The greenhouse gas emissions performance of cellulosic ethanol supply chains in Europe

Table 4 Cellulase manufacture assumptions

Process assumptions			Emission assumptions
Inputs and parameters	Unit	Quantity^a	kgCO₂e.kg protein^-1
Fermentor volume	m³	1000
Active volume	%	80%
Cellulase productivity	FPU.l^-1.h^-1	75
Cellulase activity	FPU.g protein^-1	600
Residence time	h	160
Agitation power requirement	W.m^-3	400
Air sparge power requirement^e	W.m^-3	2183
Biomass feedstock composition: cellulose/lignin	% (dry basis)	43%/28%
Initial cellulose concentration	%	4%
(NH₄)2SO₄	g.l^-1	1.4	1.17^b
KH₂PO₄	g.l^-1	2	1.11^b
MgSO₄.7H₂O	g.l^-1	0.3	0.56^b
CaCl₂.2H₂O	g.l^-1	0.4	0.56^b
Tween 80	g.l^-1	0.2	0^c
Corn oil anti foam	vol.vol^-1	0.001	3.51^d

^aNREL 1999 design report [14]; ^bestimated from GREET [31]; ^cassumed to be negligible; ^dassumed to be the same as rapeseed oil: LCAfood database [32]; ^eassumes air sparge rate: 0.577 v.v^-1.min^-1; compressor capacity:630.6 m³.min^-1; motor power: 2983 kW.

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