Carbon Payback Assessment for Grid-Scale Battery Energy Storage

This work was undertaken when Below280 was part of Decerna.

General

Gigabox Developments Limited (Gigabox) is a UK developer of large-scale battery energy storage systems. Below280, operating as part of Decerna, produced two studies supporting Gigabox’s planning applications for a 50MW/100MWh grid-scale lithium-ion BESS facility. One established the carbon savings the battery would deliver in operation. The other assessed the carbon embodied in building it. Together they answer the question any planning authority or investor will eventually ask: does this facility actually reduce carbon, and when?

Outline & Objectives

We developed two detailed technical reports;

1. Carbon Impacts of Batteries quantified the year-one carbon savings delivered by the BESS on the UK electricity grid. Batteries reduce curtailment, the renewable electricity lost when generation exceeds demand. Quantifying that saving requires care about what the battery is actually displacing. Using standard BEIS grid carbon factors gives one figure. Modelling the real generation mix the battery would push off the system, primarily Open Cycle Gas Turbines, gives a more honest one. Below280 calculated both figures. The study also assessed carbon intensity against realistic grid balancing alternatives, including diesel generators and gas peaking plant, giving the planning case a comparative dimension.
2. Carbon Payment Time of Grid Scale Batteries applied the ISO 14040/44 framework to the materials within the system, from raw material extraction through to installation. The scope covered the full facility, not just the battery modules. Inverters, transformers, cabling, concrete plinths, shipping containers and balance-of-plant were all included. Below280 built an OpenLCA model against the Ecoinvent 3.7 database, developing bespoke background processes for LiFePO4 and LiPF6 where standard proxies fell short. The functional unit was 1 MWh of energy storage across the 100 MWh system.

The objective across both studies was a carbon narrative Gigabox could defend: the embodied footprint of the facility, which materials drive it, and how long operational savings take to cancel the upfront carbon debt.

Outcomes

The carbon impacts study found year-one savings of between 2,157 and 3,371 tonnes CO2eq. The higher figure, derived from OCGT displacement rather than average grid intensity, is equivalent to the non-heating electricity use of roughly 3,800 average UK homes.

Total embodied carbon came to 8,351 tonnes CO2eq for the 100 MWh system. Electronics, LiFePO4, and aluminium account for 34.3%, 22.9%, and 18.7% of that respectively, the material-level detail that tells a design team where intervention would actually move the needle.

Dividing embodied carbon by the annual operational saving gives a payback period of approximately 2.5 years. Gigabox left the process with a clear evidenced environmental position for planning and investor engagement, and a material-level baseline to build on as the project develops.