Definitions of terms used
Understanding eFuels
This page explains key terms relating to eFuels, MtG and the assessment of greenhouse gas emissions. Specific product and environmental statements are put into context where they are used.
This page explains key terms relating to eFuels, MtG and the assessment of greenhouse gas emissions. Specific product and environmental statements are put into context where they are used.
What are eFuels and how do they differ from fossil fuels?
eFuels (electricity-based fuels) are synthetic fuels whose production is based on electrical energy. Hydrogen and a carbon source are required to produce carbon-containing eFuels. The suitability of a particular fuel for vehicles and infrastructure depends on its specification and the relevant manufacturer approvals.
Burning eFuels also produces CO₂. Carbon origin alone does not determine the overall climate impact. This requires an assessment of the specific supply chain over its life cycle.
eFuels (electricity-based fuels) are synthetic fuels whose production is based on electrical energy. Hydrogen and a carbon source are required to produce carbon-containing eFuels. The suitability of a particular fuel for vehicles and infrastructure depends on its specification and the relevant manufacturer approvals.
Burning eFuels also produces CO₂. Carbon origin alone does not determine the overall climate impact. This requires an assessment of the specific supply chain over its life cycle.
How are eFuels produced?
Power-to-liquid processes begin by using electrical energy to produce hydrogen. Further synthesis and processing steps can then yield liquid fuels.
At the planned GEF1 plant, methanol is the direct feedstock. It will be converted into synthetic petrol using methanol-to-gasoline (MtG) technology. Production of the methanol feedstock takes place in the upstream supply chain and forms part of the greenhouse gas assessment.
Power-to-liquid processes begin by using electrical energy to produce hydrogen. Further synthesis and processing steps can then yield liquid fuels.
At the planned GEF1 plant, methanol is the direct feedstock. It will be converted into synthetic petrol using methanol-to-gasoline (MtG) technology. Production of the methanol feedstock takes place in the upstream supply chain and forms part of the greenhouse gas assessment.
Carbon origin and greenhouse gas balance are not the same thing
Burning eFuels also produces CO₂. The difference lies in the origin of the carbon. Carbon origin alone, however, does not determine the overall climate impact. A life-cycle greenhouse gas assessment must also consider energy, feedstocks and intermediate products, production, transport and distribution, among other factors.
A C14 analysis concerns the carbon origin of the sample tested. It does not, on its own, demonstrate a percentage reduction in greenhouse gas emissions over the life cycle.
Burning eFuels also produces CO₂. The difference lies in the origin of the carbon. Carbon origin alone, however, does not determine the overall climate impact. A life-cycle greenhouse gas assessment must also consider energy, feedstocks and intermediate products, production, transport and distribution, among other factors.
A C14 analysis concerns the carbon origin of the sample tested. It does not, on its own, demonstrate a percentage reduction in greenhouse gas emissions over the life cycle.
Studies and modelled scenarios
The results of a life-cycle assessment apply to the specific products, system boundaries, reference values and scenario assumptions examined. A modelled scenario is not a statement about the actual greenhouse gas balance of a future GEF1 product.
Specific reduction percentages require the precise source passage, reference basis and assumptions of the study concerned.
The results of a life-cycle assessment apply to the specific products, system boundaries, reference values and scenario assumptions examined. A modelled scenario is not a statement about the actual greenhouse gas balance of a future GEF1 product.
Specific reduction percentages require the precise source passage, reference basis and assumptions of the study concerned.
Further reading: GHG Saving Potential of E-fuels
Read the original publication
This reference does not imply that individual study results apply to the planned GEF1 product.
Read the original publication
This reference does not imply that individual study results apply to the planned GEF1 product.
Ökobilanzen im Projekt reFuels – Kraftstoffe neu denken
Research report by Manuel Andresh, Andreas Patyk, Martina Haase, Olaf Toedter and Philipp Weber, Karlsruhe Institute of Technology, 2021.
Original publication at KIT, DOI: 10.5445/IR/1000141494
The publication is not product-specific evidence for future GEF1 production.
Research report by Manuel Andresh, Andreas Patyk, Martina Haase, Olaf Toedter and Philipp Weber, Karlsruhe Institute of Technology, 2021.
Original publication at KIT, DOI: 10.5445/IR/1000141494
The publication is not product-specific evidence for future GEF1 production.
What pollutant emissions do eFuels produce?
Pollutant emissions must be assessed for the specific fuel, vehicle or engine and the relevant test conditions. Individual measurements cannot be generalised to all synthetic fuels or the entire vehicle fleet.
Exhaust emissions such as nitrogen oxides and particulate matter must also be distinguished from the greenhouse gas balance over the entire life cycle.
Pollutant emissions must be assessed for the specific fuel, vehicle or engine and the relevant test conditions. Individual measurements cannot be generalised to all synthetic fuels or the entire vehicle fleet.
Exhaust emissions such as nitrogen oxides and particulate matter must also be distinguished from the greenhouse gas balance over the entire life cycle.
Consider vehicle tests separately
ADAC describes tests involving specific vehicles and fuels. These results relate to the respective test conditions and do not provide general evidence of the suitability or environmental impact of the future GEF1 product.
Read ADAC’s account of the vehicle tests
ADAC describes tests involving specific vehicles and fuels. These results relate to the respective test conditions and do not provide general evidence of the suitability or environmental impact of the future GEF1 product.
Read ADAC’s account of the vehicle tests
Frequently asked questions about the greenhouse gas balance of eFuels
What role does efficiency play?
Producing synthetic fuels involves several conversion steps and requires more electrical energy than using electricity directly. Applications, energy density, infrastructure and existing uses are also relevant to the assessment. The greenhouse gas balance additionally depends on the energy source and supply chain.
What role do transport and distribution play?
The resulting emissions are part of the life-cycle assessment. Transport routes, modes of transport, storage and distribution must be considered for the specific supply chain.
What role does electricity supply play?
The origin and greenhouse gas intensity of the energy used affect the overall balance. Specific supply and verification arrangements are required even where renewable electricity is planned.
What role does efficiency play?
Producing synthetic fuels involves several conversion steps and requires more electrical energy than using electricity directly. Applications, energy density, infrastructure and existing uses are also relevant to the assessment. The greenhouse gas balance additionally depends on the energy source and supply chain.
What role do transport and distribution play?
The resulting emissions are part of the life-cycle assessment. Transport routes, modes of transport, storage and distribution must be considered for the specific supply chain.
What role does electricity supply play?
The origin and greenhouse gas intensity of the energy used affect the overall balance. Specific supply and verification arrangements are required even where renewable electricity is planned.
Conclusion and outlook
Synthetic fuels must be assessed for specific applications and supply chains. Carbon origin, fuel quality, vehicle suitability, exhaust emissions and greenhouse gas balance are distinct matters for assessment. GEF1 is developing an MtG plant; statements about the future product must take account of its actual feedstocks, energy supply and production conditions.
Synthetic fuels must be assessed for specific applications and supply chains. Carbon origin, fuel quality, vehicle suitability, exhaust emissions and greenhouse gas balance are distinct matters for assessment. GEF1 is developing an MtG plant; statements about the future product must take account of its actual feedstocks, energy supply and production conditions.