While the classic energy sources become scarcer, the world’s leaders are trying to find alternative ones to compensate and eventually replace them as a part of green earth cleaning campaign. The finite character of oil, natural gas and coal is not the only problem, as pollution is getting worse all around the world and this causes big changes in the climate. So, taking these things into consideration, the new alternative sources of energy rose in public attention. The most known are: solar energy, wind power, wave power and tidal power.

Wind power has been used for thousands of years in propelling sailing boats and sailing ships. Until the discovery of other type of fuels, the wind was a very used resource on the sea. The water-pumping windmill was also an innovation that helped the Americans water their crops and develop farming when no other energy source was available. In the present, wind farms are present all over the world and cover up to 20% of the used energy in some countries. The largest part of wind power is produced in Europe and the United States of America, up to 80% of the whole.

Solar energy has also been used for a long time in history to generate energy, but the last century came with the technology to optimize it. In order to generate this type of energy, heat engines and photovoltaics are good tools, but the discovery of new ways to increase the efficiency of solar energy is limited only by man’s imagination. Solar energy is of two types: active and passive. The active one is based on the use of photovoltaics and other solar collectors, while passive solar energy is based on using special building materials with properties to use the solar energy in the most effective way.

Wave and tidal power are two different types of alternative energy sources, first being based on the movement of the waves and the second one on the steady ocean currents.

Both are relatively safe for the flora and fauna of the oceans and in the present, there are many wave farms and tidal power plants in the Atlantic and Pacific Oceans, many of them still in the experimental phase, but their number is increasing.In the long run, using these alternative energy sources will reduce the pollution; a closer effect to our time will be to have more power at our disposal for the population than with the finite resources. The power demands have increased rapidly in the last decades, as our technology is mainly based on energy.