Battery energy storage technology is emerging as a key technology in the shift towards sustainable and resilient energy systems. Battery storage technology allows electricity generated once to be used later. This simple but transformative function is becoming increasingly important. Innovative energy storage solutions become critical as we transition from fossil fuels to inherently intermittent renewable energy sources like wind and solar. Battery energy storage captures renewable energy when it is available and releases it when it is most needed, ultimately contributing to a more efficient, reliable ,and sustainable grid. This article will take an in-depth look at battery energy storage, how it works, and why it’s so important.
How Battery Energy Storage Works
Essentially, batteries store electrical energy as chemical energy that can be released as electrical energy as needed. The charging process converts electrical energy into chemical energy while discharging does the opposite. Battery energy storage systems typically manage the charging and discharging of energy through a complex control system to provide power when needed or when it is most cost-effective. Key components of a battery energy storage system include the battery system, power conversion system or inverter, battery management system, environmental control system, controllers, and safety equipment such as fire suppression, sensors, and alarms.
Importance of Battery Energy Storage
Battery energy storage is critical to the energy mix for a number of reasons. It supports integrating and expanding renewable energy sources and reduces dependence on fossil fuels. By storing excess energy generated when renewable energy generation is high (e.g., on sunny or windy days), battery energy storage helps mitigate the intermittency issues associated with renewable energy. The various energy storage applications can also improve grid stability and resilience, as they can respond quickly to grid supply and demand changes.
There are several key reasons why battery energy storage is critical:
Enabling renewable energy
Renewable energy sources such as wind and solar are intermittent and only produce energy when favorable conditions are favorable. The timing of energy generation from these sources does not always coincide with periods of high energy demand. Battery Energy Storage Systems (BESS) allow energy to be stored when production is high and then used when demand is high. Combining renewable energy with energy storage can increase the share of renewable energy in total energy.
Grid resilience and reliability
Our grid must evolve to cope with increasing volatility and dispersion as we move towards a renewable energy future.BESS stabilizes the grid by absorbing excess power during periods of high production and releasing it during periods of high demand. Using BESS in this way helps reduce outages and provides a more stable supply of power to the grid. This resilience is particularly important during extreme weather events, which are becoming more frequent globally.
Reducing emissions from peaking power plants
Peaking power plants operate only during times of peak electricity demand. These plants typically use fossil fuels, are less efficient, and emit more greenhouse gases.BESS reduces reliance on peaking plants by storing energy during low-demand hours and supplying it during peak-demand hours.
Supporting Electrification
Achieving a zero-emissions future will require the electrification of many industries currently powered by fossil fuels. This includes industries such as transportation and heating, transitioning from internal combustion engines and gas-fired boilers to electric-powered alternatives such as electric vehicles and heat pumps. The shift to electrification will increase demand for electricity and put additional strain on the grid. For more information on battery technology, check out our article on 3-7 volt battery types: a comprehensive guide.
Battery Energy Storage Systems (BESS) play a vital role in managing the growing demand for electricity and balancing electricity usage patterns. This allows electrical loads to be integrated into the energy mix without the need for significant increases in generation capacity. For example, a 100 kW/192 kWh BESS unit in California combined with a DC fast charging station demonstrates this capability.
On a smaller scale, BESS can support homes and businesses equipped with solar panels, storing excess energy for use on days without sunlight. This approach increases energy independence, reduces reliance on the grid, and minimizes energy production and transmission emissions.
Battery storage is critical to promoting renewable energy adoption, improving grid reliability, reducing emissions, and supporting electrification to achieve net-zero emissions goals. As industries transition to electrification and demand for electricity continues to grow, the need for battery storage will continue to increase.
Benefits of Battery Energy Storage Systems
A BESS offers a number of significant advantages that make it an increasingly important component of the energy sector. These advantages include:
- Grid Stabilization: A BESS can absorb or release power immediately, providing a critical service in balancing supply and demand, stabilizing the grid, and maintaining a stable frequency.
- Renewable Energy Integration: A BESS can store excess energy when generation from renewable energy sources, such as wind and solar, exceeds demand and release that energy when demand exceeds generation, such as when there is a shortage of sunlight or wind. This capability solves the problem of intermittency of these energy sources and improves their reliability and availability.
- Peaking: By storing energy during low-demand periods and releasing it during high-demand periods, BESS relieves the grid of power demand during peak hours. This “peaking” reduces the need for peaking plants, which are costly and often use fossil fuels to generate electricity, and therefore have economic and environmental benefits.
- Energy Arbitrage: BESS enables energy arbitrage by storing energy when prices are low and distributing it when prices are high, resulting in significant savings or additional revenue.
- Backup Power: BESS can provide backup power in the event of a power outage, increasing energy resilience and reliability for homes, businesses, and critical infrastructure.
- Grid independence and self-consumption: BESS increases the energy self-sufficiency of homes and businesses by generating electricity from renewable sources such as rooftop solar panels. It allows for the storage of excess power generated on-site for later use, reducing reliance on the grid and improving generation efficiency.
- Supports Electric Vehicle Charging: As electric vehicles (EVs) become more popular, combining BESS with charging stations ensures fast charging without overburdening the grid. By storing power during off-peak hours and releasing it during peak hours, BESS can expand available capacity and significantly reduce demand charges.
Utilizing BESS can solve many of the challenges currently facing the energy mix.
Types of Battery Energy Storage
Battery energy storage systems utilize a variety of battery technologies. The following are the most commonly used battery types:
- Lithium-ion batteries: The widespread use of lithium-ion batteries in energy storage systems is due to their high energy density, high efficiency and long cycle life. The main chemistries used in these systems include Lithium Iron Phosphate (LFP) and Lithium Nickel Cobalt Manganate (NMC).
Li-ion-based containerized energy storage systems are the energy storage solution of choice.
Lithium-ion batteries are known for their high energy density, long life and efficient charging and discharging capabilities. They have a low self-discharge rate and require little maintenance, making them the first choice for energy storage systems. Lithium-ion batteries are widely used for the following reasons
High energy density
Lithium-ion batteries have a very high energy density and can store large amounts of energy in a compact space. Therefore, they are well suited for limited space applications, such as electric vehicles or energy storage systems.
Efficiency and charge/discharge rates
These batteries are highly efficient in both charging and discharging, being able to accomplish both processes at relatively high rates. This high efficiency makes them ideal for applications that require rapid discharge or energy storage.
Long Life and Cycle Durability
Lithium-ion batteries have a long service life compared to many other battery technologies and can withstand multiple charge/discharge cycles. This extended cycle life ensures that the battery is cost-effective over its lifetime.
Mature Technology
Lithium-ion battery technology is mature and well known, reducing the risks associated with newer, less proven technologies.
Despite these benefits, lithium-ion batteries face challenges, such as the need for sophisticated battery management systems to prevent overheating and maintain optimal conditions. Choosing the right supplier is critical when selecting a lithium-ion based energy storage system. ACE’s battery energy storage systems utilize an intelligent three-stage battery management system and are UL 9450 certified for superior protection and optimal performance.
Lead-acid Battery
Lead-acid batteries are a mature technology typically used in applications where the number of battery cycles is infrequent, such as starting a vehicle or providing emergency backup power. They are reliable, economical, widely available and capable of delivering high power. However, compared to lithium-ion batteries, they have a lower energy density and a shorter service life, especially under deep cycle conditions. Regular maintenance is necessary to maintain performance, and improper recycling can harm the environment.
Lead Carbon Batteries
Lead-carbon batteries are a variant of lead-acid batteries that incorporate a carbon layer in the negative electrode to enhance performance. They combine lead-acid batteries’ high C-rate performance with carbon’s ultra-capacitive properties, allowing for rapid energy release or absorption. Adding carbon mitigates the negative effects of partial state-of-charge operation and extends cycle life compared to conventional lead-acid batteries. Carbon batteries are an affordable option for grid-scale energy storage systems because of their lower cost, satisfactory performance characteristics, and the fact that space is not an issue. However, carbon batteries still do not last as long as lithium-ion batteries. Like lead-acid batteries, carbon batteries have an environmental impact and must be handled carefully to prevent lead contamination. Despite their improved performance, carbon batteries still have a lower energy density than lithium-ion batteries.
Flow Batteries
Flow batteries (such as vanadium redox flow batteries) derive their charging capacity from two chemical components dissolved in a liquid within the system. They can store large amounts of energy and are insensitive to temperature changes. The energy capacity (Wh) can be easily increased by using larger electrolyte storage tanks due to their long service life. However, flow batteries are more complex and expensive to install and maintain than other types of batteries.
Vanadium Redox Flow Battery
Vanadium redox flow batteries are rechargeable batteries that utilize vanadium ions in different oxidation states for energy storage. This type of battery has a long service life and is highly scalable, making it popular for large-scale energy storage applications. However, vanadium’s rarity and price volatility can be problematic compared to more common technologies such as lithium-ion batteries.
Sodium-sulfur (NaS) batteries
Sodium-sulfur batteries can operate at high temperatures and can conduct deep daily cycling, making them suitable for grid storage applications. Because sodium-sulfur batteries operate at high temperatures, typically around 350°C, they require significant safety measures and thermal management systems. Due to their large size and complexity, sodium-sulfur batteries are more suited for large-scale applications (multi-megawatt-hour) than for small-scale commercial or residential use. Currently, sodium-sulfur batteries are not very popular in the market.
Solid State Battery
Solid-state batteries are an emerging technology that uses solid electrodes and solid electrolytes instead of the liquid electrolytes found in conventional batteries. Solid-state batteries are expected to have significantly higher energy density, improved safety due to the use of non-flammable solid electrolytes, and a longer lifespan. In addition, they are expected to reduce charging times. However, they are still in the early stages of development and are not yet commercially available on a large scale. The manufacturing process remains complex and costly.
Differences between solid-state batteries and traditional lithium-ion batteries
Each type of battery has its advantages and disadvantages. The best technology choice depends on the project’s specific needs, including factors such as cost, required capacity, discharge time and available physical space.
Commercial, Residential, and Utility-Scale Battery Energy Storage
Battery energy storage systems are widely used in the residential, commercial, and utility sectors, each with different needs, capacities, and applications.
Residential Battery Energy Storage
For a single home, residential battery energy storage systems typically have a capacity of between 5 and 15 kWh, which is enough to offset peak electricity usage or provide backup power in the event of a power outage. They are often paired with rooftop solar installations, allowing homeowners to store excess solar energy for use at night or on cloudy days. Residential battery storage systems can provide stored solar energy for a home or provide emergency backup power when needed.
Commercial Battery Energy Storage
Commercial energy storage systems have much larger capacities, ranging from 30 kWh to 2,000 kWh, and can be used in commercial, municipal, multi-unit residential or other commercial buildings. These systems can reduce energy costs by lowering demand charges, shifting high-electricity-price loads during peak hours to lower-price loads during off-peak hours, providing backup power, and participating in demand response programs. An example is Cohen’s 500 kW 500 kWh battery storage system, which, combined with on-site solar, intelligently manages energy use throughout the building, reducing peak demand and saving energy costs. For more information on optimal performance, check out our complete guide to optimal AGM battery performance.
Utility-Grade Battery Energy Storage
At the other end of the spectrum is utility-scale battery energy storage, which refers to batteries that store several megawatts (MW) of power, typically for grid applications. These large systems can provide services such as frequency regulation, voltage support, load balancing, and storage of excess renewable energy for later use. A well-known example is the Hornsdale Power Reserve in South Australia, a 150 MW/194 MWh installation that has brought stability to the region’s power grid and saved millions in costs.
Grid Maintenance Costs
Hornsdale’s Power Reserve battery energy storage unit exemplifies how battery energy storage systems can meet the needs of a wide range of users, from individual households to electric vehicle charging stations and even the national grid.
Forecasts indicate that battery energy storage units will grow significantly as new technologies and markets converge. One forecast shows that the installed capacity of grid-scale battery energy storage devices will increase 35-fold from 2022 to 2030, reaching nearly 970 gigawatts (GW). Given the enormous potential of battery energy storage systems to facilitate the integration of renewable energy sources and improve grid resilience, their importance is bound to grow, paving the way for a cleaner, more electrified future.