What are grid-scale batteries?

Grid-scale batteries, also known as utility-scale batteries or Battery Energy Storage Systems (BESS), are a collection of individual smaller batteries housed within a single controlled, large-scale energy storage system.

They are designed to store electricity that can be accessed for use during periods of high demand or low generation and can be recharged by electricity from the grid during times of low demand or high generation.

The capacity of grid-scale batteries is typically measured in megawatt hours (MWh), which explains how long the battery can replace a specific amount of generated electricity per hour. Most modern grid-scale batteries have up to four hours of storage capacity at maximum output. For example, Nova Scotia Power plans to install three grid-scale battery projects in the near future. Each of the projects have a maximum of 50MW of output for 4 hours, or 200MWh of capacity. Alternatively, the battery could have an output of 25MW for 8 hours, to meet the utility’s needs on a particular day.

The most common grid-scale batteries used in Atlantic Canada are lithium-ion. The technologies and materials of lithium-ion batteries are favored for projects undertaken by entities such as Saint John Energy and Nova Scotia Power due to lithium-ion being the most affordable option for the size and capacity required.

Why grid-scale batteries?

As Atlantic Canada adds more renewable energy sources to the grid, such as wind and solar, there will be times when there is limited generation from sun or wind, but demand still exists. Grid-scale batteries have fast-response power (measured in seconds) to back up generation to ensure reliability. Grid-scale batteries have a faster response time than fuel-fired generators or even hydropower.

For example, at night, when no solar power is available, or when it is not windy enough for wind turbines to generate enough electricity, grid-scale batteries can provide that back-up energy source.

Similarly, grid-scale batteries can help utilities deploy energy during times of generation outages to improve grid-reliability.

Not only do grid-scale batteries help improve reliability, but they are helpful during peak demand, like on the coldest winter days and during severe weather events. Grid-scale batteries enable utilities to allow peak shaving by deploying electricity to reduce the need to burn expensive fossil fuels to generate electricity in the morning and early evening when demand is the highest.

What role will grid-scale batteries play in Atlantic Canada’s net-zero future?

Grid-scale batteries will be increasingly important to help utilities manage hourly and seasonal variations as the share of variable renewable electricity generation grows across Atlantic Canada. Grid-scale batteries will help operate the grid more efficiently, by providing flexibility for when and where energy is delivered.

There are two main challenges today with grid-scale batteries:

  1. Cost: The current grid-scale battery projects in Atlantic Canada have all been supported in-part by the federal government. Over time, the storage duration is expected to improve and the costs per MWh are expected decrease for these projects, to help make them an increasingly cost-effective alternative to fossil fuel-fired generation for back-up generation.
  2. Duration: Current BESS projects are limited by the short-during output of the batteries (commonly between 2 and 4 hours). Technology is developing for long-duration BESS, but there is not guarantee when they will be commercial available and cost-effective.

Overall, the more grid-scale batteries developed and commissioned will mean less demand on non-renewable energy sources and greater progress toward Atlantic Canada’s net-zero future.

Telsa Megapack at Saint John Energy