11. Nuclear Energy
Nuclear power stations make electricity without using fossil fuels. They don't put carbon dioxide into the air, but they produce dangerous radioactive waste. This waste is put underground or under the ocean, where it must stay for thousands of years before it's safe.
If there's an accident at a nuclear power station, dangerous radioactive waste can get into the air and travel a long way. In 1986 an accident happened in Chernobyl in Ukraine. People died and many more people were sick. About 336,000 people had to move away to new home. Scientists are working hard to make nuclear power stations safer.