As the world is escalating towards decarbonization, Energy Storage System (ESS) installations are being constructed at a record pace. These systems are emerging as an integral component to a resilient and efficient electrical grid. ESS is primarily driven by Renewable Portfolio Standards (RPS) for power generation, peak shaving, and grid load balancing.
ESSs help reduce Carbon/Green House Gas (GHG) emissions by curtailing fossil power generation when the electrical grid is taxed with high demand.1 ESS provides a fairly simple, cost-effective way to stabilize a power grid, manage peak loads and balance loads, and help manage high and low outputs in power generation from renewable sources such as wind and solar. Load balancing helps smooth the intermittent nature of renewable energy sources such as solar and wind, thus making the grid more stable, reliable, and resilient. As more renewables are installed, grid stability becomes an ever-increasing issue.
While the concept of ESS is not new (batteries have been around a long time), there has been a marked increase in the deployment of larger-scale and higher energy density Li-ion batteries used in modern Energy Storage Systems. These ESSs can be collocated in a wide variety of occupancies.
While there are many benefits to ESSs, there is also the risk of fire loss. The fires are extremely hard to extinguish because of the battery chemistry and the exothermic process. The flammability of the Li-ion electrolyte is a concern, and research is ongoing to produce non-flammable or reduced flammable electrolytes by additives or developing non-organic ionic liquids that offer the same high performance as Li-ion. Recently the primary safety focus has shifted to the fire hazards associated with Li-ion batteries and the potential for a condition known as “thermal runaway.” Thermal runaway results from internal shorts inside a battery cell which can occur due to a variety of reasons which ultimately can lead to a fire. Preventing a thermal runaway event in the first place is the most important factor in preventing losses.2
Since recent popularity surge, there have been several losses involving Li-ion batteries between 2017 and 2021 worldwide, including South Korea (23 fires), England, Beijing, Australia and the United States. These can be challenging to control; the Australia fire involved two adjacent containers, 150 firefighters, 30 vehicles and took 3 days to extinguish. Since the fire could not be truly extinguished, the firefighters were limited to cooling the outside of the containers to stop the spread/damage to adjacent containers.
ESSs are a set of batteries that get charged and discharged at opportune times. They can be used to supply electricity to utility grids, local microgrids (e.g., campuses and neighborhoods), or the building in which the ESS is located. The ESS collects electricity from various potential sources, including the utility’s grid (usually during low demand pricing rates), solar and wind installations, generators, or other sources.
The anatomy of ESSs revolve around a system of interconnected components, hardware, and software and can include batteries, battery chargers, battery management systems (BMS), thermal management systems (e.g., HVAC), and associated enclosures. BMS systems control the operation and safety of the system to prevent thermal runaway and other abnormal parameters.
Li-ion battery-based systems are a common ESS design due to the inherent power density advantages of lithium chemistries. However, it should be noted that ESS and Li-ion batteries should not be considered synonymous. Other chemistries, including traditional lead-acid batteries, and other technologies such as a “flow” ESS using chemicals such as vanadium, can be used. ESSs are typically installed in a building, outside a building within a smaller rated enclosure (to NEMA, IP or other equivalent rating), or within larger intermodal containers.
The Battery Management System (BMS) is the brain behind the ESS. A well-designed BMS protects and monitors a lithium-ion battery to optimize performance, maximize lifetime, and ensure safe operation over a wide range of conditions. These conditions include overvoltage/undervoltage, overcurrent, short circuit protection, overtemperature, and cell imbalance. Make sure you have a proven BMS used in your ESS. Ultimately, it is the lifeblood of your system and your early warning system to alarm and shut the system down. Furthermore, BMSs are crucial for your ESSs ongoing Operation and Maintenance (O&M) efforts.
When located within a building, the ESS is usually installed in cabinets within mechanical and electrical rooms and will rely on the base building support systems. When installed outside a building, the enclosures typically contain thermal management systems (e.g., HVAC), supporting electrical and fire protection equipment.
Energy Storage Systems are here to stay, and installations will only grow exponentially over time. In fact, ESS is considered by many energy experts the ‘holy grail’ in terms of addressing the world’s clean energy future. As technology expands on these systems, it will become safer and safer as new chemistries are discovered and implemented into the industry.
These systems fill the gaps between conventional power generation and renewable energy production. They will be crucial for lessening the burden on an aging electrical grid by lessening consumption demand and smoothing out the intermittency issues of renewables.
In summary, ESSs ultimately prevent grid instability, save money over time, and reduce the carbon footprint, which creates a winning combination. Therefore, it is crucial not to introduce unintended consequences into these systems by designing and protecting them with the best available technology and know-how possible.