Electricity storage capacity requirements as a function of wind, solar, and nuclear penetration based on various studies modelling low-carbon generation scenarios in the GB power system.^9,–18 Panels give storage capacity in absolute (a and b) and relative (c and d) terms, considering power (a and c) and energy (b and d) capacity. Bulk generation capacity consists of wind, solar, nuclear, coal, gas (combined cycle), biomass, geothermal, waste, and wave. Dotted lines represent exponential fits to the complete data set. Shaded areas represent indicate respective uncertainty ranges excluding outliers. The formulas for exponential fits and uncertainty ranges are given.