In one sentence, why not divert excess energy to generate and store hydrogen and derivatives for use as a winter fuel?
What is the point of e-cars when most of the energy presently has to come from fossil fuels! So, the overall efficiency of a fossil fuelled power station plus efficiency of the e-car propulsion system is likely to be less than a VW Golf Mk 7 Blue Motion for example. The only advantage that I can see for e-cars, is their zero emissions in cities but that is where the hybrid car can be used to advantage for both town and country. Prospects of the hydrogen powered vehicle seems to have gone cold, but all the windmills and freewheeling power stations at night could be generating hydrogen from electricity, thus powering a 'Hydrogen Economy'. Just imagine being almost freed from the 'shackles' of oil!!
Why not use the energy to generate hydrogen as the ultimate fuel. Alternatively sidrim848 has the same idea I had some time ago. Many homes could have a 2 ton weight in say a 15 foot hole for energy storage. I doubt the efficiency would exceed 30%.
I am very much in favour of wave and tidal power but not sure how well wave power will withstand raging winter storms.
But what about energy storage. Pumping water uphill as an energy store has been used with some success but how efficient is it? Why not generate hydrogen from electrical energy and allow that to be our energy store. Then we should be able to develop a hydrogen economy and power both domestic heating and transport using hydrogen fuel cell technology with the added bonus of freeing ourselves somewhat from the 'shackles' of oil and all it's political ramifications.
Sounds very exciting, but would like to see figures and/or graphs for energy conversion efficiency compared with photo-voltaic systems. Also projected comparative cost information would be appreciated.