Geothermal is very promising for both power application (deep geothermal) and industrial applications (intermediate depth geothermal). Also, waste to energy is a viable renewable since humans will always produce waste and the best way to deal with waste is to reuse it and reduce it.
Hi Aya, thanks for your question. Indeed, besides solar, hydro and wind as renewable energy sources , there is biomass and geothermy. Biomass is the technology of using the energy within plants ( for example: the producion of woodpellet from peanut shell or rice husks , bioethanol produced from sugarcane is used as a fuel for cars ) . Biomass is also used to produce electricity. The other RE source is geothermal energy, which is different from solar thermal energy . The first is the fact of using energy from the heat ( through high temperature)and the second is using the energy from the sun to heat ( like solar water heater).
