Currently, 4.1 GW of battery energy storage capacity is operating in Great Britain. This is made up of 141 individual battery units located throughout the country. The increasing geographic diversity of this fleet is beginning to reveal locational trends for batteries of operation and revenues.
Previously, we have examined how batteries in Scotland are used for constraint management in the Balancing Mechanism. This article will dive into how batteries across the whole system are used in the Balancing Mechanism with respect to transmission boundaries.
Transmission boundaries determine locational differences in operation
In Great Britain, Grid Supply Points (GSPs) are points where the transmission network connects to the distribution network. These are grouped into regions and are managed by different Distribution Network Operators (DNOs). These regions, known as GSP zones, can be used to identify the location of batteries.
Meanwhile, there are physical limits to the electricity that can flow over transmission lines from one region to another. Where these limits occur is known as a ‘boundary’. Boundaries can become constrained when the power wanting to flow through it is greater than its capacity.
Ultimately, transmission boundaries (and the constraints that can occur within them) drive most locational Balancing Mechanism dispatches and, therefore, better describe the impact of location on batteries than GSP zones.
The major transmission boundaries do not always follow GSP zone borders, and not all batteries within the same GSP zone are contained within the same transmission boundaries. For example, the EC5 boundary splits the Eastern GSP zone in two.
Battery energy storage is used very differently in the North and South
How a battery is used in the Balancing Mechanism can depend on what side of a boundary it is located. During times of generation constraint on the grid, batteries generation-side can be turned down with Bids. Batteries on the other side of these constraints can be turned up using Offers to balance overall energy on the system.
The effect this has on overall Balancing Mechanism dispatches is shown by the level of Bid and Offer dispatch volume in a particular region.