Solar energy can solve many energetic problems (to produce electric power with solar panels or, directly, hot water for domestic uses), but NOT ALONE. It must be used together its "sisters": WIND and GEOTHERMIC.

Infact, solar energy is diffuse and abundant, but not easy to concentrate, given that solar panels must cover wide land areas (easy to do it in deserts) to give a high energy contribution. Despite this, solar panels can be installed on the roofs of private or public buildings (houses, industries, hangars, docks, schools, hospitals,…)

Moreover, it can’t be used with efficience in polar and sub-polar regions, where solar light on Earth surface is scarce.

So, just here, is the WIND that can be employed, considering that these cold regions are very windy during all periods of the year. The only problems for eolic generators could be that of a certain manutention against freezing and mechanic stress in the rotating mechanisms, but it’s possible to remedy with a bit of organization.

The 3rd "sister" is GOTHERMIC energy. It exploits the natural heat of hot water or vapour underground sources, heated by volcanic phenomena (presence of magma) active near the water.

Water can be extracted, even by superficial rock layers, already in the vapour state under pressure, to feed some turbines generating electric power, but can also be introduced on purpose at the liquid state to reach the hot layers where it’s vapourized and can be used in the same way described above

Iceland is already producing the largest part of its own energy needs in this way, given to its higly volcanic nature with many hot water and vapour sources and it’s really a lucky case, but in many other parts of the world there’re volcanic "hot spots" available.

Furthermore, at few Km deep, Earth crust is EVERYWHERE hot enough to vaporize water and make move some turbines on the surface, if put into those dephts on purpose. So, this is another CLEAN energy source available for all Countries of the world

To these three "good sisters" I prefer not to add a fourth one, i.e., the energy generated by combustion of BIO-GAS from anaerobic fermentation of vegetal matter produced on purpose or as a waste, because releases CO2, a greenhouse effect gas, so that it’s NOT a very clean energy source.