Application of NiFe2O4 redox reactions for solar fuel production via thermochemical CO2 splitting process: Efficiency analysis

The development of solar thermochemical fuels from CO2 is an important step forward in creating a sustainable alternative to fossil fuels as this approach not only aids in combating climate change by recycling CO2, but it also provides a versatile and scalable solution for energy storage and transportation. Determination of the solar-to-fuel energy conversion efficiency (ηsolar−to−fuel) of a NiFe2O4/CO2 splitting (CDS) cycle using a thermodynamic model was the purpose of this study. The HSC Chemistry program was used to gather the thermodynamic data needed to solve the model equations. For all calculations, the reduction non-stoichiometry (δred) was taken to be equal to 0.1. One of the main objectives of the study was to investigate how the molar flow rate (n˙inert) of the inert sweep gas affected process parameters associated with the NiFe2O4/CDS cycle. The study found that increasing n˙inert from 10 to 50 mol/s had a substantial impact on thermal reduction temperature (Tred) compared to increasing n˙inert from 50 to 100 mol/s. While the energy penalty for heating NiFe2O4-δred from re-oxidation temperature (Toxd) to Tred dramatically lowered, the energy required to reduce NiFe2O4 increased marginally due to the surge in n˙inert. The use of gas-to-gas heat exchangers with a gas-to-gas heat recovery efficacy of 0.5 reduced the energy required to heat the inert sweep gas. All things considered, the increase in n˙inert from 10 to 100 mol/s helped to lower Tred by 175 K, but it also raised the amount of solar energy required to run the cycle by 73.76 kW. As a result, at n˙inert = 10 mol/s, the value of ηsolar−to−fuel peaked at 13.7 %, and then decreased to 10.1 % as a result of the increase in n˙inert up to 100 mol/s.