Table 1.

Basis of calculation for the energy requirements of H₂ SCP production. *To the best of our knowledge there is no source which states the exact calorie content of SCP produced from hydrogen, so we are taking it to be similar in this regard to SCP from methane, with a value of 22 MJ/kg based on the UniProtein methane SCP product.

Variable	Value	Unit	Source
CO₂ requirement	0.43	kg CO₂/kg SCP	(Sefton, 2018)
H₂ requirement	2.41	kg H₂/kg SCP	(Sefton, 2018)
Energy content of SCP	22	MJ/kg	(Unibio Group, 2020)*
Expected electrolyzer efficiency	70%		(Shiva Kumar and Himabindu, 2019)
Minimum energy required to produce hydrogen	39.4	kWh/kg H₂	(Züttel et al., 2011)
Gasification mass yield	0.202	kg H₂/kg coal	(Gnanapragasam et al., 2010)
Coal heating value	32.9	MJ/kg	(Gnanapragasam et al., 2010)
Solid content of dryer inlet	20%		(Sillman et al., 2019)
Energy consumption of spray dryer	4880	kJ/kg evaporated water	(Baker and McKenzie, 2005)
Electricity to thermal energy usage ratio of spray dryer	1:27	Electricity:thermal	(Baker and McKenzie, 2005)
DAC energy requirement	8.81	GJ/tonne CO₂ captured	(Keith et al., 2018)
Electricity to thermal energy usage ratio of DAC	17%	Electricity/thermal	(Sillman et al., 2019)
Energy use of fermentation step	1.6	kWh/kg SCP	(Pikaar et al., 2018)
Energy use of air separation	0.357	kWh/kg O2	(Aneke and Wang, 2015)