c. A fuel switch for CCGT to hydrogen is being considered for decarbonisation of the power system. i. Assuming that a hydrogen CCGT has the same thermal efficiency (on a LHV basis) as a natural gas CCGT described in Q 1 a., how much hydrogen would be needed (kg/s) to produce 400 MW of power? ii. iii. iv. V. vi. Because of the low density of gaseous hydrogen, it may be necessary for hydrogen to be transported in liquid form (similar to LNG being used for transportation of natural gas). What is the saturation temperature (C) of hydrogen at 1 atmospheric pressure? Assuming an ambient temperature of 30C, estimate the maximum theoretical COP of a refrigeration system providing cooling between ambient and the saturation temperature of hydrogen found in part ii. above. In reality, liquefaction of hydrogen from a gas at ambient conditions does not require all the cooling to take place between the very low saturation temperature of hydrogen and the ambient temperature. Instead, this is only necessary for the condensation part of the process when the hydrogen is already at saturation temperature. Initially, the temperature of the (gaseous) hydrogen reduces progressively from ambient to its saturation temperature. Assuming that this results in an average cooling temperature for the liquefaction process of - 190C, re-do the calculations for maximum theoretical COP. Using the "improved" theoretical COP estimated in part iv., estimate the minimum work input (kJ/kg) to liquefy hydrogen, and the minimum theoretical power consumption (in MW) to cool/liquefy hydrogen needed to power a 400 MW power plant. You may assume that the cooling (kJ/kg) required is the difference in enthalpy of gaseous hydrogen at 30C/ 1 atm and saturated liquid hydrogen at 1 atm, and the amount of hydrogen needed is from the answer to part i. of the question. How do the results above compare to the estimated power required for liquefaction of hydrogen provided by the US Department of Energy in https://www.hydrogen.energy.gov/pdfs/9013 energy requirements for hydrogen gas com pression.pdf? vii. The analysis above (Q1 c) indicate a potential inefficiency in the use of hydrogen as an energy