The City of Brunswick
Brunswick (Braunschweig) is the second largest city in Lower Saxony, Germany, with 250,000 inhabitants. The region of Brunswick is one of the leading European regions with regards to spending on research and development. The city prides itself to be a hub of versatile industry expertise, including technology and innovation, energy and environment and medicine and healthcare. In addition, the region is home to 300 leading IT companies.
The Brunswick demonstration site is run by Veolia’s subsidiary BS|ENERGY, which is a local energy provider for electricity, heat, gas and water in Brunswick. It operates an existing district heating grid that provides 45% of the city, powered by high-efficiency cogeneration plants.
The district heating network will be expanded to a residential area with approx. 400 housing units, which is currently under development. Just next to this residential area, a data centre was built. A data centre has an extensive cooling demand, which in return produces excess heat.
With this setup – a residential area that needs heating and a data centre next to it that produces excess heat – Brunswick is a perfect candidate to test the highly innovative ReUseHeat heat recovery solution for data centres.
The newly built energy-efficient housing area will enable the deployment of a low-temperature 4th generation district heating network. The base load is expected to be fully covered by the waste heat potential of the data centre. Peak loads will be covered through a connection to the existing CHP-powered high-temperature district heating network.
A data centre requires constant cooling to maintain a moderate climate in the computer room. This excess heat produced during the cooling process can be discharged to the ambient air through so-called free cooling. Then, a heat exchanger cools the inner air by transferring the heat to an outside air flow of lower temperature. Free cooling is, of course, only available in the cold periods of the year. In the warmer times usually compression chillers are used to cool the server space.
Free cooling and especially the compression chiller can partly be replaced by a heat pump system to make use of the waste heat for heating and hot water purposes.
Due to the low temperature of the heat source, a heat pump will be used to increase the supply temperature. At the same time, keeping the temperature level of the supply as low as possible is desired for high efficiency. A smart control solution, taking into account the real-time data from the substations, will control the heat pump. All substations will be equipped with sensors to collect data and feed this information into a central control system. Thus, it will be possible to operate with maximum efficiency and enable also low return temperatures, while being able to provide real-time feedback to the customer.
On December 13th, 2021 the commissioning of the data center heat recovery took place. The cooling fluid (CO2) was filled into the heat pump. After this first test of heat recovery, the test of the heat pump took place. BS-Netz as the operator of the heat pump was supported by the heat pump manufacturer to find the optimal parameter settings and to check whether all data are available on the control systems
After two days of testing the commissioning was finalized and the heat pump went in operation. The next step is to increase the available heat load for the heat recovery to get a high ration of waste heat in the total heat supply of the low-temperature network.
More information on heat recovery from data centers.