Green energy is energy that produces little, if no, by-products that harm the environment. For example, fossil fuels like oil are expensive to mine, destructive to the environment during the actual drilling process and produce many toxic by-products that pollute our environment.
Solar, wind, and geothermal are types of green energy and they do not cause destruction to the environment either during their harvesting stage or as a by-product. When you use solar cells for example to store and create energy, you’re using energy directly from the sun. There’s no by-product and no waste created.