Investment in renewable energy is increasing and we are close to the point where there will be times when the output from renewable sources is more than current usage of energy plus the capacity to store it. This surplus energy will go to waste unless it can be diverted to some other use.

The installed cost of renewable energy is about a tenth that of energy that can be supplied continuously.

I’ve read somewhere that a major limitation on the use of renewable energy is the lack of transmission capacity particularly at the local level. I suggest that this supports the idea off local usage

The idea is to set up a regime in which energy can be sold at the instantaneous cost of generation (the spot price). This will encourage users to develop methods of using ways of using intermittent sources of energy. Examples are:

• In tropical regions where there is excessive sunlight during the day, making it desirable to cook in the cool of the evening. The heat of the sun is stored during the day for use that evening. (ok, not particularly original, a good illustration of decentralised harvesting of energy). A tavern could use solar energy during the day to produce enough hydrogen for the evenings cooking instead of bottled gas.

• A plant for producing and refining metals by electrolysis located in the middle of a wind farm.

• A hydroelectric scheme with a minimal dam that produces energy seasonally only when the flow of water is sufficient. The energy is then used power an aluminium smelter locally. The cost of the smelter being idle is offset by avoiding the capital (and environmental) cost of a big reservoir.

• The HYBRIT steel making process being developed is Sweden in which hydrogen is used instead of coal. Hydrogen is generated by electrolysis using renewable energy, and enough stored in underground tanks to keep the plant going when there are lulls in the availability of energy. The UK has some of the best potential sources of tidal energy to produce the hydrogen. This would an elegant combination because the only enough hydrogen energy needs to be stored to keep the plant going for the predictable few hours while the tide turns.

The UK has not reached this point yet, but it might be worth setting up the legal, financial, and communications systems to encourage the necessary R&D