Waste Heat Imperative: The Growing Importance of Waste Heat Recovery in Data Centers

By Patty Solberg & Maribel Adydan (Garza) , ENGIE North America Inc. , with contributions by Eric Lamendour

As data centers evolve, driven by the soaring demands of High-Performance Computing (HPC) and AI advancements, waste heat recovery has become increasingly critical to maximizing operational and sustainable efficiency. The increasing densities within data centers, driven by cutting-edge hardware advancements, result in significant heat generation that must be efficiently managed. This surplus heat is now seen as a valuable resource, prompting a shift toward harnessing it for beneficial use.

Waste heat recovery is not just an option but an essential component of modern data center operations. With global sustainability goals and regulatory pressures mounting, the urgency for efficient heat recovery practices has grown. Integrating waste heat recovery with local communities, businesses, and industries offers a dual benefit: it efficiently manages excess heat while creating opportunities for cost savings, community benefit, and possible revenue generation.

Integrating Data Centers with Local Communities

As data processing intensifies, nearly all IT processing power is dissipated as heat, posing challenges for heat rejection systems. Whether a data center uses condenser water, chilled water, or mass air flow, the total heat rejected remains constant. However, the temperature at which this heat can be efficiently harvested for district heating or direct consumers varies, as does the energy and water consumption required for heat rejection.

Urban district heating and cooling networks are gaining traction as low-cost, low-carbon solutions across residential, commercial, and industrial sectors. The evolution from steam-based district heating to modern low-temperature hot water systems has enabled more efficient integration of waste heat from data centers. These networks can capitalize on large volumes of low-grade heat, reducing carbon emissions and providing reliable heat to consumers.

Data centers, particularly those near urban and industrial areas, offer a significant source of low-grade waste heat that aligns well with the operational needs of these heating networks. Direct consumers, such as buildings with consistent high energy demands, can also benefit from the steady waste heat profile of data centers. Facilities like kitchens, swimming pools, and greenhouses, which require continuous heating, and industries operating year-round, are prime candidates for utilizing this surplus heat.

Expertise in Waste Heat Recovery

Experienced energy integrators like ENGIE play a crucial role in designing and implementing waste heat recovery systems for data center customers. These systems require careful planning and integration with local energy ecosystems to be both technically viable and economically sound.

Our process begins with a comprehensive exercise to identify potential heat consumers near both existing and greenfield data centers. Advanced modeling tools project daily heat demand profiles, aligning them with the heat rejection profiles of data centers. Optimizing these connections maximizes the energy harvested from waste heat, reducing environmental impact while providing reliable heat to consumers, along with reliable returns.

Methods of Waste Heat Recovery

The cooling system within a data center determines the potential for waste heat extraction. For water-cooled chillers, heat can be reclaimed from the condenser water loop; for air-cooled chillers, from the chilled water loop; and in mass air cooling systems, via a heat exchanger in the exhaust ventilation system.

The rise of liquid cooling technologies, such as direct-to-chip cooling and immersion cooling, is shifting the landscape of waste heat recovery. These technologies offer a higher-grade waste heat, with reclaimable temperatures ranging from 40 to 60°C. This temperature range enhances the efficiency of heat pump systems – and expands the potential consumer base for recovered heat.

By integrating advanced cooling systems with district heating networks, waste heat is efficiently captured and utilized, providing tangible benefits to both data centers and surrounding communities.

Recent ENGIE projects have successfully connected data centers to district heating networks, capturing heat from cooling processes and using it to generate additional heat. These initiatives demonstrate how waste heat recovery can be integrated into broader sustainability strategies.

Financing and Implementing Waste Heat Recovery Projects

Efficient waste heat recovery requires substantial investment, particularly in infrastructure for heat distribution. Partnering with ENGIE provides significant advantage through our expertise in developing such projects. By conducting thorough techno-economic modeling, we assess the risks and benefits of each waste heat recovery project, ensuring that investments are sound and projects are profitable.

Financing models are designed to attract investment while mitigating risks for all parties involved. This includes evaluating the distance between data centers and potential heat consumers, which directly impacts the size and cost of the heating network. Careful planning of these factors can optimize both operational efficiency and capital costs.

By forming long-term partnerships with stakeholders such as local municipalities and industrial clients, waste heat recovery projects can bring mutual benefit to the broader economic community. These partnerships, combined with technical & operational expertise, ensure that projects are executed smoothly, with clear contractual interfaces that minimize operational and financial risks for data center operators.

Conclusion

As data centers strive for net-zero carbon footprints, waste heat recovery schemes play a crucial role in community sustainability strategies. ENGIE has built years of expertise in designing, financing, and operating these systems as a key partner for data centers looking to leverage untapped energy resources. With the increasing adoption of efficient cooling systems in HPC data centers, the importance of reclaiming waste heat is set to grow. The evolution of district heating networks, designed to operate efficiently at lower temperatures, marks a pivotal opportunity for integrating waste heat recovery into broader energy strategies.

If you are looking to harness the power of your waste heat and see how waste heat recovery can support your operational and sustainability goals, contact ENGIE today to get started.