Nowadays the effects of CO2 emissions are well known to human being. The world is in front of one of the biggest challenges ever faced. In 2020 CO2 concentration in atmosphere overcome 410 ppm causing an increase of 1°C of earth mean temperature. Despite the effort of many developing countries in reducing emissions, CO2 emissions reached in 2019 33.1 Gt, the historical highest value, due to the large reliance to fossil fuels of China, India and other South America countries. In these last decades any developing countries are trying to do better, especially Europe, with its ambitious plan to reach CO2 neutrality in 2050.