E-fuels, short for electrofuels, are a class of synthetic fuels designed for use in conventional combustion-engine vehicles. Unlike traditional gasoline and diesel, which originate from petroleum, synthetic e-fuel are artificially created using renewable sources.
It’s important to distinguish e-fuels from other synthetic fuels like ethanol and biodiesel. Ethanol, derived from plant materials, is primarily used as a petrol additive to boost octane and reduce carbon monoxide emissions. Biodiesel, on the other hand, is produced from vegetable oils and animal fats. In contrast, e-fuels are generated by using electricity to combine hydrogen and carbon dioxide (CO2).
How is E-fuel Produced?
The production of e-fuel depends on whether the desired end product is in gaseous or liquid form:
- Gas E-fuels: Gas e-fuels include renewable hydrogen and e-methane, both of which can later be liquefied to produce liquid hydrogen (H2) and e-GNL (gas-to-liquids) respectively.
- Liquid E-fuels: Liquid e-fuels, such as e-methanol and e-crude (synthetic crude oil), serve as precursors for e-kerosene and e-diesel.
- Gas or Liquid Form: Synthetic ammonia can be produced in either gaseous or liquid form.
The production process for e-fuel varies depending on the desired form. Two primary processes are used: Power-to-Gas and Power-to-Liquid. These processes typically involve two to three phases. Initially, hydrogen (H2) is produced through water electrolysis using renewable electricity. This hydrogen is then combined with another molecule, such as carbon dioxide (CO2) for e-crude and synthetic methane/methanol, or nitrogen (N2) for synthetic ammonia. Synthetic crude oil requires additional refinement, similar to fossil oil, to produce synthetic kerosene or diesel.
E-methane, e-methanol, e-diesel, and e-kerosene are categorized as synthetic hydrocarbons, necessitating the inclusion of CO2 in their production processes. CO2 can be sourced directly from the atmosphere or obtained from industrial plants using fossil fuels. The choice of CO2 source impacts the environmental benefits, production cost, and lifecycle analysis of the synthetic fuel.
An alternative method for synthetic crude oil production is high-temperature H2O/CO2 co-electrolysis, which is a shorter process that eliminates the need for renewable hydrogen input at the beginning. While it enhances productivity and potentially reduces investment costs, this technology is less mature, with most initial production projects opting for hydrogen production via low-temperature electrolysis in their first phase.
Also See: What is Renewable Diesel Fuel?
What are the Pros and Cons of E-fuels?
Pros of E-fuels:
- Compatibility with Existing Vehicles: E-fuels can power standard cars, vans, and heavy goods vehicles (HGVs) without requiring modifications.
- Quick Refueling: Refilling vehicles with E-fuels is a rapid process, making it well-suited for long-distance vehicles like HGVs.
- Utilization of Existing Infrastructure: No need for new infrastructure; existing refineries, pipelines, fuel delivery trucks, and petrol stations can be utilized.
- Blendability: E-fuels can be seamlessly blended with fossil fuels at any desired ratio, akin to ethanol blending in unleaded petrol.
- CO2 Emission Reduction: Adoption of E-fuels can lead to significant reductions in CO2 emissions in the UK.
Cons of E-fuels:
- High Production Costs: E-fuels are currently expensive to produce, with estimates indicating a cost of about £37.24 per imperial gallon, but expectations for eventual cost reduction to approximately £6.30.
- Limited Production Scale: E-fuels are not currently manufactured in large quantities.
- Local Pollution Emission: Vehicles powered by E-fuels still emit harmful gases, contributing to local pollution.
- Energy Intensive: E-fuels are argued to require more energy, particularly during the production process, compared to electric cars on a per-mile basis.
Also Read: What is Refuse Derived Fuel (RDF)?
What are the Applications of E-fuels?
E-fuel applications are as follows:
- Heavy Mobility Emissions: About a quarter of global CO2 emissions originate from heavy mobility. E-fuels are vital, especially in maritime and air transport, where full electrification is challenging.
- Infrastructure Compatibility: E-fuels use existing infrastructure, competing with traditional fossil fuels and biofuels.
- Aviation E-kerosene: By 2070, e-kerosene is estimated to cover nearly 40% of aviation energy needs.
- Green Hydrogen and Synthetic Fuels: Promising projects involve green hydrogen and captured CO2 to produce cost-competitive e-fuels.
- Ongoing Projects: Initiatives worldwide are developing e-fuels, including synthetic methanol production for ships in the North Sea, such as the Port of Antwerp project.
Must Read: Is Propane a Fossil Fuel?