The main direction of alternative energy is the search and use of alternative (non-traditional) energy sources. Sources of energy are naturally occurring substances and processes that allow a person to receive the energy necessary for existence. An alternative energy source is a renewable resource, it replaces traditional energy sources operating on oil, produced natural gas and coal, which, when burned, emit carbon dioxide into the atmosphere, which contributes to the growth of the greenhouse effect and global warming. The reason for the search for alternative sources of energy is the need to obtain it from renewable or practically inexhaustible natural resources and phenomena. Environmental friendliness and economy can also be taken into account.

• Heat pumps