Cascade utilization of biomass: strategies for a more efficient use of a scarce resource

Abstract

The utilization of biomass is an important driving force for the socio-economic appropriation of net primary production (NPP) and thus leads to major disturbances in the natural energy flow of ecosystems. The appropriation of aboveground NPP in Austria amounts from 50 to 51% which is higher than the estimates for global NPP appropriation (25–39%). NPP appropriation is associated with a reduction of the standing crop of ecosystems. It leads to a disturbance of biogeochemical flows (e.g. carbon and nitrogen flows). NPP appropriation could also contribute to biodiversity reduction. These potentially detrimental side-effects can be reduced by increasing the efficiency of biomass use by implementing the strategy of ‘cascade utilization’. This strategy proposes optimizing the use of biomass as a raw material and as an energy carrier in an integrated manner. If biomass, that had been previously used for some other purpose, is used for energy generation, it will not contribute to NPP appropriation. The utilization of currently unused biomass residues for energy generation could contribute some 76 PJ in Austria, i.e. 6% of the current primary energy consumption, without increasing NPP appropriation.