The district heating of the future is already underway in Brunnshög
In the research and innovation area Brunnshög, sustainable urban construction is prioritized in many different ways. One example is that the new properties where 40,000 people will live and work are low-energy houses. But even low-energy houses need supplementation of heat, albeit in a smaller amount than usual. A challenge in areas with low energy houses is that it can be complicated to build an economically viable district heating network — after all, the heat will still have to be produced and the wiring will still have to be installed, and the expected revenues may not correspond to these costs.
Therefore, the combination of housing together with the large research facilities ESS and MAX IV located on the site is very successful. The power ring saw early on that the residual heat from the research could be used for district heating to heat homes and other properties.
“Max IV can produce 28 GWh of residual heat per year,” says Anders Jirdén, project engineer at The power ring. We have estimated future needs in Brunnshög at 23 GWh/year, and this means that only residual heat from Max IV will be able to supply Brunnshög. In addition to this, ESS will also produce large amounts of residual heat. Although the residual heat has a low temperature, it was obvious that we wanted to use it as efficiently as possible. The solution was Kraftring's low-temperature district heating system.
The residual heat from the research facilities is kept at a low temperature, so the temperature of the residual heat from Max IV is increased in the power centre of Krafringen. An advantage of the low temperature system is that the temperature does not need to be raised as much as in a conventional district heating network, and the less the temperature is raised, the lower the production cost. Another advantage is that it fits well in low-energy houses. Houses built according to previous standards require significantly warmer water in the district heating pipes, while the energy-efficient homes built in Brunnshög have a lower need. There, the district heating is needed above all to heat the tap water in the taps to at least 55 degrees to keep legionella bacteria away. Therefore, the temperature for low-temperature district heating in Brunnshög is 65 degrees, which is much lower than in the traditional district heating network, where the water can be heated to over 100 degrees in winter. In addition, the constancy decreases when the pipes are laid in place.
“Lower temperature in the grid means that it is possible to use a new type of district heating pipes and thus a different laying technology, and this reduces the costs of the district heating network,” says Anders Jirdén. The pipes used in ordinary district heating networks must therefore withstand boiling hot water, in which case the district heating systems consist of 12 to 16 meters long insulated steel pipes that are welded together and the joints are insulated. These pipes are not bendable, they should be welded together, and in turns, pre-made bends are needed. The pipes for the next generation district heating do not have to contain a steel pipe, but it goes well with plastic pipes. These plastic pipes are flexible, the pipes come on 100-meter rolls and it is faster to put them into the ground. This is the key to keeping costs down.
The power ring encourages property owners to have a well-maintained facility that takes good care of the water. An optimal plant sends back water that is much lower in temperature than that water that came in, and that's good for the system throughout the area. Kraftringen therefore has a special price model in Brunnshög, which benefits everyone who can send cold water back — while at the same time it becomes a way to increase climate benefits.
The well pile will be expanded gradually and is expected to be completed around 2050, and the residual heat from MAX IV will thus be enough to heat the entire area. At MAX IV, Krafringen's energy center is located where the residual heat from MAX IV is converted and sent to Kraftring's traditional district heating network as well as Kraftring's low-temperature district heating network. If no residual heat is produced, the low-temperature district heating network is heated by the traditional district heating network.
“In conclusion, we see that the low-temperature system built in new district heating areas in combination with residual heat provides an excellent economy and a sustainable system,” concludes Anders Jirdén.
Links
Brunnshög - the city of the future is emerging in northeastern Lund | Kraftringen
The opening of Kraftringen's district heating network.
Other articles in our series about sustainable Brunnshög
At Brunnshög there is competition in sustainable construction
Car-free and comfortable at Brunnshög
Underground system manages garbage collection at Brunnshög
Aesthetic dams solve water problems at Brunnshög
Residential houses for water fans