Potential for domestic thermal storage to absorb excess renewable energy in a low carbon future

Transition to low carbon electricity generation is key to meet the global emission targets. This requires a drastic shift from the current energy mix dominated by coal and gas to renewables especially wind and solar. Due to the intermittent nature of renewable generation, the probability of generation-demand mismatch is high. This mandates the need for storage of the excess generation in order to prevent curtailment. Utilisation of domestic hot water tanks to absorb this excess provides us with an economical option at a nominal incremental cost. This paper develops a method to quantify the capacity of hot water tanks required and the potential savings in a low carbon future. The results are explained with the UK as a case study. The results indicate that between one and ten Terra Watt hours of curtailment can be expected in the UK in the year 2040. Eighty percent of this energy can be captured if one-fifth of all houses in the UK are equipped with smart hot water tanks.