Using Energy Storage Technology to Support Distributed Energy Applications

Our power grid is becoming more distributed and more renewable than ever. Energy storage is a critical technology component to reducing our dependence on fossil fuels and building a low-carbon future. Without it, the shift to renewables will be impossible. Microgrids, net zero buildings, and local renewable energy resources are all enabled by energy storage.

Battery energy storage systems improve grid resiliency. Every year more systems, including vehicles and data centers, increasingly rely heavily on electricity. This increased demand for power places strain on grid infrastructure. In addition to modernizing the electrical grid—an important project that is well underway—building more energy storage can help take pressure off the grid for grid operators (Figure 1). Residential homes or small communities can also improve energy independence by connecting battery energy storage systems to distributed energy resources (DERs) like rooftop solar, and reduce energy costs by using stored power during times when grid power is particularly expensive.

DERs are electricity generation systems that include several small-scale devices located closer to the demand, as opposed to a centralized power plant and distribution network. A DER is also referred to as a distributed energy grid. DERs play an increasingly significant role in the transition toward cleaner energy systems as businesses and individual consumers add energy generation capabilities to their homes and businesses.

This article is included in “Coming Together for Clean Energy,” POWER’s publication that is aligned with RE+, the largest renewable energy trade show in North America. RE+ is happening Sept. 9-12, 2024, in Anaheim, California. To continue the conversation around clean energy, plan to attend POWER’s EP Week event in Orlando, Florida, Oct. 9-11, 2024.

DERs Are Made Possible by Energy Storage

There are fundamental differences between traditional fossil fuel energy and the renewable energy used in DERs. Wind and solar energy rely on the wind blowing and the sun shining, whereas centralized non-renewable resources like coal can be burned whenever power is needed.

Energy storage is critical in distributed energy systems to decouple the time of energy production from the time of power use. Using energy storage, consumers deploying DER systems like rooftop solar can, for example, generate power when it’s sunny, and deploy that power later during the peak of energy demand in the evening. Consequently, energy storage systems play a pivotal role in advancing clean energy objectives by enhancing the efficient utilization of renewable resources and simultaneously enhancing grid reliability and stability of pricing.

In addition to applications along the grid, energy storage is also used in commercial and industrial applications to enhance reliability of energy availability, and reduce costs by using stored power during times when grid power is particularly expensive. Residential homes or small communities can also use energy storage to achieve better energy independence and environmental sustainability by connecting energy storage systems to distributed energy resources like rooftop solar.

Important Considerations for Implementing Energy Storage

The International Renewable Energy Agency estimates that 90% of the world’s electricity may come from renewables by 2050. This necessitates a massive increase in renewable power generation. However, there are a few key considerations to keep in mind when implementing energy storage:

• Footprint Reduction: Given the limited physical space available in various applications like grid installations, electric vehicle (EV) charging stations, and commercial and residential buildings, reducing the footprint of energy storage systems is crucial. This involves optimizing technology and design to maximize the storage capacity within a smaller physical footprint.
• Infrastructure Support: Energy storage installations require appropriate infrastructure support to accommodate the batteries and associated components. This includes considerations for cooling systems, electrical connections and structural support to ensure efficient operation and safety.
• Scalability: The ability to scale energy storage systems according to demand is critical, especially in applications where growth is anticipated, such as microgrids and EV charging stations. Modular designs that allow for easy expansion or replication of storage capacity can support future needs effectively.
• Regulatory Compliance: Compliance with regulatory standards and guidelines related to safety, environmental impact and grid interconnection is essential. Ensuring that energy storage installations meet all relevant regulations and standards is critical for successful implementation.
• Cost-effectiveness: Assessing the overall cost-effectiveness of energy storage solutions, a user must weigh upfront costs and maintenance expenses against potential savings and/or new business opportunities from improved energy management. Implementing systems that offer a favorable return on investment over their lifecycle is key to widespread adoption.

Technologies to Support Growth in Energy Storage

Those looking to implement battery energy storage systems in distributed grid applications need to find the right technologies. While needs might be different depending on the scale of an installation, and many battery energy storage manufacturers sell complete systems, the performance of the following technologies will affect the performance of energy storage systems as a whole.

Cooling Technology: To maintain both performance and safety, batteries must be cooled. There are a wide range of cooling technologies deployed in energy storage systems depending on the power density of a particular installation. Air conditioning is a good solution for many systems. Air cooling is becoming more efficient, and many companies are taking a look at the refrigerants they use to make them more environmentally friendly. For installations with higher energy density, liquid cooling is often a better option due to superior efficiency and effectiveness.

Liquid cooling (Figure 2) is a spectrum of technology pioneered by the data center industry but extremely useful in energy storage as well. In data center applications, it ranges from using chilled liquid lines to supplement the performance of air cooling to completely submerging equipment in nonconductive liquid. Liquid cooling is an effective cooling technique because liquid provides a much greater heat transfer capacity than air. It can also be pumped closer to the source of heat, capturing and transporting heat out of the system from the point at which it is generated. This helps liquid cooling increase power usage effectiveness, manage heat loads effectively, reduce energy costs and contribute to environmental sustainability.

Liquid cooling works in battery energy storage applications by using a chiller to pump cooled fluid through the system in a closed loop, with precision control adjusting fluid temperature and flow rates to maximize efficiency. Hot or cold liquid is pumped through hoses and manifolds to racks of batteries. Liquid is then pumped through cooling lines to each individual battery and back to the chiller where it is cooled and recirculated. The entire system is a completely closed loop, so risks of leaks or liquid coming into contact with electrical infrastructure are minimized. However, to reduce the risk of leaks, reliable systems are a must.

In the same way data center managers want to prioritize using power on computing instead of cooling infrastructure, battery energy storage system manufacturers want to reduce total cost of energy, or TCOE. This represents the cost of running an energy storage installation including the supporting infrastructure. By raising the cooling capacity of energy storage systems with liquid cooling, battery module manufacturers can fit higher energy dense batteries closer together and increase the total power capacity of their installations without extreme increases in the cost of energy spent on cooling.

Flexible Conductors: Even with batteries appropriately cooled, they need to be connected to one another, and to whatever applications they are powering. Traditional cable solutions, while appropriate in some applications, can be difficult to use when footprint reduction is a primary concern because they often do not have a safe bending radius to accommodate tight turns in small spaces. In these instances, flexible conductors, such as flexible busbars or braids, can offer more design options due to their reduced cross-section and minimal bend radius requirements. These busbars can be prefabricated to save time and labor on job sites.

Advanced Battery Technology and Materials: The development of advanced materials and environmental protection, such as lightweight and durable enclosure materials, reliable gasketing and enclosure designs, thermal cable coatings, fire-resistant materials and low-smoke zero-halogen insulation, contributes to the safety, efficiency and longevity of battery energy storage systems. The development of battery technology itself, alongside the technology that supports it, is fundamental to these systems. Lithium-ion batteries are commonly used due to their high energy density, scalability and relatively long lifespan. Lithium iron phosphate technology has come a long way and is helping reduce TCOE for energy storage users.

Demand for energy storage will continue to grow as government investments in infrastructure increase around the world, and microgrids become more common. Data centers are built to support the expansion of artificial intelligence, and EVs are experiencing widespread adoption. Reducing the footprint of an energy storage system, while providing reliable environmental protection, liquid cooling and efficient electrical distribution and grounding for such systems will be a challenge for battery module manufacturers, power companies, commercial buildings and more. Thinking about these challenges and developing technology to address them now will help energy storage companies get out ahead of the competition.

—John Turner is Vertical Growth Leader, Energy Storage and Renewables, for nVent.