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Well-to-Tank Factors

The LowCVP assesses the impact of vehicles on a Well-to-Wheel basis. The reason for this is to ensure that both tailpipe emissions and the emissions associated with generating a fuel or energy vector are fully captured to enable a fair comparison of all technologies and fuels. e.g. an electric bus has no tailpipe emissions, but there are emissions produced in the generation and transmission of that electricity and so we must include the well-to-tank emissions to truly understand the greenhouse gas impact of that electric bus.

A Well-to-Tank emissions factor, also known as upstream or indirect emissions, is an average of all the GHG emissions released into the atmosphere from the production, processing and delivery of a fuel or energy vector.

To ensure a fair comparison of all technologies, the Low Emission Bus and Ultra-Low Emission Bus Schemes use the UK national carbon conversion factors that are produced annually by the Department for Business, Energy and Industrial Strategy. These factors are published annually and emission factors will vary depending on the origin, production process and feedstocks of various energy vectors and fuels.

The only fuel not to have a UK average factor is hydrogen (as there is no hydrogen grid) and so each operation will be assessed independently on a case by case basis. Hydrogen must be produced from renewable sources in order to have a strong case to reduce greenhouse gas emissions from transport operations.

LowCVP will publish the latest factors below as well as list the factors used on each LEB/ULEB certificate to ensure transparency and consistency. LowCVP will also aim to use these emission factors across all projects to enable fair comparison of greenhous gas performance of different vehicle types.

This page was last updated on 26th July 2019.

2019 Well-to-Tank Conversion Factors

 
Liquid Fuels
g CO2e/Litre
g CO2e/MJ
(Net CV)
% change from 2018- 2019
Pump Petrol (average biofuel blend)¹
598.52
18.52
- 0.1%
Pump Diesel (average biofuel blend)¹
617.09
17.20
- 0.2%
Bioethanol ¹
610.98
28.70
- 0.5%
Biodiesel (RTFO average)¹
367.95
11.08
+ 17.2%
Hydrogenated Vegetable Oil (HVO)²
980.87 28.58
n/a
Biodiesel (UCO)¹
264.77
8.00
-9.8%
Gaseous Fuels
g CO2e/ kg
g CO2e/MJ
(Net CV)
% change from 2018- 2019
CNG¹
488.0
11.89
- 4.5%
LNG¹
877.9
19.59
0%
LPG¹
369.3
8.04
0%
Biomethane (Compressed)²
643.16
13.13
+6.6%
Other
g CO2e/kWh
g CO2e/MJ
(Net CV)
% change from 2018- 2019
UK Grid Electricity¹
315.98
87.77
-10%
Hydrogen (Thermal)³
31.7- 854.3
8.8 - 237.3
-
Hydrogen (Electrolysis)³
15.1 - 1776.6
4.2 - 493.5
-
 
1 Figure has been sourced from DBEIS 'Government emission conversion factors for company greenhouse gas reporting' - conversion factors for 2019. Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2019
 
2 Figure has been sourced from the RTFO 2017/18 Year 10 - report 6. Available at: https://www.gov.uk/government/statistics/biofuel-statistics-year-10-2017-to-2018-report-6. 
 
3 Range sourced from JEC “Well-to-Tank Appendix 4 – Version 4a: Description, results and input data per pathway” from “Well-to-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context” (2014). Available at: http://iet.jrc.ec.europa.eu/about-jec/downloads
 

The UK Grid Electricity factor for 2019 is broken down in the table below:

Source
Emission Value
Unit
% change from 2017- 2018
Generation
255.56
g CO2e / kWh
-10%
Transmission & Distribution Losses (T&D)
21.70
g CO2e / kWh
-10%
WTT from Generation
35.65
g CO2e / kWh
-15%
WTT from T&D
3.03
g CO2e / kWh
-15%
Total emissions
315.98
g CO2e / kWh
-21%

 

2018 Well-to-Tank Conversion Factors

 
Liquid Fuels
g CO2e/Litre
(Net CV)
g CO2e/MJ
(Net CV)
% change from 2017- 2018
Pump Petrol (average biofuel blend)¹
596.65
18.51
+0%
Pump Diesel (average biofuel blend)¹
618.46
17.23
- 0.24%
Bioethanol ¹
613.77
28.83
- 5%
Biodiesel (RTFO average)¹
312.95
9.45
- 23%
Hydrogenated Vegetable Oil (HVO)²
980.87 28.58
n/a
Biodiesel (UCO)¹
293.60
8.87
-23%
Gaseous Fuels
g CO2e/ kg
(Net CV)
g CO2e/MJ
(Net CV)
% change from 2017- 2018
CNG¹
551.8
11.41
-6%
LNG¹
948.2
19.59
-2%
LPG¹
369.4
8.04
0%
Biomethane (Compressed)²
615.93
12.31
+23%
Other
g CO2e/kWh
(Net CV)
g CO2e/MJ
(Net CV)
% change from 2017- 2018
UK Grid Electricity¹
352.76
97.99
-21%
Hydrogen (Thermal)³
31.7- 854.3
8.8 - 237.3
-
Hydrogen (Electrolysis)³
15.1 - 1776.6
4.2 - 493.5
-
 
1 Figure has been sourced from DBEIS 'Government emission conversion factors for company greenhouse gas reporting' - conversion factors for 2018 energy (for energy supply 2016/17). Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2018
 
2 Figure has been sourced from the RTFO 2016/17 Year 9 - report 6. Available at: https://www.gov.uk/government/statistics/biofuel-statistics-year-9-2016-to-2017-report-6
 
3 Range sourced from JEC “Well-to-Tank Appendix 4 – Version 4a: Description, results and input data per pathway” from “Well-to-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context” (2014). Available at: http://iet.jrc.ec.europa.eu/about-jec/downloads
 

The UK Grid Electricity factor for 2019 is broken down in the table below:

Source
Emission Value
Unit
% change from 2017- 2018
Generation
283.07
g CO2e / kWh
-19%
Transmission & Distribution Losses (T&D)
24.13
g CO2e / kWh
-27%
WTT from Generation
41.98
g CO2e / kWh
-25%
WTT from T&D
3.58
g CO2e / kWh
-32%
Total emissions
352.76
g CO2e / kWh
-21%
 

2017 Conversion Factors

Liquid Fuels
g CO2e/Litre
(Net CV)
g CO2e/ MJ
(Net CV)
% change from 2016- 2017
Pump Petrol (average biofuel blend)¹
597.72
18.56
+30%
Pump Diesel (average biofuel blend)¹
619.77
17.27
+12%
Bioethanol ¹
645.35
30.65
- 6%
Biodiesel (RTFO average)¹
408.02
12.32
- 34%
Biodiesel (UCO)¹
382.69
11.56
- 34%
Gaseous Fuels
g CO2e/ kg
(Net CV)
g CO2e/ MJ
(Net CV)
% change from 2016- 2017
CNG¹
599.4
12.11
+10%
LNG¹
1006.7
19.59
-7%
LPG¹
369.7
8.04
0%
Biomethane (Compressed)²
615.93
10.00
0%
Other
g CO2e/ kWh
(Net CV)
g CO2e / MJ
(Net CV)
% change from 2016- 2017
UK Grid Electricity¹
445.72
123.5
-14%
Hydrogen (Thermal)³
31.7- 854.3
8.8 - 237.3
-
Hydrogen (Electrolysis)³
15.1 - 1776.6
4.2 - 493.5
-
1 Figure has been sourced from DBEIS 'Government emission conversion factors for company greenhouse gas reporting' - conversion factors for 2017 energy (for energy supply 2015/16). Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2017.
 
2 Figure has been sourced from the RTFO 2015/16 Year 8 - report 6. Available at: https://www.gov.uk/government/statistics/biofuel-statistics-year-8-2015-to-2016-report-6
 
3 Range sourced from JEC “Well-to-Tank Appendix 4 – Version 4a: Description, results and input data per pathway” from “Well-to-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context” (2014). Available at: http://iet.jrc.ec.europa.eu/about-jec/downloads

The UK Grid Electricity factor for 2017 is broken down in the table below:

Source
Emission Value
Unit
% change from 2016- 2017
Generation
351.56
g CO2e / kWh
-15%
Transmission & Distribution Losses (T&D)
32.87
g CO2e / kWh
-12%
WTT from Generation
56.05
g CO2e / kWh
-9%
WTT from T&D
5.2
g CO2e / kWh
-6%
Total emissions
445.72
g CO2e / kWh
-14%

2016 Conversion Factors

Liquid Fuels
g CO2e/Litre
(Net CV)
g CO2e/ MJ
(Net CV)
Pump Petrol (average biofuel blend)¹
461.3
14.32
Pump Diesel (average biofuel blend)¹
554.3
15.42
Bioethanol ¹
687.7
32.28
Biodiesel (RTFO average)¹
621.8
18.78
Biodiesel (UCO)¹
475.3
14.36
Gaseous Fuels
g CO2e/ kg
(Net CV)
g CO2e/ MJ
(Net CV)
CNG¹
543.8
11.37
LNG¹
1006.7
21.05
LPG¹
369.7
8.04
Compressed Biomethane Gas³
-2,205 - 725.2
-45.0 – 14.8
Liquefied Biomethane²
0.49
10.00
Other
g CO2e/ kWh
(Net CV)
g CO2e / MJ
(Net CV)
UK Grid Electricity¹
516.8†
143.5
Hydrogen (Thermal)³
31.7- 854.3
8.8 - 237.3
Hydrogen (Electrolysis)³
15.1 - 1776.6
4.2 - 493.5
 
Bus Operators intending to use compressed hydrogen should contact their fuel provider to determine the pathway used in producing and distributing the fuel to determine the appropriate WTT GHG emission factor. The ranges provided in the above table are indicative figures.
 
1 Figure has been sourced from DECC's UK greenhouse gas inventory - conversion factors for 2014/15 energy. Available at: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2016
 
The UK Grid Electricity factor for 2016 is explained in the table below:
 
Source
Emission Value
Unit
Generation
412.05
g CO2e / kWh
Transmission & Distribution Losses (T&D)
37.27
g CO2e / kWh
WTT from Generation
61.88
g CO2e / kWh
WTT from T&D
5.6
g CO2e / kWh
Total emissions
516.8
g CO2e / kWh
 
2 Figure has been sourced from the RTFO 2014/15 Year 7-report 6. Available at: https://www.gov.uk/government/statistics/biofuel-statistics-year-7-2014-to-2015-report-6
 
3 Range sourced from JEC “Well-to-Tank Appendix 4 – Version 4a: Description, results and input data per pathway” from “Well-to-Wheels Analysis of Future Automotive Fuels and Powertrains in the European Context” (2014). Available at: http://iet.jrc.ec.europa.eu/about-jec/downloads
 
*Liquefied Biomethane is produced by capturing biogas released from organic municipal waste disposed at landfill. Compressed Biomethane Gas is produced from biogenic waste e.g. animal slurry, using anaerobic digestion.