[Part 2 of 3]

As our essay this week explains, solar power faces no such constraint. The resources needed to produce solar cells and plant them on solar farms are silicon-rich sand, sunny places and human ingenuity, all three of which are abundant. Making cells also takes energy, but solar power is fast making that abundant, too. As for demand, it is both huge and elastic—if you make electricity cheaper, people will find uses for it. The result is that, in contrast to earlier energy sources, solar power has routinely become cheaper and will continue to do so.

Other constraints do exist. Given people’s proclivity for living outside daylight hours, solar power needs to be complemented with storage and supplemented by other technologies. Heavy industry and aviation and freight have been hard to electrify. Fortunately, these problems may be solved as batteries and fuels created by electrolysis gradually become cheaper.

Another worry is that the vast majority of the world’s solar panels, and almost all the purified silicon from which they are made, come from China. Its solar industry is highly competitive, heavily subsidised and is outstripping current demand—quite an achievement given all the solar capacity China is installing within its own borders. This means that Chinese capacity is big enough to keep the expansion going for years to come, even if some of the companies involved go to the wall and some investment dries up.

In the long run, a world in which more energy is generated without the oil and gas that come from unstable or unfriendly parts of the world will be more dependable. Still, although the Chinese Communist Party cannot rig the price of sunlight as OPEC tries to rig that of oil, the fact that a vital industry resides in a single hostile country is worrying.

It is a concern that America feels keenly, which is why it has put tariffs on Chinese solar equipment. However, because almost all the demand for solar panels still lies in the future, the rest of the world will have plenty of scope to get into the market. America’s adoption of solar energy could be frustrated by a pro-fossil-fuel Trump presidency, but only temporarily and painfully. It could equally be enhanced if America released pent up demand, by making it easier to install panels on homes and to join the grid—the country has a terawatt of new solar capacity waiting to be connected. Carbon prices would help, just as they did in the switch from coal to gas in the European Union.