Thermal Energy from Drinking water for District Heating A case study on the potential of the drinking water distribution network as a sustainable energy source for district heating in Göteborg.

Abstract

As an alternative to fossil fuels as energy sources for heating and cooling, there is thermal energy available in water that is left unused (KWR, 2022). Recovering thermal energy from drinking water (TED) presents itself as a feasible strategy to offer sustainable heating solutions for both newly developed and existing communities, facilitating the shift towards sustainable approaches to heating (KWR, 2022). The technology behind combining the water and energy sector through the supply of TED is already developed. TED installations have been implemented and operating in the Netherlands for about 15 years (Oesterholt & Moerman, 2022). Through the analysis of three sustainability criteria, the sustainability of TED at a candidate TED location of Göteborg Kretslopp och vatten in Göteborg, as an input to a local district heating network (DHN) for residential houses is explored. These three criteria are energy supply, costs per house and 𝐶𝑂2emissions. This report compared three DHN scenarios in Göteborg, based on the results of these criteria. The DHN scenarios that are compared in this report are: 1. TED in a DHN of 70 °C with the use of gas 2. TED in a DHN of 70 °C without the use of gas 3. The current conventional DHN of 86 °C in Göteborg. A heat and power chain template, provided by S. Mol (personal communication, June 7, 2023), is used to formulate the different scenarios, simulate, analyze and eventually compare them. From comparison of the different district heating (DH) scenarios in Göteborg, first of all it can be concluded that a DHN including a TED installation can meet the heat demand of approximately 1000 multi-family houses in Göteborg, with a thermal energy input of around 9 million kWh. With the same amount of thermal energy input from the current DH energy sources, approximately 600 multi-family houses in Göteborg can be heated. Secondly, further research must be done on the costs of the DH scenarios in order to enable comparison. Thirdly, a DHN including TED shows lower levels of 𝐶𝑂2 emissions compared to a DHN with the current energy sources. Thus, based on two of the three criteria, a TED installation is a more sustainable option in a DH system in Göteborg than DH using conventional thermal energy sources for multi-family residential housing in Göteborg. This research shows that Göteborg Kretslopp och vatten could fulfill a new role as energy supplier. The framework presented in this research gives insights into the theoretical potential of TED in a specific location and can be a good start for determining the theoretical potential of a TED project in a certain location and comparison of the sustainability of TED projects to other TED projects and heating systems. Further research is needed to map out other potential TED locations, which will give insights into the total potential of TED in Göteborg.