One of the most important threats the mankind has to face is a global warming resulting from emissions of carbon dioxide
and methane to the atmosphere, which have been increasing since the technical revolution. 


The tragic result of global warming is the increase of sea and ocean levels which can cause floodings. Unprecedented ever before droughts and heat waves can cause the lack of water, fires and even the death of tens of thousands of people, as well as a decrease in population of some plants and animals (in some cases the temperature increase can cause a total extinction of some flora and fauna species, which will not be able to adapt to climate change). There is also a threat of diseases transmissible from mosquitoes, insects and rodents in regions, in which these diseases had not been reported previously.
 
Facing the above mentioned threats, surely already no one has any doubt that the sustainable energy, that is to say the solar, wind and sea wave energy should be commonly used. This is so called “clean energy”, which is environment friendly. A violent development of technology caused that devices powered by the sustainable energy are now on the commercial market and the offer of them to the client is constantly expanding; to these belong wind turbines, water power plants, solar cells, and solar collectors. 
 
Since each country is obliged to struggle for natural environment, the decrease in production costs and improvement of the efficiency of above mentioned devices is only the matter of short time perspective. Pro-ecological policy of highly developed countries creates favourable conditions to overcome of such inconveniences and to implement widely understand programmes aimed to make it easier to use the solar, wind and water energy. Often, these programmes are supported with different subsidies and grants.