The efficiency of cooling system is critical for wind turbines, particularly during the hot season, when high temperatures could damage the electric generator and mechanical parts of the turbine. The cooling system proposed in this paper is able to increase the efficiency of heat transfer with the use of nanofluids and the wind turbine tower as a heat exchanger to dissipate waste heat in the environment. In this study the use of Al2O3-water nanofluids has been considered. The results of this investigation appear encouraging because they have shown that the proposed new solution is able to assure highly efficient heat transfer and to limit thermal stresses on the electrical and mechanical components of wind turbines.

Fossil fuels are the most widely used resource for energy production. Carbon dioxide (CO₂) emissions are correlated with climate change, and therefore these emissions must be reduced in the future. It is possible by means of many different technologies, and one of the most promising seems to be oxyfuel combustion. This process, with oxygen and recirculating gas, produces a concentrated stream of CO₂ and water. In recent years, many scientists carried out research and studies on the oxyfuel process, but a sufficient level of knowledge was not yet reached to exploit the great potential of this new technology. Although such areas of research are still highly active, this work provides an overview and summary of the research undertaken, the state of development of the technology, and a comparison of different plants so far.