Renewable energy is derived from resources that are replenished naturally on a human timescale. Such resources include biomass, geothermal heat, sunlight, water, and wind. All of these sources have their strengths and weaknesses. Some are more suited to certain locations than others, for instance. Some only produce electricity intermittently (when the sun is shining in the case of solar), though they can be paired with energy storage solutions to provide reliable electricity 24 hours a day throughout the year. Others, such as biomass, hydropower, and geothermal, can be used as baseload generation, producing a constant, predictable supply of electricity. None of these sources can meet all of our electricity needs effectively. But, together, they can completely displace fossil fuels without increasing the cost of electricity.