Missouri has an abundance of energy resources. Missouri is a source for fuels for heating, generating electrical energy and other forms of energy conversion processes. There are three main energy resources – renewable, fossil and nuclear. Renewable energy resources are naturally replenished including hydropower and biomass (plant fuels such as wood used for heating). Fossil energy resources include petroleum and coal turned into various fuel power and heating products. Nuclear energy resources are mainly used as fuel for fission-based power plants. Certain radioactive elements in the Earth can be classified as nuclear energy resources, too.