Design of Renewable Energy Production in District Heating System

Abstract

One way to decarbonise the heat supply in buildings by using environmentally friendly and highly energy-efficient equipment and technologies that save primary energy is through existing district heating systems (DHS´s) that supply several buildings at once. Many heat sources and equipment on the heat production and distribution side of these DHS´s are beyond their service life or use fossil fuels as an energy source. It is therefore necessary to modernize such systems through highly efficient and renewable energy sources (RES´s). As the Slovak Republic has a number of DHS´s, we have designed streamlining the existing heat source operation for the DHS of the West housing estate in the town of Brezno through a cogeneration unit (CU) and water - to - water heat pumps (HP´s). The existing heat source consists of three hot water boilers burning natural gas. In addition to the existing equipment, we designed a CU and HP´s, which would be used to prepare hot water. The flow of the heating heat transfer medium passes first through the HP´s and then through the CU. If the temperature of the working medium is not sufficient, the flow of heat transfer medium will also pass through the boilers. The operation of the CU and HP´s is designed in island mode, i. e. without external connection to the electricity grid. The proposal is based on real operational data provided to us by heat supplier for the period 2016 - 2018. We have assessed the proposal from the point of view of energy and economics. From the point of view of energy, we focused on energy consumption before the design of new equipment and the expected energy consumption after the design of new equipment. From the point of view of economics, we examined the return on investment. The aim of the proposal is to point out the importance of modernizing DHS´s, as they are an ideal place for the application of high-efficiency technological equipment and equipment using renewable energy.