Flexible energy systems:integration of electricity production from CHP and fluctuating renewable energy

Renewable energy sources and distributed generation play a crucial role in supporting the European Union's key policy objectives of combating the greenhouse effect. In order to bring about a substantial long-term penetration of distributed energy resources in Europe, one of the most important future challenges seems to be the management of the integration of fluctuations in electricity production from renewable energy sources and CHP. In Denmark approximately 15% of electricity demand is produced by wind power, and approximately 50% by CHP, and both technologies are intended for further expansion in the coming decades. Even now the high percentage of wind and CHP causes problems, and based on the existing energy system with large steam-turbine plants, it has been estimated that Denmark, in the year 2030, will be forced to produce approximately 45% more electricity than needed simply because of regulation problems, i.e. problems of producing electricity in accordance with fluctuations in demand. This paper discusses and analyses different national strategies for solving this problem and points out key changes in the energy system in order to achieve a system which can benefit from a high percentage of wind and CHP without having surplus production problems, introduced here as a flexible energy system