The words “renewable alternative energies” are usually referred to any source of energy that can replace the fuel we use to produce energy without damaging the environment with high carbon dioxide emissions.
Renewable energies are generated from natural resources, like the sunlight, the wind, the rain, the tides, geothermal heat and brown energy.
Solar energy, for example, is a natural resource which is captured by means of solar panels. A solar panel is usually made up of silicon, that absorbs sunlight and transforms it into electrical energy. And the energy you get costs nothing and is renewable.
Also wind is a type of renewable energy that is of great use to us because of its kinetic energy. A windmill (=mulino a vento) emits no harmful gases as the wind blows its blades, which in turn power a generator, creating energy.
Another renewable energy is water. With the use of dams (=dighe) hydroelectricity is generated using the potential energy of the stored water.
Geothermal energy is another alternative energy source. ‘Geo’ means earth and ‘thermal’ means heat. Geo-thermal energy therefore comes from the internal heat of the earth. Heat is used to generate steam which in turn generates electricity.
Tides (=maree) are also a form of renewable energy. The tidal process uses the natural movement of the tides to fill reservoirs and utilizes the movement of water to create energy.
In recent years hydrogen has been used with success in the car industry. Hydrogen as fuel is eco-friendly and much safer than gasoline.
Bio-fuel refers to fuels obtained from plants or animals, like ethanol from plants, or methane from animal excrements. Ethanol is, in combination with gasoline, being widely used in automobile industry. “Brown energy” on the other hand is the polite word used to describe methods of capturing the methane gas naturally generated by animals. It’s probably a bit “smelly”, but it’s “natural”.
And, by the way, Ryder assures me that “anti-stink pills” have already been invented!