Excess heat from research facilities in Brunnshög in Lund, Sweden
This planned low-temperature heat distribution network is in Lund, Sweden. The city is dominated by Lund University and will expand with a new major residential area called Brunnshög, located northeast of Lund. This description will present the expansion until 2035. This initial phase will consist of 110 hectare land area and a building space of 0.64 million m2 .
Within this Brunnshög area, two major research facilities have been located. The first one is the MAX IV Laboratory that is a Swedish national laboratory providing scientists with X-rays for research. The other research facility is the European Spallation Source (ESS) that is a multi-disciplinary research facility with 13 European nations as members.
Both research facilities will generate large quantities of excess heat. At full activity, the annual heat volumes can be estimated to about 200-250 GWh per year at various low temperatures. The aim with the low-temperature heat distribution network is to recycle this excess heat and use it for the new Brunnshög residential district. However, the expected heat demand from these buildings will only be 23 GWh in 2035. Hence, the future challenge will be to use further excess heat in the traditional Lund district heating system.
The Brunnshög network is a part of the 2013 Brunnshög agreement between the Municipality of Lund and the local infrastructure providers. Kraftringen is the municipal local energy provider in the Lund area that also own and operate this low-temperature heat distribution network. The first heat was delivered from this low-temperature network in September 2019. The heat demand for all new buildings in the Brunnshög will be at the NZEB level. The expected specific heat demand for planning the heat distribution network is 36 kWh/m2 .
The distribution network is designed for using a supply temperature of 65°C and a return temperature of 35°C. It will be a classic network configuration with two parallel pipes and one substation in each building. The network layout is presented Figure 83. The chosen supply temperature is the minimum supply temperature that can fulfil the Swedish legislation concerning the Legionella risk in hot water circulation system in the connected buildings.
The total trench length in the Brunnshög area will be about 6.5 km until 2035, and plastic pipes will be used for 2.8 km. These plastic pipes will be one innovation developed together with the Logstor pipe manufacturer, since these pipes will have a design pressure of 10 bar.
The first major lesson learnt is that it is not possible to use lower heat distribution temperatures than 65/35 °C when the classic network configuration is used with one substation for each multi-family building. Further lessons learnt will be communicated during 2021 through the COOL DH project that Kraftringen participates in order to support this pilot project.