The most promising solutions to renewable energy’s spare power problem are the construction of a global solar power grid and the so called second-generation pumped storage hydropower (look at the other articles on these web-pages).

However, there is a large number of other, complementary answers to the problem.

Cold can be stored and heat can be stored. Power can be used to produce hydrogen, which can then be burned when needed, or converted to synthetic power-to-X fuels.

Batteries can provide part of the solution. The availability of lithium, copper, nickel and cobalt and the environmental damage caused by mining vast quantities low-grade ores will limit the possibilities of storing power in lithium batteries. However, it is also possible to manufacture high-quality sodium batteries, the main ingredients of which are sodium, sulphur, silicon and carbon. There is no practical upper limit for how much sodium batteries could be produced from these elements.

The Indian and Chinese electric vehicle and battery industries have already started to shift from lithium to sodium, and it is likely that the Vietnamese, South Korean, Japanese, US and European electric vehicle and battery industries will have to follow their lead, sooner or later. The lithium batteries we can produce from available raw materials should not be wasted to electric vehicles because they can also run with sodium batteries that can withstand a few hundred deep recharge cycles. Lithium batteries that can recharged up to 2 000 or even 4 000 times should be reserved for serving the grid. They are too valuable for electric vehicles: an electric car does not need a battery that can be reloaded 4 000 times because nothing else in the car around the battery will last for millions of kilometres.

Flywheels and ultra-capacitors can also provide complementing solutions. Germany is already constructing a flywheel-based power station that can provide up to 100 megawatts of spare power for the grid at a short notice. Ultra-capacitors can be discharged almost instantly.

An important solution to the problem is to adjust industries to the solar age. Innumerable different industrial processes can be redesigned so that they only consume huge amounts of electricity during the day, when the sun is shining and electricity is cheapest.

Adjusting the whole society to a solar economy would also bring with it huge public health benefits.  Solar economy will in any case reduce air pollution, but even otherwise we have evolved for being active during the day and less active in the night. All life on Earth has adjusted, during the last 3.6 billion years, to the 24-hour daily rhythm dictated by the sun. Our body is full of biological clocks operating according to these circadian rhythms and if we disrupt them, we are asking for trouble.

The amount of night-time lighting in Britain and in many other European countries has increased by 100 000 times during the last 300 years. According to numerous recent studies it seems that this excessive night-time lighting, which our minds and bodies have not been designed for, has greatly increased the incidence of cardiovascular disease, some types of cancer, diabetes 2, Parkinson’s disease, pathological obesity, insomnia and depression. These diseases, taken together, constitute most of the load of clearly premature mortality in the Western countries.

It seems that we would be healthier and happier, if we adjusted the society to the solar age, and produced less electricity during the night.