Contribution of decentralized combined heating and power units to reduction of CO2 emissions and an affordable energy supply

A study was conducted to determine the energy strategy in Germany that can achieve maximum reduction of greenhouse gases (GHG) in residential heating at an affordable cost. The energy consumption, efficiency and modernization frequency of existing buildings and their heating appliances were analyzed. Several scenarios of frame conditions were used to estimate future development in the power and heat generation sectors. Results show that the combined strategy of energy offensive scenario could achieve the goal for CO2 reduction without additional cost compared to the business as usual scenario (12 EUR per ton of reduced CO2). In contrast, the energy concept scenario needs much more investments, which cannot be compensated by energy savings. The necessary cost per ton to reduce CO2 will be about ten times higher at 124 EUR. An additional effect is the stabilizing of power generation from renewables by combined heat and power (CHP) systems and the substitution of fossil power generation. In a forecast to the year 2050, renewable gas fired CHP power generation may substitute about 43% of fossil power plants.