Green IT: Clever use of waste heat from data centers
Politics and business are currently struggling to find an affordable and sustainable energy supply. One area that requires alternate heat sources is the heating market. According to the Federal Environment Agency, about half of all energy consumption in Germany is devoted to heating and cooling, with almost 30% of final energy consumption coming from space heating alone.
Despite the fact that the share of renewable energies in the electricity sector is increasing constantly and has already surpassed 40%, their share in heating and cooling will only reach 16.2% in 2021. In search of alternate heat sources, the waste heat generated by data centers comes into view.
The power requirements of data centers are constantly increasing and in case the trend of data center construction continues, the energy requirements of data centers in Germany alone are estimated to increase from 17 billion kWh in 2021 to about 30 billion kWh in 2030. In turn, this waste heat could be utilized to heat tens of thousands of homes around the country. According to an estimate by Bitkom, up to 350,000 apartments in Germany could be heated with data center waste heat, although the waste heat from data centers is hardly used on a larger scale in the country.
The legislature is pushing for the use of waste heat from data centers. The EU Commission in its position statement on “Shaping Europe’s digital future” called for data centers to reuse their waste heat in 2020. Meanwhile, the coalition agreement of Germany’s traffic light government calls for the use of waste heat as well. With the Energy Efficiency Directive at the EU level and the Energy Efficiency Act in Germany, legal regulations for the use of waste heat are underway.
Obstacles to the use of waste heat
Although data center waste heat poses a promising alternative heat source, there are a few major roadblocks to its large-scale use. One significant issue is caused by the characteristics of the waste heat leaving the data centers. The hot air generated by the servers in the data center reaches a temperature of about 30 to 40 degrees Celsius and has high humidity due to the cooling system in data centers. This moisture content leads to higher corrosiveness, increased deposits, and fouling of heat exchangers – making it difficult to employ the heat directly for heating purposes.
Another challenge of using waste heat is the lack of a comprehensive and integrated value chain for waste heat usage. Waste heat is usually only used close to the data centers themselves for heating purposes, but there are a few isolated cases of district heating systems using waste heat for a large amount of apartments, such as the Elbe River in Hamburg. In addition, there is also no standardized approach or methodology for the assessment of waste heat projects from both a technical and economic perspective, making many companies hesitant to invest.
The choice of cooling systems
Data centers employ costly and sophisticated cooling systems that are currently not designed for waste heat recovery; instead, their sole purpose is to maintain the temperature of the server hall. The cooling design that permits waste heat usage reduces cooling efficiency and required specific designs at the data center’s network level. Using waste heat as a resource can also lead to higher maintenance costs on the cooling equipment, which is an issue that has to be considered while calculating the investment costs in the waste heat recovery facilities.
Key figures for assessment
It is important to make comprehensive assessments of waste heat projects from both a technical and economic standpoint to overcome the obstacles mentioned. To do so, a comprehensive and standardized energy-efficient assessment methodology is required, along with technical and cost benchmarks, comprehensive datasets from data centers, and a heat utilization network to connect data centers and consumers.
Although there are challenges and obstacles to the usage of waste heat from data centers, this powerful resource holds the potential to heat up several tens of thousands of homes across Germany. A concerted effort by regulators, data centers, and technology players to develop an integrated value chain, a standardized evaluation methodology, and ready investments will help unlock the full potential of waste heat and pave the way for reaching climate goals through a more sustainable and affordable energy system.