The article by Tim Fox states that energy storage is required to deal with the inherent intermittency of renewable energy.
However his opening paragraph stating that storage of electrical energy would be a solution, suffers from two fundamental flaws. The first is that storage of electrical energy on the Megawatt scale has yet to be developed and may eventually turn out to be impractical. The second is that the fundamental aim of renewable installations is not the production of electricity: but the reduction in the amount of fossil fuel used to generate electricity.
This re-statement of the basic aim of renewable energy installations should lead to more thought being given to storing energy in a suitable form to provide mechanical power for electrical generation when called for.
This approach has the merit of using existing techniques - one of which (pumped hydro schemes) is mentioned in the article.
Unfortunately Fox then dismissed this option by stating that it needs “reservoirs and mountains in order to work”. Reservoirs – yes, but mountains – no: as a pressurised chamber (probably located underground) would produce the same effect as gravitational head.
Tom Robertson, Milton Abingdon, Oxon