The Earth’s surface gets more energy from the sun in an hour than mankind consumes over a whole year. If we learnt how to exploit this resource, the energy problems we are facing would be solved.
Different techniques have already been developed. We can heat liquid that flows through dark piping beneath glass panes facing the sun. Today, 200 million Chinese people have solar water-heaters. We are also able to generate electricity with photovoltaic cells. Even though it is still unconventional, this is the world’s fastest-growing source of energy. There has been a 9-fold increase in production since 2000.
In concentrating solar thermal power plants, mirrors concentrate the sun which heats a fluid. It in turn powers a turbine and produces electricity. Theoretically, with this technology, 60 000 km2 of desert with strong sunshine would be enough to cover the whole world’s energy demand.
However, making power stations work is difficult; photoelectric cells only recover a small amount of radiation and building them pollutes and requires a lot of energy. Thus, solar energy only accounts for 0.039 % of world electricity consumption but this technology is developing rapidly. Some experts believe it will account for 25% of world consumption by 2040.
Either way, photoelectric cells have a real advantage: electricity can be produced locally, for those who are not connected to the grid. Today, 1.7 billion people live without electricity. Even in Western countries, local – or decentralized – energy production can be advantageous. Different resources (solar, wind and others) can be put together and energy losses and pollution caused by high tension networks can be avoided.