Life cycle assessment of energy from solid waste-part 1: general methodology and results

The overall goal of the present study is to evaluate different strategies for treatment of solid waste in Sweden based on a life cycle perspective. Important goals are to identify advantages and disadvantages of different methods for treatment of solid waste, and to identify critical factors in the systems, including the background systems, which may significantly influence the results. Included in the study are landfilling, incineration, recycling, digestion and composting. The waste fractions considered are the combustible and recyclable or compostable fractions of municipal solid waste. The methodology used is life cycle assessment (LCA). The results can be used for policy decisions as well as strategic decisions on waste management systems. A waste hierarchy suggesting the environmental preference of recycling over incineration over landfilling is often put forward and used in waste policy making. LCAs can be used to test the waste hierarchy and identify situations where the hierarchy is not valid. Our results indicate that the waste hierarchy is valid as a rule of thumb. The results also suggest that a policy promoting recycling of paper and plastic materials, preferably combined with policies promoting the use of plastics replacing plastics made from virgin materials, leads to decreased use of total energy and emissions of gases contributing to global warming. If the waste can replace oil or coal as energy sources, and neither biofuels nor natural gas are alternatives, a policy promoting incineration of paper materials may be successful in reducing emissions of greenhouse gases.