Solid biofuels: environmental concern and integrated analysis of energy sustainability

A co-generative plant situated in Northern Italy (CPN) was used to test an approach for evaluating the environmental pros and contras of using wood chips of different origin as biofuel. The EROI (Energy Return On Energy Investment) of the plant was also assessed. Used woodchips were of the two main categories and were obtained from i) natural ligneous trees from energy crops and ii) uncontaminated ligneous biomasses from agriculture and forestry wastes. Woodchips were characterized by determining the relevant physical and chemical properties for the plant functioning. Biofuels used in CPN have different physical properties and this may be the reason explaining a lower performance of some features (LHV and bulk density) of the wood chips from energy crops compared to agriculture and forestry recovery materials. Although recovered material contained higher Cl, S and heavy metal levels than wood chips from energy crops, but LHV (Low Heating Value) and lower price of recovery materials suggested that this one could be a good alternative source of energy especially in developing countries. This observation demands frequent integrity checks of the pollutants in order to guarantee a low level of environmental risks. This results obtained enable a comparison between the different kinds of materials used and an energy analysis to assess sustainability in the studied territory.