Guide to Battery Energy Storage Systems

What is a Battery Energy Storage System?

Put simply, it is exactly as the name suggests, it is a Battery System which stores energy for various technical and commercial purposes.  In the case of Utility Scale batteries, they can be charged by a multitude of renewable sources or indeed by the grid.  The level to which they are charged or discharged depends primarily on the function the owner wants them to perform.  

Battery Energy Storage Systems (BESS) are becoming increasingly important for maintaining power stability, sustainability and cost-effectiveness as well as generating significant commercial returns for the asset owners.

Most modern Battery Energy Storage Systems can perform several grid functions, using the same battery asset at different times or the day or night.  For example, peak shaving, peak shifting, arbitrage and frequency regulation to name a few of the common ones, can all be performed by the same battery system.  The battery itself is one portion of the whole, but other equipment and intelligence must be added before it becomes a useful grid asset.  Associated equipment such as power conversion hardware, control logic and monitoring systems, all combine to enable the battery to act as an energy system and either accept or deliver energy when required by the end users.

One of the main benefits of a modern BESS is that it enables the addition of large amounts of renewable energy sources to be integrated into the existing power grid.  We all know the challenges presented by the intermittency of Solar and Wind power, but as <reported in our previous article> these are overcome or largely mitigated by adding utility scale batteries or other storage formats into the grid.  The excess energy produced during windy and sunny periods is stored and is then released during periods of high demand from the grid.  These functions help to smooth out demand fluctuations and improve the overall reliability of the power network.  Having a storage element integrated into the power grid also enables fast response times for charge and discharge to enable the frequency of the grid to be regulated which enhances overall grid stability.

▶  Balancing supply and demand – storing excess energy for release on demand.
▶  Integrating renewable energy sources – mitigates intermittency.
▶  Improving power grid stability – multiple grid functions serviced.
▶  Reducing greenhouse gas emissions – help fight climate change.
▶  Improving energy security – reduced dependency on fossil fuels.
▶  Cost effective – reducing costs helping drive uptake.

Types of Battery Energy Storage Systems (BESS)

Battery Energy Storage Systems vary in size and type, ranging from small residential systems to large utility scale systems.  There are systems presented in small cabinets for indoor residential use, all the way up to massive grid sites comprised of hundreds of 40 foot containers.  The All-New Elementa from Trina Storage is a modular, flexible and scalable system for utility applications and microgrids.

In commercial and industrial systems, BESS capacity usually range from several megawatt-hours (MWh) field, whilst utility scale systems can range from tens of MWh to hundreds of MWh or even more. These utility scale systems are typically used to support the stability of the power grid, by providing energy during peak demand periods and to store energy from renewable sources to be used later.

The battery chemistry deployed depends largely on the application to be serviced.  Here we have included some of the battery chemistries and storage solutions they provide.

Lithium-ion batteries

These are the most widely used types of batteries in modern battery energy storage systems.  They have a high energy density, long life, and low self-discharge rate, making them an attractive option for grid-scale energy storage. Lithium-ion phosphate (LFP) batteries are playing an essential role in the transition to renewable energies.

Lead-acid batteries

These batteries have been used for many years in battery systems.  They are relatively inexpensive compared to many other options. However, they have a relatively low energy density and shorter life compared to lithium-ion batteries.

Flow batteries

These batteries store energy in a liquid electrolyte, rather than in a solid state, and can be scaled up to large capacities.  They have a relatively long life and can be recharged and discharged many times, but they are more expensive than lithium-ion batteries.

Sodium-sulphur batteries

These batteries are used for high-temperature applications and have a relatively long life and high energy density. They are more expensive than lithium-ion batteries and have seen lower deployment rates.

Advanced chemistry batteries

This category includes batteries that use new and emerging technologies such as solid-state batteries, lithium-sulphur batteries, and lithium-air batteries.  They are still under development and although they great potential, their commercialization is not widespread as yet.

The current state of battery storage installations

According to a report by Wood Mackenzie (2022), Europe's grid-scale energy storage capacity will expand 20-fold by 2031. The European Commission set out a 'RePowerEU' plan which proposed a doubling of the share of variable renewables in power generation, passing 60% by 2030. Energy storage will play a crucial role in that rapid evolution, providing vital system flexibility to support power grid networks.

In 2022 alone, European grid-scale energy storage demand saw a tremendous 97% year-on-year growth, deploying 2.8GW/3.3GWh. This reflects energy storage's emergence as a mainstream power technology. Over the next decade, the top 10 markets in Europe will add 73 GWh of energy storage, amounting to 90% of new deployments.

Market share across Europe by key countries

The UK will retain its crown as the region's leading grid-scale storage market through to 2031, adding 1.5GW/1.8GWh in 2022 alone. The UK holds the largest storage project pipeline in Europe, with 25 projects above 100 MW.

In conclusion, it is clear from recent developments and future growth forecasts that battery energy storage will remain as an important component in the grid network jigsaw puzzle but also it's important to note that battery storage is just one of many mechanisms being deployed in our fightback against climate change. At Trina Storage, we're providing a flexible energy storage solution for utility-scale and commercial applications with vertical integration with renewable energy power.