Alternatives to lead-acid and lithium batteries are gaining market share because they provide the growing number of energy storage reliant systems with new opportunities to reduce costs, increase performance, and improve environmental sustainability. These emerging battery chemistries offer advantages like high power and energy density, improved safety and reliability, better recyclability, smaller carbon and water use footprint, and lower toxicity. However, many operators may not understand which collection of alternative benefits to select for their systems.
Diverse and expanding choices of battery chemistries also enable commercial markets to avoid the limitations of a traditional or single new battery chemistry. Instead, users can incorporate multiple battery types into their applications to support the requirements that each chemistry is best suited to address. Control algorithms can switch between battery types, based on dynamic and evolving requirements, to simultaneously improve both system performance and operating costs without the need to sacrifice one benefit for another.
Complimentary batteries within a microgrid
Microgrids provide a key platform to showcase complementary capabilities of alternative battery chemistries. For example, the integration of both power-dense batteries and energy-dense batteries into the same microgrid improves deployment flexibility, safety, and operational performance.
Each battery brings complementary strengths to the microgrid system. For instance, high-power density batteries can quickly release vast amounts of energy. This makes high-power batteries ideal for architectural optimization of starting, bridging, peak shaving, and rapid de-energization applications. Nickel zinc (NiZn) is an example of a high power-density battery that offers high discharge rates to achieve microgrid operational goals while also lowering system cost per kW, eliminating the risks of thermal runaway, and improving overall environmental sustainability.
In contrast, high energy-density batteries typically have limited energy release rates; however, they can store more energy to support extended runtime applications. Lithium batteries are a great example of a high-energy-density battery that supports multiple-hour base load charge and discharge applications.
Microgrid systems increasingly use both battery types: high power density batteries for starting, bridging, and peak-shaving, and high-energy density batteries for base load support with prolonged charge and discharge applications. This combination of both battery types within a typically AC-coupled microgrid architecture optimizes many aspects of microgrid-supported applications.
Hybrid approach use cases
Since a “one-size-fits-all” battery solution does not exist yet, a variety of battery characteristics are required to support microgrids’ functional optimization. Two situations that benefit from this combined battery chemistry use are peak power-shaving and electric vehicle (EV) charging.
Peak power shaving is the use of battery storage to supply power to a microgrid when power demand and its ensuing costs are highest. This strategy helps operations save money while maintaining disruption-free microgrid functionality. As the transportation economy electrifies, it increases power supply stress on the grid, which in turn increases the grid’s reliance on battery energy storage. While high energy-density batteries (such as lithium-ion) are well adapted to support long-duration power demand, they often are not powerful enough to meet short-term peak power demand. At these times, high-power density batteries like NiZn can respond on demand to support those types of short-term microgrid power requirements.
Another example is the power battery use case for EV charging in environments with fluctuating demand. As the number of EVs on the road increases, so will the demand placed on charging stations. Most battery-powered EV charging stations can support simultaneous demand for only a few level 2 charge sessions. The increase in demand for high power level 3 charging, and simultaneous level 3 charging of multiple EVs, is driving the need for high power batteries. By incorporating multiple battery chemistry options into a single charging station, the system can adjust between providing longer duration, lower power charging or faster, higher power charging based on the needs of the situation.
Different battery types for optimized performance
The days of “one battery chemistry for all application requirements” are ending. As a wider variety of high power and high energy density battery chemistries become available, hybrid battery approaches have clear performance benefits while offering opportunities for significant cost and environmental advantages. Today and in the future, using multiple battery chemistry options to optimize overall microgrid application performance just makes sense.
This post originally appeared in Renewable Energy World.