In a single hour, the sun transmits more energy to the Earth’s surface than humans consume in a whole year. If we could find a way of harnessing this resource effectively, we could solve all of our energy problems.
Different solar power technologies already exist. Solar water heaters operate by heating up water in dark-coloured boxes or tanks covered with a plate pointed towards the sun. Today, 200 million Chinese people have solar water heating systems.
Photovoltaic cells generate electricity from the sun’s rays. While still relatively marginal, solar power is the fastest-growing energy in the world. Production has increased nine-fold since 2000.
The latest way of harnessing solar energy is via solar power plants. Mirrors concentrate the sun’s rays to heat a fluid; this in turn drives a turbine to produce electricity. In theory, with this technology 25,000 square miles (60,000 square kilometers) of desert could meet the entire world’s electricity demands.
However, solar power plants are relatively inefficient: photovoltaic cells can only convert small amounts of sunshine, while producing them itself requires a lot of energy and creates pollution. Solar energy thus only represents 0.039% of global electricity consumption. But technology is evolving rapidly and some experts predict solar power will attain 25%of global consumption by 2040.
Photovoltaic cells do have one huge advantage: they can produce electricity independently of a grid. Today, 1.7 billion people live without an electricity supply. Even in the West, the production of energy off the grid—decentralized production—can have benefits. It enables different sources of energy (solar, wind, etc.) to be combined, avoiding wastage and other problems associated with high-tension electricity networks.