Ökologisch-technische Auswirkungen dezentraler Energieversorgungsszenarien mit Blockheizkraftwerken in elektrischen Verteilungsnetzen

  • Ecological-technical assessment of decentralized energy supply scenarios with combined heat and power systems

Smolka, Thomas Markus; Smolka, Thomas Markus; Schnettler, Armin (Thesis advisor)

1. Aufl.. - Aachen : Mainz (2009)
Dissertation / PhD Thesis

In: Aachener Beiträge zur Hochspannungstechnik 8
Page(s)/Article-Nr.: 147 S. : graph. Darst.

Zugl.: Aachen, Techn. Hochsch., Diss., 2008


Germany’s energy supply has received profound changes through revised general political conditions such as energy markets liberalisation, the promotion of renewable energy resources (wind, photo-voltaic, and biomass) and the planned back out of the nuclear energy programme. Furthermore, the close-down of multitude power plants because of technical reasons requires a construction of addi-tional generation units under modified allocation rules and conditions. Against this background, priority will be given to decentralized combined heat and power (CHP) generation units. However, it is not known which circumstances and influencing factors of high decentralized energy supply have ecological advantages compared to a centralized energy supply. Furthermore, impacts on integration of highly dispersed generation (DG) units into power grids are subject to further research. Hence, this thesis examines ecological and technical impacts of decentralized combined heat power generation units and adds further value to its assessment. Different scenarios of DG integration (decentralized, local and district heating with CHP units) will be analyzed and compared to a centralized power supply with conventional local heating systems. The integration scenarios are specified varying the identified influencing factors of the power generation mix of centralized power plants, the structure of conventional heating systems (heating mix), the fuel mix and the local heat-to-power ratio in distribution networks. Due to the evaluation method devel-oped in this thesis it is possible to evaluate and compare multitude decentralized energy supply sce-narios considering ecological and technical circumstances. These are then compared to an energy supply following the reference development without dispersed generation. In highly populated areas a CHP-integration should be realized in combination with local or district heating networks. Integration of decentralised CHP units into medium or highly populated areas shows a higher CO2- reduction potential compared to an optimization of present large power plants on the system level. Decentralized generation units with a high electrical efficiency are necessary if assessing a significant reduction in heat demand in future scenarios. Assuming a CHP unit dimension-ing on the local heat demand – as today’s customary – leads to an installed capacity which is much higher than the maximum electrical load. Here, feed in power in the overlaying system is likely to occur during light load times. This variation requires dimensioning of the CHP units according to the local power demand. Additional integration of electric consumer loads such as heat pumps, electrical air-conditioning or electric vehicles can be an opportunity to reduce generation into the overlaying system. Fuel cells do not have any ecological advantage compared to CHP units equipped with inter-nal combustion using standardized natural gas. Only using Hydrogen as one of all renewable sources that cannot be integrated into the energy supply system (e.g. surplus funds of wind energy) leads to ecological advantages. The integration of dispersed generation with CHP units is a local implemented method reducing green house gases and increasing energy efficiency in distribution networks. In addition to the promotion of CHP integration in distribution networks a national strategy has to be implemented in order to achieve the targets of the formulated environmental production by reducing the consumers’ energy demand and improving the electrical energy mix of the overlaying system.