More energy arrives at the Earth's surface in one hour than man uses in one year. This clean, natural energy comes from sunlight and it's called solar power. The question is... how can we use it to replace fossil fuels and nuclear energy? There are three answers:
We can use it directly.
Many modern buildings have big windows which face south. These collect solar power directly. In fact some buildings in North America and Scandinavia get 100% of their energy from the sun.
We can collect it on Earth.
Another way to collect the sun's power is with solar panels. These absorb and store energy on sunny days. But there are two problems with solar panels on Earth:
(a) They're expensive (b) They don't work very well on cloudy days.
We can collect it in space.
One answer to the problems of clouds is to collect solar power in space. The idea is expensive, but simple. Satellites with huge solar panels collect the sun's energy. Then they send it back to Earth. A series of satellites like this will be able to work for 24 hours a day.