Alternative fuels are those fuels or power sources which serve, at least partly, as a substitute for fossil oil sources in the transport sector. According to the European Commission’s 2050 Long-term Climate Strategy, there is no single fuel solution for the future of low-emission mobility - all main alternative fuel options are likely to be required, but to a different extent in each of the transport modes.
Definitions
Current Directive on the deployment of alternative fuels infrastructure
Based on the Directive 2014/94/EU of the European Parliament and of the Council of 22 October 2014 on the deployment of alternative fuels infrastructure, the current definition applies:
“Alternative fuels” means fuels or power sources that serve, at least partly, as a substitute for fossil oil sources in the energy supply to transport and which have the potential to contribute to its decarbonisation and enhance the environmental performance of the transport sector.
Proposed Regulation on the deployment of alternative fuels infrastructure
According to the Proposal for a REGULATION OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on the deployment of alternative fuels infrastructure, and repealing Directive 2014/94/EU of the European Parliament and of the Council (COM/2021/559 final), “alternative fuels” (AF) means fuels or power sources which serve, at least partly, as a substitute for fossil oil sources in the energy supply to transport and which have the potential to contribute to its decarbonisation and enhance the environmental performance of the transport sector.
Scope
Current Directive on the deployment of alternative fuels infrastructure
The current AFI directive recognises six types of alternative fuels:
- Electricity,
- Hydrogen,
- Biofuels,
- Synthetic and paraffinic fuels,
- Natural gas, including biomethane, in gaseous form (compressed natural gas (CNG)),
- Liquefied Natural gas (liquefied natural gas (LNG)),
- Liquefied petroleum gas (LPG).
Proposed Regulation on the deployment of alternative fuels infrastructure
In the proposed AFI regulation, alternative fuels are classified in three distinct categories (which will be described in the remainder of this section):
| Categories | AF types |
|---|---|
| Alternative fossil fuels for a transitional phase | natural gas, in gaseous form (compressed natural gas (CNG)) and liquefied form (liquefied natural gas (LNG)) liquefied petroleum gas (LPG) synthetic and paraffinic fuels produced from non-renewable energy |
| Alternative fuels for zero-emission vehicles | Electricity Hydrogen Ammonia |
| Renewable fuels | ‘biomass fuels’, meaning gaseous and solid fuels produced from biomass ‘biofuels’ meaning liquid fuel for transport produced from biomass |
Alternative fuels for zero-emission vehicles
Electricity
Electricity is considered an alternative fuel under the European alternative fuels strategy and the new proposed regulation on the deployment of alternative fuels infrastructure. Electricity can be produced from three main sources: (1) fossil carbon, (2) nuclear and (3) renewable. In the EU in 2019, 39 % of the electricity consumed came from power stations burning fossil fuels and 35 % from renewable energy sources, while 26 % came from nuclear power plants. Among the renewable energy sources, the highest share of electricity consumed came from wind turbines (13 %), hydropower plants (12 %), biofuels (6 %) and solar power (4 %).
- Road
Electric vehicles (EVs), using a highly efficient electric motor for propulsion, can be supplied by electricity from the grid, coming increasingly from low-CO2 energy sources. Flexible recharging of vehicle batteries, at times of little demand or ample supply, supports the integration of renewable energy into the power system. EVs emit no pollutants and no noise and are therefore particularly suited for urban areas. Plug-in Electric Vehicles (PEVs) are the common terminology for plug-in hybrid electric vehicles (PHEV) and 100 % electric vehicles (Battery Electric Vehicles – BEVs). These vehicles are capable of drawing electricity from off-board electrical power sources and storing the energy in batteries. Hybrid configurations, combining internal combustion engines and electric motors, can save oil and reduce CO2 emissions by improving the overall energy efficiency of propulsion (up to 20 %) but are, without external recharging possibilities, not an alternative fuel technology.
The technology of EVs is maturing, and their deployment is picking up. By 2030, the European Commission wants to place at least 30 million zero-emission cars and 80 000 clean-energy lorries on Europe's roads. The key issues are excessive cost, low-energy density and heavy weight of batteries. These limit the driving range of vehicles. Normal recharging takes several hours. Fast, inductive recharging or battery swapping can alleviate the problem. Improvements in battery technology are essential for the market take-up of EVs. Electric two-wheelers share all the assets of EVs and can support their broad market penetration.
Lack of recharging points, with a common plug, is a major obstacle to market uptake. They would need to be located at home, at the workplace and in public spaces. At present, most of the Member States are catching up with the number of publicly accessible recharging points and announced policies to develop an adequate network of recharging facilities.
EVs can also be used for electricity storage and grid stabilisation and, to allow for a flexible electricity pricing system based on demand/supply, controlled interaction with the electricity network will be needed.
- Rail
Electric trains do not need to carry any internal combustion engine or large batteries, which makes them an ideal option, considering their excellent power-to-weight ratio.
- Aviation
Battery electric aircrafts are rapidly growing in terms of technology and market development. Energy density is widely recognised to be the bottleneck for the zero-emission electric powertrains. With growing efficiency rates, Li-ion batteries became adequate in 2019 for small aircraft. These vehicles are mostly used for short distances in smaller airports and flight schools.
- Maritime & inland waterways
Electricity can also supply clean power to waterborne transport. Shore-side electricity use by ships berthed at ports has been recommended where air quality or noise limits are exceeded.
Hydrogen
Hydrogen (H2) is a promising alternative fuel option for transport, where electrification is more difficult. In the first phase, early adoption of hydrogen can occur in captive uses, such as local city buses, commercial fleets (e.g. taxis) or specific parts of the rail network, where electrification is not feasible. Hydrogen refuelling stations can easily be supplied by regional or local electrolysers, but their deployment needs a clear analysis of fleet demand and different requirements for light- and heavy-duty fuel cell electric vehicles (FCEV).
- Road
Hydrogen fuel cells are important technology alternatives for heavy-duty road vehicles, alongside electrification, including coaches, special purpose vehicles, and long-haul road freight given their high CO2 emissions. The 2025 and 2030 targets set out in the CO2 Emission Standards Regulation are an important driver to create a lead market for hydrogen solutions, once fuel cell technology is sufficiently mature and cost-effective. Projects of the Horizon 2020 Fuel Cells and Hydrogen Joint Undertaking (FCH-JU) are aiming to accelerate Europe’s technological lead.
Hydrogen fuel-cell trains could be developed for other viable train commercial routes that are difficult or not cost-effective to electrify: about 46 % of the mainline network is still being served by diesel technology today. Certain fuel-cell hydrogen train applications (e.g. multiple units) can already be cost-competitive with diesel today.
- Maritime & inland waterways
For inland waterways and short-sea shipping, hydrogen can become an alternative low emission fuel, especially since the Green Deal emphasises that CO2 emission in the maritime sector must have a price. Scaling up fuel cell power from one to multiple megawatts and using renewable hydrogen to produce synthetic fuels, methanol, or ammonia - with higher energy density – are required for longer-distance and deep-sea shipping.
- Aviation
Hydrogen can become in the longer term an option to decarbonise the aviation sector, through the production of liquid synthetic kerosene or other synthetic fuels. These are “drop-in” fuels that can be used with existing aircraft technology, but implications in terms of energy efficiency must be considered. In the longer term, hydrogen-powered fuel cells, requiring adapted aircraft design, or hydrogen-based jet engines may also constitute an option for aviation.
The Commission will address the use of hydrogen in the transport sector in the upcoming Sustainable and Smart Mobility Strategy, announced in the European Green Deal and due to be presented before the end of 2020.
The key limiting factor for the use of hydrogen in industrial applications and transport is often the higher costs, including additional investments into hydrogen-based equipment, storage, and bunkering facilities. Furthermore, the potential impact of supply chain risks and market uncertainty is amplified by the tight margins for final industrial products due to international competition.
Demand-side support policies will therefore be needed. The Commission will consider assorted options for incentives at EU level, including the possibility of minimum shares or quotas of renewable hydrogen or its derivatives in specific end-use sectors (for instance certain industries such as the chemical sector, or transport applications), allowing demand to be driven in a targeted way. In this context, the concept of virtual blending could be explored.
Ammonia
Ammonia is a molecule with the chemical formula NH3 that occurs as a gas at room temperature and normal pressure. It can also be stored as a liquid at low temperatures (below -33 °C) and/or when compressed. In this case, it is called liquid ammonia.
The use of ammonia as a fuel is not recent. It has been used since the beginning of the 19th century as a fuel in motorised vehicles, in locomotives (England) or in tramways (New Orleans, US). During the Second World War, Belgium (then a victim of an embargo on diesel) even decided to power its buses with liquid ammonia. In the 1960s, ammonia was also considered for use in alternative engines, especially for military purposes. Ammonia was used as a propellant for some rocket planes in the 1950s and 1960s in a series of suborbital missions.
More recently, ammonia has come back to the forefront to decarbonise various specific sectors, the maritime transport sector as a replacement for certain heavy fuels (e.g. heavy fuel oil (HFO)), known for their greenhouse gas emissions. Ammonia is less risky than hydrogen during storage operations and emits less greenhouse gases than liquid petroleum gas (LPG) or compressed natural gas (CNG). It is therefore considered an economically viable fuel for the maritime transport sector. However, its overall environmental impact (from production to use) must be assessed on a case-by-case basis. Indeed, the transport of ammonia from its production area to port areas must be as short as possible (in terms of distance). Various initiatives to demonstrate the potential of ammonia in the maritime sector are gradually being set up, particularly in the Netherlands.
The efficiency of ammonia in internal combustion engines is improved when it is blended with other fuels. Ammonia has a low flame speed and high resistance to self-ignition. Doping ammonia with other fossil fuels (especially diesel) is the most technically efficient option, reducing CO2 and NOx emissions if the NH3 content of the blend does not exceed 60 % by weight. Gasoline/NH3 or ethanol/NH3 blends also offer high power output under stable conditions, although conditioned by NOx emissions during the combustion phases.
Liquefied petroleum gas (LPG)
LPG is a by-product of the hydrocarbon fuel chain. Its use in transport increases resource efficiency. LPG is an immediately available low-carbon alternative. Indeed, it emits 35 % less CO2 than coal and 12 % less than oil. It also emits almost no black carbon, the second biggest contributor to global warming. LPG offers significant environmental advantages, particularly in terms of indoor and outdoor air quality. It is characterised by low particle emissions, low nitrogen oxide (NOx) emissions and low sulfur content.
Currently, it is derived from crude oil and natural gas, and in the future also from biomass. Currently, gas (natural gas as well as LPG) is being flared in huge quantity. LPG infrastructure is well established, with some 32 000 dispensing sites in the EU but with a very uneven distribution across the Member States. Its advantage of producing low pollutant emissions, however, has been diminishing as the EURO standards have progressed to lower general emission limits. There remains, however, a clear advantage in lower particulate emissions. LPG might still expand its market share but will remain a niche market.
Automotive LPG, also known as autogas, is Europe's most widely used alternative fuel, with little need for investment in infrastructure. With over 15 000 000 vehicles already running on autogas, serviced by a filling station network of over 46 000 sites, Autogas offers Europe's drivers an alternative to conventional fuels.
Renewable fuels
Biofuels
Biodiesel is a renewable, biodegradable fuel manufactured domestically from vegetable oils, animal fats, or recycled restaurant grease.
Biofuels are currently the most important type of alternative fuels, accounting for 4.4 % in EU transport. Total biofuel consumption was 17.0 Mtoe in 2018. They can contribute to a substantial reduction in overall CO2 emissions, if they are produced sustainably and do not cause indirect land use change. They could provide clean power to all modes of transport. However, supply constraints and sustainability considerations may limit their use.
Biofuels can be produced from a wide range of feedstock through technologies in constant evolution and used directly or blended with conventional fossil fuels. They include bioethanol, biomethanol and higher bioalcohols, biodiesel (fatty-acid methyl ester, FAME), pure vegetable oils, hydrotreated vegetable oils, dimethyl ether (DME), and organic compounds.
First generation biofuels are based on food crops and animal fats. They include biodiesel and bioethanol. To mitigate against impacts of some biofuels, the Commission has proposed to limit the number of first-generation biofuels that can be counted towards the Renewable Energy Directive targets to 5 % and increased the incentives for advanced biofuels such as those made from lignocellulosic biomass, residues, waste, and other non-food biomass, including algae and microorganisms.
Liquid biofuels commercially available today are mainly ‘first generation’ biofuels. Blends with conventional fossil fuels are compatible with the existing fuel infrastructure, and most vehicles and vessels are compatible with the blends currently available (E10 – petrol with up to 10 % bioethanol and diesel with up to 7 % FAME biodiesel content). Higher blends may require minor adaptations of power trains, and corresponding fuel standards need to be developed. High-level petrol-ethanol blend containing 85 % ethanol (E85) is used in only a few Member States in flexible fuel vehicles (FFVs) that can also use lower blends.
Consumer acceptance of biofuels has been hampered by the lack of coordinated action across Member States when introducing new fuel blends, the lack of common technical specifications, and the lack of information on the compatibility of new fuels with vehicles.
Some biofuels such as hydro-treated vegetable oils can be blended at any ratio with conventional fuels and are fully compatible with existing refuelling infrastructure and road vehicles, vessels, locomotives, and planes for up to 50 % blends.
Biofuels in the transport sector are consumed in France, Germany, Sweden, Spain, Italy, and the UK, with a large gap between their consumption and that of the rest of the Member States.
For aviation, advanced biofuels are the only low-CO2 option for substituting kerosene. The compatibility of bio-kerosene with today's planes has been proven. Cost, however, must become competitive. The 'Flightpath 2050' initiative aims at 75 % reduction in CO2 emissions and 90 % reduction in nitrogen oxide (NOx) emissions.
Alternative fossil fuels for a transitional phase
Liquefied natural gas (LNG)
Natural gas in liquefied form (LNG) with high energy density offers a cost-efficient alternative to diesel for waterborne activities (transport, offshore services, and fisheries), trucks and rail, with lower pollutant and CO2 emissions and higher energy efficiency. LNG is particularly suited to long-distance road freight transport for which alternatives to diesel are extremely limited. Trucks might be able to meet the more stringent pollutant emission limits of future EURO VI standards cost efficiently.
LNG is also an attractive fuel option for vessels to meet the new limits for sulfur content in marine fuels decreasing from 1 % to 0.1 % from 1 January 2015 in Sulphur Emission Control Areas (SECAs) in the Baltic Sea, North Sea and English Channel as set by the International Maritime Organisation (IMO). These obligations will be relevant for about half of the 10 000 ships currently engaged in intra-EU shipping. LNG is also an attractive economic alternative for shipping outside SECAs, where sulfur limits will decrease from 3.5 % to 0.5 % from 1 January 2020, and globally.
Lack of fuelling infrastructure and common technical specifications on refuelling equipment and safety regulations for bunkering hamper market uptake. LNG in shipping, on the other hand, could be economically viable, with current EU prices lower than for heavy fuel oil and low sulfur marine gasoil, and prospects of increasing use in future.
LNG development into a global commodity can improve security of energy supply in general by boosting the use of natural gas as fuel for transport. LNG use in transport can also increase the value of gas that would be otherwise flared.
Compressed natural gas (CNG)
Natural gas vehicle technology is mature as regards the broad market, with close to 1 million vehicles on the road in Europe and around 3 000 filling stations. Additional refuelling stations could easily be supplied from the existing dense natural gas distribution network in Europe, provided the quality of gas is sufficient for CNG vehicles.
CNG vehicles have low pollutant emissions and have therefore rapidly gained ground in urban fleets of buses, utility trucks and taxis. Optimised gas-only vehicles can have higher energy efficiency.
An economically viable market development could be expected by private initiatives as CNG vehicles are competitive with conventional vehicles in price and performance, and natural gas is cheaper than petrol and diesel. But public intervention is necessary to avoid fragmented EU level markets and to enable EU-wide mobility for CNG vehicles.
Gas-to-liquid (GTL)
Natural gas can also be transformed to a liquid fuel by first decomposing it to a ‘synthesis gas’, consisting of hydrogen and carbon monoxide, and then by refining to a synthetic fuel with the same technical characteristics as conventional fuels, fully compatible with existing combustion engines and fuel infrastructure. Synthetic fuels can also be produced from waste feedstock. They improve the security of supply and reduce pollutant emissions of present vehicles. Moreover, they promote advanced engine technologies of higher energy efficiency. Excessive cost, however, presently limits market take-up.