LowEx communities - optimized performance of community energy supply system with exergy principles

Abstract

Communities are characterised by a wide range of heating and cooling energy demands. This energy is mainly provided by the combustion of fossil fuels, which is responsible for greenhouse gas (GHG) emissions. While a lot has already been achieved there are still large potentials in providing heating and cooling energy more efficiently. At the community level, different renewable energy sources are available. These energies are characterised by high fluctuations and different qualities: e.g. photovoltaics as electricity (high-exergy) or low temperature (low-exergy) heat from e.g. thermal solar collectors or waste heat from industry facilities. Low energy qualities are of particular interest, because the low exergy (LowEx) supply of thermal energy is very efficient. The application of exergy principles is especially important, allowing the detection of different available energy-quality levels and the identification of optimal contribution to an efficient supply. From this, appropriate strategies and technologies with great potential for promoting the usage of low-valued energy sources (LowEx) and a high share of renewable energies for heating and cooling of entire cities can be derived. The paper presents the key ideas of the just started international co-operative work in the general framework of the International Energy Agency (IEA), the EBC Annex 64: "LowEx Communities - Optimized Performance of Community Energy Supply System with Exergy Principles"