Carbon emissions of different fuels

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Approximate lifecycle carbon emissions of a number of different fuels for heating, transport and power

Fuels for heating and power

These represent figures for the carbon or carbon dioxide emitted by full combustion of each fuel, per unit of energy. Note that life cycle CO₂ emissions depend strongly upon details of supply chains, production techniques, forestry or agricultural practice, transport distances, etc.

Fuel	Net CV	Carbon content	Approx. life cycle CO₂ emissions (see note 1)		Annual total CO₂ emissions to heat a typical house (20 MWh p.a.)
Fuel	MJ/kg	%	kg/GJ	kg/MWh	kg	kg saved c.f. oil	kg saved c.f. gas
Hard coal	29	75	101	363	7,260	-2,060	-3,220
Oil	42	85	72	260	5,200	0	-1,160
Natural gas	38	75	56	202	4,040	1,160	0
LPG	46	82	72	230	5,600	600	-560
Electricity (UK grid – 2019)	–	–	54	193	3,860	1,340	180
Electricity (large scale woodchip combustion)	–	–	16	58	1,160	5,120	3,380
Electricity (large scale woodchip gasification)	–	–	7	25	500	5,780	4,040
Woodchips (25% MC) fuel only	14	37.5	2	7	140	6,140	4,400
Woodchips (25% MC) inc. boiler	14	37.5	5	18	360	5,920	4,180
Wood pellets (10% MC starting from dry wood waste) See note 3	17	45	4	15	300	5,980	4,240
Wood pellets (10% MC drying from gree wood using gas)	17	45	22	80	1,600	4,680	2,940
Wood pellets (10% MC) inc. boiler See note 3	17	45	7	26	520	5,760	4,020
Wood pellets (10% MC drying from gree wood using gas)inc. boiler	17	45	25	91	1,820	4,460	2,720
Grasses/straw (15% MC)	14.5	38	1.5 to 4	5.4 to 15	108 to 300	5,920 to 6,172	4,240 to 4,432

Notes:

Life cycle analysis data from: Carbon and energy balances for a range of biofuels options Elsayed, MA, Matthews, R, Mortimer, ND. Study for DTI URN 03/836, Greenhouse gas reporting – Conversion factors 2022, and: Comparison of energy systems using life cycle assessment A special report for the World Energy Council July 2000
Greenhouse gas reporting: Conversion Factors 2022 From the gov.uk website
These figures for wood pellets include the hammer mill and pelleting process, however do not include sourcing the feedstock and any pre-processing such as drying. If starting from green wood then drying could be a very major component, however pellets are often made from dry waste wood that has been dried for another purpose, such as joinery. These figures also do not include transport (which is included in the figures for wood chips).

Fuels for transport

Note that life cycle CO₂ emissions depend strongly upon details of supply chains, production techniques, forestry or agricultural practice, transport distances, etc.

Fuel	Net CV	Density	Energy density	Carbon content	CO₂ emission on combustion				Approx. life cycle GHG CO₂ eq. emissions				Land use implications
Fuel	MJ/kg	kg/m³	MJ/litre	%	g/litre	kg/gal	g/MJ	g/mile at 4.5 MJ/mile See note 1	g/litre	kg/gal	g/MJ	g/mile at 4.5 MJ/mile See note 1	miles/ha at 4.5 MJ/mile See note 1	miles/ha at 4.5 MJ/mile See note 1
Petrol (100% mineral)	44	730	32	87	2,329	10.6	72.5	326	2,340	10.6	73.1	329	–	–
Diesel (100% mineral)	42.8	830	36	86	2,617	11.9	73.7	332	2,700	12.3	75.0	338	–	–
LPG	46	510	24	82	1,533	7.0	65.4	294	1557	7.1	64.9	292	–	–
Bioenthanol (from sugar beet)	27	789	21	52	1,504	6.8	70.6	318	901	4.1	42.9	193	26,400	0.38
Bioethanol (from wheat)	27	789	21	52	1,504	6.8	70.6	318	168	0.76	8.0	36	13,800	0.72
Biodiesel (from rapeseed oil)	37	880	33	77	2,485	11.3	76.3	343	168	0.76	5.1	23	9,100	1.1
Biodiesel (from waste vegetable oil)	37	880	33	77	2,485	11.3	76.3	343	168	0.76	5.1	23	–	–

Notes:

4.5 MJ/mile is equivalent to 32.5 mpg for a petrol car or 36.4 mpg for a diesel car. However, this makes no allowance for differences in combustion efficiency between different engine designs. For example, diesel engines run at higher compression ratio than petrol engines and therefore are typically more efficient (fewer MJ per mile)
Life cycle analysis data from: Carbon and energy balances for a range of biofuels options Elsayed, MA, Matthews, R, Mortimer, ND. Study for DTI URN 03/836
To convert miles per gallon of a particular fuel to grammes of CO₂ per km divide the figure for g/litre of CO₂ (either directly from combustion or lifecycle) by the mpg figure multiplied by 0.354 (to convert to km/litre):
g/km = (g/l)/(mpg x 0.354) = (g/l x 2.825)/mpg

Including UK and international forestry in BEAT2

This report calculates the greenhouse gas emission savings (taking account of changes in forest carbon) resulting from using a range of forestry products (roundwood, wood chips and wood pellets) from UK and overseas forests to generate electricity.