A novel method for forecasting electricity prices in a system with variable renewables and grid storage

In future UK energy scenarios with a high level of electrification, a large share of electricity is expected to be generated from renewable sources. To accommodate the variability of renewable generation, flexibility in the network is vital. An important flexibility option is grid scale electricity storage. A simulation is made of the electricity system with variable renewable generation, electricity storage and flexible high carbon generators, assumed to be gas CCGT, for various UK scenarios. The simulation uses historical hourly meteorology to drive models of demand and renewable variation, and the consequent input/output operation of storage and dispatchable generation to balance differences between demand and renewables. A marginal cost method is devised to calculate the storage, renewable and dispatching capacity and operational costs incurred in each hour. These cost structures can form a transparent economic base for informing market design and setting prices for use in energy system models. Results show that while marginal costs for renewable generation are relatively low, reliance on battery storage for backup particularly during peak periods can result in high electricity prices and without a significant increase in projected fossil fuel or carbon prices, traditional high carbon electricity generators will still be cheaper to operate. This work will be used to analyse the interaction between district heating with thermal energy storage and heat pumps, and the electricity system.