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

The utilization of biomass is an important driving force for the socio-econ omic 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 asso ciated with a reduction of the standing crop of ecosystems. It leads to a d isturbance of biogeochemical flows (e.g. carbon and nitrogen flows). NPP ap propriation could also contribute to biodiversity reduction. These potentia lly detrimental side-effects can be reduced by increasing the efficiency of biomass use by implementing the strategy of 'cascade utilization'. This st rategy proposes optimizing the use of biomass as a raw material and as an e nergy carrier in an integrated manner. If biomass, that had been previously used for some other purpose, is used for energy generation, it will not co ntribute 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 appro priation. (C) 2000 Elsevier Science B.V. All rights reserved.