A new study from Rice University in Houston, Texas, has explored the potential of converting waste heat from data centers into a dispatchable power source.

The study published in the journal Solar Energy, introduces a solar thermal-boosted organic Rankine cycle (ORC) system as a potential solution for waste heat recovery in data centers.

ORC is a thermodynamic system that converts low-temperature heat into electricity using an organic fluid with a low boiling point instead of water.

Conventional ORC systems can generate electricity from low-temperature waste heat, but their efficiency is limited in these applications.

Instead, the researchers proposed a new system that integrates solar flat plate collectors (FPCs) with the ORC to increase the temperature of the heat transfer fluid, thereby improving efficiency without requiring additional electricity consumption. The researchers found that the added “solar bump” can overcome the fact that data center waste heat is usually too cool to be utilized for efficient power generation alone.

The study incorporates techno-economic modeling and simulations, featuring case studies in Ashburn, Virginia, and Los Angeles, California, two of the most high-density data center locations in the US.

Results from the research showed that the solar boosting increased ORC efficiency by more than eight percent during peak solar hours. On an annual basis, ORC power output rose by 60 percent in Ashburn and 81 percent in Los Angeles.

The levelized cost of electricity decreased by 5.5 percent in Ashburn and 16.5 percent in Los Angeles. Sensitivity analysis indicated that solar boosting provides greater economic benefits at lower waste heat recovery temperatures.

In their concluding statements, the researchers argued that integrating solar thermal collectors with ORC technology offers a cost-effective way to enhance waste heat recovery, reduce operating costs, and lower the environmental impact of data center operations.

At present, data center waste heat has been primarily utilized as part of district heating systems. Solutions such as these have been most successful in Europe due to its legacy district heating infrastructure and supportive regulations.

Recent examples include an agreement in the French city of Toulouse, which will see heat from two supercomputers supplied to the local district heating network, and a deal in the German city of Norderstedt to repurpose heat from its own data center for use in the local district heating network.