Evaluating the regional potential for emissions reduction using energy storage

Energy storage is an enabler of low carbon electricity generation, however several studies have shown that its use can cause a non-trivial increase in carbon emissions even if the storage has 100% round-trip efficiency. To understand the impact of storage operation and demand response on emissions, it is necessary to determine the marginal emissions factor (MEF) at the time the storage or demand response was operated. This paper presents statistical approaches to determining regional MEFs using data on regional electricity demand and generation by fuel type, with a simple power flow model used to determine consumption emissions by region. The technique is applied to the electricity system in Great Britain in 2018. It is found that the impact of storage varies widely by location and operating mode, with the greatest emissions reductions achieved when storage is used to reduce wind curtailment in areas which consume high levels of fossil fuel generation, and the greatest emissions increases occurring where storage is used for wind balancing in areas where wind is not curtailed. The difference between the highest emissions reduction and highest emissions increase is found to be significant, at 785 gCO2 per kWh that passes through storage.