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Abstract Onsite production of gigawatt-scale wind- and solar-sourced hydrogen (H2) at industrial locations depends on the ability to store and deliver otherwise-curtailed H2 during times of power shortages. Thousands of tonnes of H2 will require storage in regions where subsurface storage is scarce, which may only be possible using liquid organic H2 carriers. We evaluate aboveground system with a focus on providing technical insights into toluene/methylcyclohexane (TOL/MCH) storage systems in locations suitable for gigawatt-scale wind- and solar-powered electrolyzer systems in the United States. Here we show that the levelized cost of storage, at a national median of US dollar $1.84/kg-H2 is spatially heterogeneous, causing minor impact on the cost of H2 supply in the Midwest, and significant impact in Central California and the Southeast. While TOL/MCH may be the cheapest aboveground bulk storage solution evaluated, upfront capital costs, modest energy efficiency, reliance on critical materials and pre-sulfided catalysts, and greenhouse gas emissions from heating are opportunities for further development.

The performance of two underexploited ternary oxides – Ba3Fe2O6 and Ba5Fe2O8 are investigated for carbon dioxide capture and chemical looping oxygen uncoupling. The ternary compound Ba3Fe2O6 was found to have a structure characterised by space group Pa3¯. Experimental results have shown that both Ba3Fe2O6 and Ba5Fe2O8 are capable of cyclically capturing CO2 at temperatures above 800 °C. Ba5Fe2O8 demonstrated superior CO2 capture performance compared to Ba3Fe2O6, with consistent gravimetric CO2 uptake capacities of 4.35 wt% and 13.39 wt% at 900 °C and 1000 °C, respectively, over 20 cycles. In comparison, Ba3Fe2O6 demonstrated high initial CO2 uptake capacities which deteriorated cyclically, with 20 cycle average capacities of 7.73 wt% and 11.99 wt% at 900 °C and 1000 °C, respectively. Ba3Fe2O6 also exhibits excellent recyclability and satisfactory chemical looping oxygen uncoupling (CLOU) activity over temperature swing cycles between 550 °C and 950 °C. In contrast, the strong affinity with CO2 makes Ba5Fe2O8 unsuitable for application in chemical looping oxygen uncoupling or chemical looping air separation, especially in the presence of substantial partial pressures of CO2.

Highly stable and active CeO2-ZrO2 metal oxide catalyst was synthesized via the combustion method and was further functionalized with sulphate (SO42-) groups. The morphology, surface functionalities, and composition of the metal oxide catalyst were determined by scanning electron microscopy, N2 adsorption and desorption measurement, X-ray diffraction, and Fourier transform infrared spectroscopy. The synthesized catalyst was used for esterification of glycerol with acetic acid. Effects of the process parameters including acetic acid to glycerol molar ratios (3-20), catalyst loadings (1-9 wt.%) and reaction temperatures (70–110°C) on the glycerol conversion and glycerol acetates selectivity were studied. Excellent catalytic activity was observed by using the sulphated metal oxide catalyst resulting in a glycerol conversion as high as 99.12%. The selectivity towards the di and triacetin (fuel additive) formed stood at 57.28% and 21.26% respectively. The reaction rate constants and activation energies were also estimated using a Quasi-Newton algorithm, namely Broyden’s method and Arrhenius equations at 80-110℃. The calculated values were in accordance with the experimental values which confirmed the model. Finally, the developed catalyst could be reused for three consecutive cycle without major loss of its activity. Overall, the findings presented here could be instrumental to drive future research and commercialization efforts directed toward biodiesel glycerol valorisation into fuel additives.