Die Ökobilanz der energetischen Holzverwertung: Faktoren für einen hohen ökologischen Nutzen

Abstract

Wood energy is increasingly used to replace non-renewable energy sources. Energy wood is a limited resource and should therefore be used wisely not only to maximize the economic but also the environmental benefits associated with its use. This article assesses the environmental burdens associated with wood energy (for heat, electricity and transportation) and the benefits that may arise when non-renewable energy technologies are substituted. It is shown that from a global warming perspective the use of wood energy seems almost always beneficial, but this effect may be significantly reduced if biogenic CO 2 is taken into account. The method of ecological scarcity on the other hand, which considers several additional environmental dimensions and combines these into a single score, shows significantly lower environmental benefits of wood in comparison with non-renewable energy. One of the principal reasons for this are air emissions associated with wood energy such as particulate matter, nitrogen oxides (NOx) and volatile organic carbon (VOC). Considerable environmental benefits can be achieved in both cases if the following three key factors are respected: 1) a wise choice of the substituted technology and the underlying energy carrier, 2) a high efficiency in the conversion from energy contained in biomass to final energy, and 3) the implementation of measures to reduce air emissions such as particle filters and, if possible, more advanced flue gas cleaning. The article then discusses the limits of the comparison and selected issues within the life cycle assessment methodology that need further development.