Modern energy is oil. If there is oil, there is light and heat. If there is no oil, then there is no light or heat.
Of course it is possible sometimes to use a wind-driven generator for a trifle purpose, or to warm up water in a swimming pool by the sun energy. But if it goes about serious power consumers such as megacities with the industrial enterprises, the only oil competitor is atomic energy. But even if the mankind overcomes fear of a new Chernobyl or Fukushima, even then it is difficult to find an alternative to oil products to substitute them in automobiles and particularly as airplane fuel. Approximately so a well educated contemporary person thinks, especially if he considers himself a cool pragmatic recognizing an absolute imperative of the market based on energy. What is surprising Jules Verne was the first to mention hydrogen as potential fuel and energy carrier in his novel «The Mysterious Island» in 1857.