat and power or gas is produced which can be used as fuel. The waste incineration directive requires any heat generated through incineration to be recovered as far as practicable. Towns and cities can meet some of the requirements of the European Landfill Directive by diverting unrecyclable waste to energy production.
These operations will only operate efficiently with good levels of emissions control if they are provided at a municipal scale. The role of waste to energy in powering the communities of the future is potentially significant, particularly as this could present a lower carbon alternative to coal-fired power. However, such facilities would require specific urban design and management responses to accommodate them.
It should be noted that this sustainable environment strategy still has several issues and potential risks that have to be resolved before more cities accept and apply it. Certainly the biggest problem refers to potential health risks emerging as the result of waste to energy processes. Another issue refers to relatively low level of energy efficiency of these processes. This becomes even greater issue considering that waste to energy process doesn’t create renewable energy. Waste incinerations are often seen as financial burden, especially due to relatively small number of required employees. All of these issues are being analyzed in search for effective and applicable solutions.
This section explores some of these issues.