Researchers from the Siberian Federal University (SFU) and the University of Cadiz have ‘dramatically enhanced’ the efficiency of solar power plants through the use of titanium dioxide (TiO2) based nanofluids.

Electricity in solar power plants is produced by heating water, which gives off steam that drives an onsite turbine. The water is not directly heated by the sun, however; sunlight is first collected and used to heat a synthetic heat transfer fluid called therminol, which is used to heat the water. The teams from Siberia and Cadiz combined the therminol oil with nanofluids, fluids containing nanometre-sized particles called nanoparticles, in this case made from TiO2.

The study, titled ‘Dramatically enhanced thermal properties for TiO2-based nanofluids for being used as heat transfer fluids in concentrating solar power plants’, is scheduled to be released in Renewable Energy in April 2018. It reports that the nanofluid is ‘prepared with a eutectic mixture of diphenyl oxide and biphenyl with the addition of TiO2 nanoparticles and 1-octadecanethoil’ in order to improve the efficiency of the system.

The scientists added a range of concentrations of TiO2 to the nanofluid to find the ‘optimal composition’ of the liquid, before studying several of its characteristics: viscosity, density, heat transfer coefficient and isobaric specific heat, a measure of heat given off when pressure remains the same during a process. The latter two features are integral to generating electricity, as the former measures the efficiency with which the liquid conducts heat, and the latter details the amount of heat that can be released.

According to the study, the nanofluid with a TiO2 volume fraction of 2.44% was the optimal blend, ‘increasing the efficiency by up to 35.4% with regard to pure heat transfer fluid.’

Andrey Yasinskiy, a senior lecturer at SFU and one of the authors of the study, said: “The nanoliquid we’ve developed will help generate electrical energy in a more effective way.”

The report concludes that thermal conductivity increased by up to 25.8% and the isobaric heat of the system was raised by 52.7% when the optimal nanofluid was added to the therminol.

Advances such as these will only become more valuable over time; solar generation is projected to increase from 7% of the total US renewable generation in 2015 to around 36% by 2050.

“Naturally, we plan to implement it into industry-specific processes,” continued Yasinskiy.

His report concludes that ‘nanofluids based on TiO2 nanoparticles seem to be a promising alternative to HTFs (heat transfer fluids) in CSP (solar power) plants.’