Reduction of CO2 emissions in urban areas through optimal expansion of existing district heating networks

Abstract

In urban areas, district heating (DH) represents a valuable technology for providing sanitary water and house heating to buildings, because of its technical and economic strengths and its potentials on reduction of pollutant emissions. In large towns, DH is often an evolving structure. Connection of additional buildings, without any modifications in the existing network, is a frequent option to be considered to avoid further investment costs. When additional buildings are connected, the circulating mass flow rates increase and the corresponding pressure and velocity values might be inacceptable because of the large vibrations. This represents a crucial technical limitation. The possibility of optimally exploit the existing pipeline to connect as much users as possible, within the technical limitations, is an interesting issue.In this work, a methodology for optimizing the connection of additional buildings in existing large DH networks is proposed. The methodology allows finding the optimal expansion in order to minimize the pumping costs. The approach is obtained by integrating a) a GIS tool for gathering the necessary information on the building position, request and type of heating system installed, b) a fluid-dynamic model of the network able to account for the technical limitations and c) an optimizer of the pumping system for minimizing the pumping costs. The model is applied to a large existing DH system. Results show that the proposed approach allows one significant expansion of the DH (about 26% of additional connections), with limited investment costs. As a consequence in terms of environmental effects, the increased use of the DH technology allows a reduction of CO2 emissions associated with home heating of more than 13%.