Division Typical and default values – biogas for electricity

United Kingdom

Biogas production system	Technological option		Typical value	Default value
Open storage of digestate accounts for additional emissions of methane which change with the weather, the substrate and the digestion efficiency. In these calculations the amounts are taken to be equal to 0,05 MJ CH₄/MJ biogas for manure, 0,035 MJ CH₄/MJ biogas for maize and 0,01 MJ CH₄/MJ biogas for biowaste.
Close storage means that the digestate resulting from the digestion process is stored in a gas tight tank and the additional biogas released during storage is considered to be recovered for production of additional electricity or biomethane.
Biogas production system	Technological option		Greenhouse gas emissions(g CO₂eq/MJ)	Greenhouse gas emissions(g CO₂eq/MJ)
Biogas for electricity from wet manure	Case 1	Open digestate^f1	– 28	3
	Case 1	Close digestate^f2	– 88	– 84
	Case 2	Open digestate	– 23	10
	Case 2	Close digestate	– 84	– 78
	Case 3	Open digestate	– 28	9
	Case 3	Close digestate	– 94	– 89
Biogas for electricity from maize whole plant	Case 1	Open digestate	38	47
	Case 1	Close digestate	24	28
	Case 2	Open digestate	43	54
	Case 2	Close digestate	29	35
	Case 3	Open digestate	47	59
	Case 3	Close digestate	32	38
Biogas for electricity from biowaste	Case 1	Open digestate	31	44
	Case 1	Close digestate	9	13
	Case 2	Open digestate	37	52
	Case 2	Close digestate	15	21
	Case 3	Open digestate	41	57
	Case 3	Close digestate	16	22

Annotations

f1: Open storage of digestate accounts for additional emissions of methane which change with the weather, the substrate and the digestion efficiency. In these calculations the amounts are taken to be equal to 0,05 MJ CH₄/MJ biogas for manure, 0,035 MJ CH₄/MJ biogas for maize and 0,01 MJ CH₄/MJ biogas for biowaste.
f2: Close storage means that the digestate resulting from the digestion process is stored in a gas tight tank and the additional biogas released during storage is considered to be recovered for production of additional electricity or biomethane.

f1: This group of materials includes agricultural residues with a low bulk density and it comprises materials such as straw bales, oat hulls, rice husks and sugar cane bagasse bales (not exhaustive list).
f2: The group of agricultural residues with higher bulk density includes materials such as corn cobs, nut shells, soybean hulls, palm kernel shells (not exhaustive list).