Open Access

Im Herbst 2001 veröffentlichte Bundeswirtschaftsminister Werner Müller einen viel diskutierten Energiebericht. Neben einer Bestandsaufnahme der deutschen Energie- und Klimapolitik befasst er sich auch mit einer Analyse der zukünftigen Entwicklungsmöglichkeiten des Energiesystems. Dabei steht die Frage im Vordergrund, ob und wenn ja, zu welchem Preis eine über das bisher von der Bundesregierung beschlossene Maß hinausgehende Minderung der CO2-Emissionen möglich ist. Referenzpunkt ist das Ziel, im Jahr 2020 eine CO2-Reduktion von 40 Prozent gegenüber dem Niveau des Jahres 1990 zu erreichen. In seinen Zukunftsaussagen basiert der Energiebericht im Wesentlichen auf einer Untersuchung von Prognos/EWI/Bremer Energieinstitut aus dem Frühjahr 2001. Der Energiebericht will mit dieser Zukunftsbetrachtung einen Beitrag zum energiepolitischen Diskurs leisten und eine intensive Diskussion entfachen. Das Wuppertal Institut stellt sich dieser Aufforderung mit vorliegender Antwort. Dabei sollen die Aussagen und Schlussfolgerungen des Energieberichts kritisch hinterfragt und eigenen Überlegungen gegenübergestellt werden.

Contemporary combined heat and power (CHP) systems are often based on fossil fuels, such as natural gas or heating oil. Thereby, small-scale cogeneration systems are intended to replace or complement traditional heating equipment in residential buildings. In addition to space heating or domestic hot water supply, electricity is generated for the own consumption of the building or to be sold to the electric power grid. The adaptation of CHP-systems to renewable energy sources, such as solid biomass applications is challenging, because of feedstock composition and heat integration. Nevertheless, in particular smallscale CHP technologies based on biomass gasification and solid oxide fuel cells (SOFCs) offer significant potentials, also regarding important co-benefits, such as security of energy supply as well as emission reductions in terms of greenhouse gases or air pollutants. Besides emission or air quality regulations, the development of CHP technologies for clean on-site small-scale power generation is also strongly incentivised by energy efficiency policies for residential appliances, such as e.g. Ecodesign and Energy Labelling in the European Union (EU). Furthermore, solid residual biomass as renewable local energy source is best suited for decentralised operations such as micro-grids, also to reduce long-haul fuel transports. By this means such distributed energy resource technology can become an essential part of a forward-looking strategy for net zero energy or even smart plus energy buildings. In this context, this paper presents preliminary impact assessment results and most recent environmental considerations from the EU Horizon 2020 project "FlexiFuel-SOFC" (Grant Agreement no. 641229), which aims at the development of a novel CHP system, consisting of a fuel flexible smallscale fixed-bed updraft gasifier technology, a compact gas cleaning concept and an SOFC for electricity generation. Besides sole system efficiencies, in particular resource and emission aspects of solid fuel combustion and net electricity effects need to be considered. The latter means that vastly less emission intensive gasifier-fuel cell CHP technologies cause significant less fuel related emissions than traditional heating systems, an effect which is further strengthened by avoided emissions from more emission intensive traditional grid electricity generation. As promising result, operation "net" emissions of such on-site generation installations may be virtually zero or even negative. Additionally, this paper scopes central regulatory instruments for small-scale CHP systems in the EU to discuss ways to improve the framework for system deployment.