Data Centers: Efficient Energy Use and Water Conservation

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

Data centers are notorious for their high energy consumption, particularly in cooling processes that maintain IT rooms at optimal temperatures. Cooling alone can account for over a third of a facility's total electrical energy demand, making energy efficiency a critical focus for data center operators and stakeholders. This demand is driven by the necessity to keep thousands of servers functioning at operational temperatures, preventing overheating and ensuring continuous, reliable service.

One key metric used to evaluate this efficiency is Power Usage Effectiveness (PUE), which measures the ratio of total facility power to IT equipment power. Over the past 15 years, the average PUE for data centers has improved significantly, dropping from 2.5 to 1.6. New facilities, leveraging advanced technologies and design practices, are now capable of achieving PUEs as low as 1.2, setting new standards for energy efficiency.

As energy efficiency improvements become increasingly challenging, the industry's focus is shifting toward water usage as a critical factor in sustainable data center operations. Water Usage Effectiveness (WUE) is emerging as an important metric, reflecting growing concerns about the substantial water requirements of data centers, especially in regions where water is scarce.

This shift is driven by environmental concerns and increasing scrutiny from regulatory bodies, customers, and the public, all demanding more sustainable operations. As computing demands rise, fueled by the expansion of cloud services, AI, and big data, the pressure on data centers to optimize both energy and water use will only intensify.

Reducing Water Usage in Cooling Processes

Data centers generate significant amounts of heat, necessitating effective cooling solutions to maintain optimal conditions and ensure hardware reliability. Traditional cooling methods often rely on water, such as in evaporative cooling towers, but these methods are increasingly viewed as unsustainable, particularly in regions where water is scarce. The need to conserve water while maintaining effective cooling has led to the exploration of alternative solutions that reduce or eliminate water usage.

One such alternative is low-energy, water-conserving cooling methods like free cooling or chilling, which use external air or natural resources. These solutions offer significant reductions in both energy and water consumption, making them attractive options for data centers seeking to improve sustainability. However, even in favorable locations, traditional cooling may still be needed during extreme weather, necessitating a hybrid approach.

As rack densities increase to support IT load growth, advanced liquid cooling solutions are emerging as promising alternatives for reducing water usage. Technologies like direct-to-chip or immersive cooling, where IT equipment is submerged in a thermally conductive but non-electrically conductive liquid, offer efficient heat removal. These technologies reduce or eliminate the need for water in cooling and improve overall energy efficiency by minimizing reliance on compressor-based systems. For instance, a recent case study demonstrated a 50% reduction in energy consumption by HVAC systems through these advanced cooling solutions, highlighting the dual benefits of reducing both direct and indirect water consumption.

Harvesting Rainwater and Bleed Recovery

When water-based cooling processes are necessary, facilities can reduce waste through rainwater harvesting and bleed recovery systems. Rainwater harvesting involves collecting and storing rainwater, typically from roofs, and treating it for use in cooling processes. This reduces reliance on municipal water supplies and minimizes resource waste.

Bleed recovery, where water is periodically discharged from evaporative cooling systems to reduce salt concentrations, is another effective method. By capturing and treating this water, it can be recycled back into the cooling process. Reverse osmosis and ultrafiltration are common bleed recovery methods, with ultrafiltration being more energy efficient. These approaches help reduce water consumption and waste, making them valuable tools for sustainability.

ENGIE increasingly incorporates these water-saving strategies, especially in regions with limited water availability. These approaches not only reduce environmental impact but also offer potential cost savings through lower water and energy consumption.

Trigeneration Using Absorption Chillers

Improving energy and water efficiency is crucial for reducing data centers' environmental impact. Trigeneration systems, which generate electricity, heating, and cooling simultaneously from combustion processes, offer a highly efficient solution. These systems are scalable and can adapt to the increasing IT load of data centers, providing a flexible approach to energy management.

ENGIE has developed expertise in engineering and operating trigeneration systems across various industries, including data centers. These systems often use gas turbines or engines running on a mix of fuels, including natural gas, hydrogen, and biogas. As green fuel supply chains develop, the goal is to transition to 100% renewable energy sources, further enhancing sustainability.

Trigeneration systems recover waste heat from combustion and transfer it to absorption chillers, which then cool the data center. This approach is more efficient than traditional designs, which rely on grid power and diesel generators for backup. By reducing net energy losses, trigeneration improves both PUE and WUE, offering a comprehensive solution to energy and water efficiency challenges.

Case Study: Middle East Data Center

A recent project in the Middle East demonstrates the potential of innovative energy solutions. Faced with grid limitations and water scarcity, ENGIE and RED designed a data center with hydrogen-ready gas turbines and heat recovery steam generators. Combined with a solar farm, this system aims to create one of the greenest data centers in the region.

The solar farm will eventually supply electricity to the data center and an electrolyzer, producing green hydrogen for the turbines. This integrated approach enables the data center to achieve exceptional PUE and WUE close to zero, even in harsh conditions, while maintaining energy security and Tier III Uptime compliance.

Conclusion

In response to the challenges faced by data center operators, ENGIE offers innovative solutions that can drastically reduce—or even eliminate—water consumption. By adopting advanced cooling technologies, rainwater harvesting, bleed recovery, and trigeneration systems, data centers can achieve greater energy and water efficiency, contributing to a more sustainable future.

No matter the local constraints or stage of development, ENGIE has the expertise and solutions to optimize your energy usage and spending. Our team of experts is ready to help you enhance efficiency, reduce costs, and meet sustainability goals. Contact us today to explore how we can support your data center's journey toward optimal energy management.