RESUMO
Hydrogen (H2 ) produced from renewables will have a growing impact on the global energy dynamics towards sustainable and carbon-neutral standards. The share of green H2 is still too low to meet the net-zero target, while the demand for high-quality hydrogen continues to rise. These factors amplify the need for economically viable H2 generation technologies. The present article aims at evaluating the existing technologies for high-quality H2 production based on solar energy. Technologies such as water electrolysis, photoelectrochemical and solar thermochemical water splitting, liquid metal reactors and plasma conversion utilize solar power directly or indirectly (as carbon-neutral electrons) and are reviewed from the perspective of their current development level, technical limitations and future potential.
RESUMO
A mass spectrometer with a custom sampling system comprising one fixed and one variable orifice is presented. The custom sampling system allows the determination of the gas composition in the pressure range from 5 mbar to 1000 mbar, with low gas-demixing (<1.5%). A case study of mass spectrometer optimization and calibration for the measurement of relative concentration of CO2, CO, O2, and N2 gases is presented, together with an example of the CO2 conversion at a microwave plasma torch. The absolute error of the measured conversion of CO2 in CO is found to be less than 1.6% in the complete pressure range. The conversion determination routine presented here allows us to determine relative molar flows of CO2, CO, O2, and N2 and to distinguish between CO and N2 gases, which is important for the determination of the CO2 conversion in the case of air impurities or in the case of CO2/N2 mixtures.