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.)|
|MJ/kg||%||kg/GJ||kg/MWh||kg||kg saved c.f. oil||kg saved c.f. gas|
|Electricity (UK grid - delivered)||-||-||164||590||11,800||-5,520||-7,260|
|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|
- 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 2016, and: Comparison of energy systems using life cycle assessment A special report for the World Energy Council July 2004
- 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 wod 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|
|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|
|LPG (mainly propane)||46||510||24||82||1,533||7.0||65.0||292||-||-||-||-||-||-|
|Bioenthanol (from sugar beet)||27||789||21||52||1,503||6.8||71.6||322||724||3.3||34||155||26,400||0.38|
|Bioethanol (from wheat)||27||789||21||52||1,503||6.8||71.6||322||511||2.3||24||109||13,800||0.72|
|Biodiesel (from rapeseed oil)||37||880||33||77||2,486||11.3||75.3||338||1,334||6.1||41||183||9,100||1.1|
|Biodiesel (from waste vegetable oil)||37||880||33||77||2,486||11.3||75.3||338||437||2.0||13||60||-||-|
- 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
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.