Environmental compatibility of renewable energy plants

摘要

In Italy and many European countries energy production from biomass is encouraged by strong economic subsidies so that biomass energy plants are getting large diffusion. Nevertheless, it is necessary to define the environmental compatibility as well as technological and economic issues dealing with the emerging renewable energy scenario. This evaluation should take into account global parameters as well as environmental impacts at regional and local scale coming from new polluting emissions. The environmental balances regarding new energy plants are of primary importance within very polluted areas such as Northern Italy where air quality limits are systematically exceeded, in particular for PM_(10), NO_2 and ozone. The paper analyses the energetic and environmental performances of renewable energy plants and compares them with traditional fossil fuel energy plants. The study is focused on the anaerobic co-digestion of manure and energy crops and the combustion of poultry manure, with reference to ammonia, CH_4 and N_2O releases, as well as NOx from the energetic section. The most important conclusion that can be drawn is that the production of renewable energy from anaerobic digestion, can strongly increase ammonia and NOx emissions and, in some cases, also GHG emissions could be worrying, whereas the application of best available techniques to waste gas cleaning and energy recovery allows positive emissive balances.