Some problems in storing renewable energy

Difficulties involved in some commonly advocated options for the storage of renewable electricity are discussed. As is generally recognised the most promising strategies involve biomass and pumped hydro storage, but these involve drawbacks that appear to be major limitations on the achievement of 100% renewable supply systems. Neglected aspects of the solar thermal storage solution are detailed, indicating that it is not likely to be able to make a significant contribution. Batteries, vehicle-to-grid, biomass and hydrogen based solutions also appear to have major drawbacks. Although other options not examined here might alter the outlook, the general impression arrived at is that the probability of achieving satisfactory storage provision enabling 100% renewable power supply are not promising. Provision of total energy supply from renewable sources would probably multiply the task by an order of magnitude.