Data centers and energy systems: an on-site integration

Data centers today consume between 2% and 4% of the electricity worldwide. Small data centers are responsible for half of this consumption. Data centers continue to expand rapidly and this presents a threat to their sustainable operation. Aquifer Thermal Energy Storage (ATES) is one of the promising technologies for cooling of data centers. ATES consists of two boreholes, which serve as cold and hot storage. One of our case studies in Denmark recently installed the ATES storage. During summertime, cold is extracted from the ground to provide cooling for data centers, while in winter it’s recharged with free coolers that can operate when the temperature outside falls below 8 oC. However, as a consequence of the climate change, summers are becoming hotter, and winters are becoming milder, creating an imbalance in the projected operation. In order to improve the operation of the ATES, an on site integration of heating and cooling systems is proposed. A mixed integer optimization model was developed for on site integration of heating and cooling systems. The
model takes into account operational constraints of the system and also serves as a capacity expansion model. The results showed that two heat pumps, using ATES hot storage as a heating source, should be installed, with capacities of 200 kW and 240 kW, respectively. The payback period was calculated to be 6.51 years, while the internal rate of return was 13%. Gas consumption for district heating dropped by 76% and CO2 emissions reduced by 49.6%. The results showed that there are still low-hanging fruits regarding the data center energy efficiency. However, data centers need to be fully integrated to the energy systems.