Renewable energy played an important role in reducing greenhouse gas emissions. Non-biomass renewable sources such as hydropower, geothermal, wind, and solar do not have direct greenhouse gas emissions. However, renewable energy is more expensive to produce and use than fossil energy in general. This is because favorable renewable sources are usually located in isolated areas that can be costly to build power lines to connect it to cities that need electricity.
Furthermore, the availability of renewable source is not constant as electricity from solar power plant could be affected by clouds, electricity from wind farms by low wind, and the water availability for hydropower by drought.