Carbon emissions of different fuels

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
Hard coal 29 75 115 414 8,280 -2,000 -3,740
Oil 42  85 87 314 6,280 0 -1,740
Natural gas  38 75 63 227 4,540 1,740 0
LPG 46 82  72  259 5,180 1,100 -640
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

 

Notes:

  1. 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
  2. www.electricity-guide.org.uk/fuel-mix.html
  3. 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
Petrol 44 730 32 87 2,328 10.6 72.8 328 2,600 11.8 81 366 - -
Diesel 42.8 830 36 86 2,614 11.9 72.6 327 3,128 14.2 87 391 - -
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 - -

Notes:

  1. 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)
  2. 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
  3. 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.