What Will Replace Fuel? The Emerging Mosaic of Clean Energy Carriers

There won’t be a single replacement for fossil fuel; instead, most end uses will switch to electricity from renewables and nuclear, backed by batteries and other storage, while hard-to-electrify sectors rely on hydrogen and its derivatives, sustainable biofuels, and synthetic e-fuels. In practice, that means electric vehicles for most road transport, heat pumps for buildings, green hydrogen and electrification for heavy industry, sustainable aviation fuel for planes, and methanol or ammonia for shipping. Below is a detailed look at how this transition is unfolding and what to expect next.

The Big Picture: Electricity Becomes the Primary “Fuel”

Globally, the energy system is pivoting from burning molecules to moving electrons. Solar, wind, hydro, nuclear, and geothermal increasingly supply electricity, which then powers end uses directly where feasible. For sectors that cannot easily electrify—long-haul aviation, maritime shipping, high-temperature industrial heat—new low-carbon molecules (green hydrogen, ammonia, e-methanol, and sustainable biofuels) fill the gap. This diversified mix reflects cost trends, technology maturity, infrastructure realities, and policy commitments through the 2030s.

The following list outlines which energy carriers are expected to replace fossil fuels across major sectors and why each is suited to its niche.

• Light-duty road transport: Battery-electric vehicles (BEVs) dominate due to high efficiency, falling battery costs, and expanding fast-charging networks; some plug-in hybrids persist as a bridge.
• Heavy trucks, buses, and off-road: A mix of battery-electric (especially for regional routes), hydrogen fuel cells for longer ranges or fast refueling needs, and overhead/catenary or depot charging where routes are fixed.
• Aviation: Sustainable aviation fuel (SAF) from waste-based biofuels scales first, with synthetic e-fuels (power-to-liquids) growing later; short-haul electric and hydrogen aircraft are niche in the 2030s.
• Shipping: Methanol and ammonia (produced from green hydrogen) begin to replace heavy fuel oil; efficiency measures and wind-assist technologies further reduce fuel demand.
• Buildings: Electric heat pumps replace gas and oil boilers; district heating expands in dense areas; thermal storage smooths peaks.
• Industry: Direct electrification (induction, resistance, electric boilers), green hydrogen for steel and chemicals, and some biomass for process heat; carbon capture remains targeted where process emissions persist.
• Power system: Wind and solar provide most new capacity; batteries, pumped hydro, and long-duration storage handle variability; firm low-carbon resources (nuclear, geothermal, hydro, and gas with CCS in some regions) provide reliability.

Taken together, these shifts point to electricity as the default “fuel,” with clean molecules strategically applied in the toughest segments. The result is a more efficient, modular, and resilient energy system.

Sector-by-Sector: How the Replacement Unfolds

Road Transport

Battery-electric vehicles are set to replace gasoline and diesel for most cars, vans, and many trucks. Global EV sales share continues to rise, supported by more models, improving range, and denser charging networks. In 2024–2025, early sodium-ion batteries appear in city cars and stationary storage, complementing lithium-ion. For heavy-duty trucking, manufacturers are fielding battery trucks for regional haul and piloting hydrogen fuel-cell trucks for longer routes or extreme duty cycles. Depot charging and megawatt charging systems are key enablers.

Aviation

Jet fuel won’t disappear quickly, but its carbon intensity will. Sustainable aviation fuel made from waste oils, fats, and residues is scaling under mandates like the EU’s ReFuelEU (ramping from 2025). E-fuels made from green hydrogen and captured CO2 are entering pilot production this decade, with costs expected to fall as electrolyzers scale and renewable power gets cheaper. Short-hop electric and hydrogen aircraft are under development but will likely remain niche through the 2030s due to weight and infrastructure constraints.

Shipping

Maritime players are beginning to adopt green methanol and, later in the decade, ammonia. Newbuild orders for methanol-capable vessels surged, and the first ammonia-capable engines have been validated, with safety protocols developing in parallel. Ports are building bunkering infrastructure for these fuels. Efficiency upgrades—like hull design, slow steaming, and wind-assist—reduce overall fuel demand, smoothing the transition.

Buildings and Heating

Electric heat pumps replace combustion heating in homes and commercial buildings, typically cutting energy use by two-thirds compared with boilers. Despite a recent sales slowdown in parts of Europe as gas prices eased, long-term policy and building codes continue to push electrification. District heating, waste heat recovery, and geothermal networks expand in urban areas. Thermal storage—water tanks, phase-change materials—helps manage peak loads as winter electrification grows.

Industry

Heavy industries replace fossil fuels through a combination of electrification, hydrogen, and process innovation. Steelmaking is shifting from blast furnaces to direct reduced iron using green hydrogen, with European and Middle Eastern projects slated to start production mid-to-late decade. Chemicals adopt green hydrogen and electrified crackers over time. Where process emissions are intrinsic (cement), carbon capture is likely necessary alongside alternative binders and clinker substitutes.

Power Generation and the Grid

Solar and wind set new installation records in 2023–2025, and nuclear remains a significant low-carbon backbone in some regions—e.g., new Vogtle capacity in the U.S. came online, while advanced reactor projects like TerraPower’s Natrium broke ground. Grid-scale batteries multiply for short-duration balancing, and long-duration storage (iron-air, flow batteries, thermal storage) moves from pilots to early commercial projects. Transmission expansion and smart demand management (EV charging orchestration, flexible heat pumps, industrial demand response) become as critical as generation capacity.

Why This Mix Will Dominate

Several reinforcing trends explain why electricity plus clean molecules is outpacing other approaches.

• Efficiency: Electric drivetrains and heat pumps convert energy to motion and heat far more efficiently than combustion, reducing primary energy demand.
• Cost and learning curves: Solar, wind, batteries, and electrolyzers keep getting cheaper as deployment scales; 2024 saw renewed declines in battery costs and strong growth in renewable capacity.
• Policy and mandates: Clean energy standards, EV targets, SAF blending mandates, and carbon pricing increase market certainty and accelerate infrastructure build-out.
• Supply chain maturation: Rapid expansion of battery materials processing, component manufacturing, and electrolyzer production is easing bottlenecks, with diversification across regions.
• System integration: Advances in software, forecasting, and grid management allow higher renewables penetration without compromising reliability.

These drivers make electrification the default choice where practical, with hydrogen-derived and bio-based fuels used sparingly where they deliver the most value.

What Likely Won’t Replace Fossil Fuels on Its Own

Some options are important but unlikely to become universal, single-source replacements.

• Hydrogen for passenger cars: Fuel-cell cars face higher costs and sparse fueling infrastructure versus rapidly improving BEVs.
• Corn- or crop-based biofuels at large scale: Sustainability and land-use limits constrain their growth; waste-based and advanced biofuels are preferred.
• “Blue” hydrogen everywhere: It can play a role where CO2 storage is viable, but lifecycle emissions depend on methane control and capture performance.
• Nuclear fusion this decade: Significant R&D momentum exists, but grid-scale fusion is not expected to meaningfully displace fuels before the 2030s–2040s, at best.
• Direct air capture as a primary solution: Useful for hard-to-abate residuals and for synthetic fuels, but far too energy- and cost-intensive to replace mitigation.

In short, these technologies may be valuable in specific contexts or in the longer term, but they do not obviate the near-term shift to electrification and targeted use of clean molecules.

Milestones to Watch (2025–2035)

The following timeline highlights developments that indicate the replacement of fossil fuels is on track.

1. 2025–2027: Continued record global solar and wind additions; expansion of transmission and grid-scale batteries.
2. 2025–2028: Rapid growth of medium- and heavy-duty electric trucks on regional routes; early fuel-cell truck corridors established.
3. 2025–2030: SAF blending ramps under EU and other mandates; first commercial e-fuel plants scale beyond pilot.
4. 2026–2030: Green hydrogen projects reach larger scale; first commercial green steel shipments from Europe and the Middle East.
5. 2027–2032: Long-duration storage (iron-air, flow, thermal) moves from demonstration to portfolio role in multiple grids.
6. 2028–2035: Broader rollout of ammonia/methanol bunkering; ammonia-capable engines enter regular service in shipping.
7. Through 2035: Heat pump retrofits accelerate with incentives and building codes; district heating expands in cities.

Tracking these markers helps assess whether clean electricity and low-carbon fuels are replacing fossil fuels at the scale and speed required.

Risks and Constraints

Several challenges could slow or reshape the transition and merit active management.

• Permitting and interconnection: Delays for new transmission, wind, and large solar projects can bottleneck deployment.
• Critical minerals: Sustainable, diversified supply of lithium, nickel, cobalt, copper, and rare earths remains essential; recycling and alternative chemistries help.
• Infrastructure gaps: Charging networks, hydrogen pipelines, CO2 transport/storage, and port bunkering must scale in lockstep with vehicles and fuels.
• Market design: Capacity, flexibility, and ancillary services markets need updates to value storage, demand response, and firm low-carbon resources.
• Social acceptance and workforce: Community engagement, fair siting, and skilled labor availability are vital for build-out.

Addressing these issues proactively reduces costs, mitigates delays, and ensures reliability during the transition away from fossil fuels.

Summary

No single fuel replaces fossil fuels. Electricity from renewables and nuclear becomes the primary energy carrier for vehicles, buildings, and many industrial processes, enabled by batteries and smart grids. Where electrons can’t easily do the job—long-haul aviation, deep-sea shipping, high-temperature industrial heat—clean molecules take over: green hydrogen and its derivatives (ammonia, e-methanol), plus sustainable biofuels and, in some cases, carbon capture. With record renewable additions, falling storage costs, advancing hydrogen projects, and rising mandates for cleaner fuels, the 2025–2035 period will cement this mosaic. The outcome is a more efficient, diversified, and resilient energy system that steadily displaces fossil fuels across every major sector.

What will be the next fuel source?

Hydrogen
Hydrogen can also be used to power a fuel cell and produce electricity. This is the solution many consider to be one of the best longer-term energy sources for cars: it produces zero emissions and overcomes the limitations of onboard batteries.

What is the next fuel source for cars?

The most probable next fuel sources for cars include electricity for battery-electric vehicles (BEVs) and hydrogen for fuel cell electric vehicles (FCEVs), with other alternatives like biofuels, synthetic fuels, and compressed natural gas (CNG) also playing a role, especially in different sectors or for specialized applications. Electricity is currently the most widespread alternative, while hydrogen offers benefits like longer range and faster refueling, though it faces infrastructure challenges.
 
Leading Alternatives

• Electricity (BEVs): Battery-powered vehicles, charged by electricity, are a dominant alternative fuel source for cars today, offering a zero-emission driving experience. 
• Hydrogen (FCEVs): Hydrogen is a strong contender for the future, powering fuel cell electric vehicles that produce electricity to drive the car. Hydrogen cars, also known as FCEVs, have the potential to offer better driving range and quicker refueling compared to BEVs. 
  • Benefits: Hydrogen fuel cells produce only water and heat as byproducts, making them very eco-friendly. 
  • Challenges: A significant lack of hydrogen fueling infrastructure is a major hurdle to their widespread adoption. 

Other Potential Sources

• Biofuels (Biodiesel, Ethanol): Opens in new tabThese fuels are derived from plant-based sources, such as vegetable oils or algae. They are seen as a more sustainable option and can be used in existing engines. 
• Synthetic Fuels (E-fuels): Opens in new tabThese are fuels created using renewable electricity, water, and captured carbon dioxide. They can potentially fuel existing gasoline and diesel vehicles, extending their life cycle. 
• Compressed Natural Gas (CNG) / Bio-CNG: Opens in new tabNatural gas, which can be a carbon-friendly option when sourced renewably (as bio-CNG), is an available fuel with cost advantages over gasoline and diesel. 

Factors for Success
The “next” fuel source for cars depends on several factors, including cost, existing infrastructure, technological advancements, and environmental impact. While electricity is the current leader, hydrogen and other emerging fuels are likely to share the future, with the best option often determined by the specific application and needs of the driver or region.

What is a good substitute for gasoline?

Gasoline alternatives include biofuels like biodiesel and ethanol, gaseous fuels such as hydrogen, natural gas, and propane, and electricity. These fuels power specialized vehicles like flex-fuel cars, fuel cell electric vehicles, natural gas trucks, and battery-electric vehicles. Other options are renewable diesel and synthetic fuels, which are either derived from organic matter or created using hydrogen and captured carbon, respectively, to be carbon-neutral.
 
Biofuels

• Biodiesel: Made from vegetable oils and animal fats, it can be used in diesel engines with little to no modification. 
• Ethanol: Produced from plants, it can be used as a blend with gasoline in flex-fuel vehicles. 
• Renewable Diesel: A biomass-derived fuel suitable for diesel engines. 

Gaseous Fuels

• Hydrogen: Powers fuel cell vehicles, which are highly efficient and emit only water. 
• Natural Gas: Available as compressed natural gas (CNG) and can be produced from organic waste as renewable natural gas. 
• Propane: Also known as liquefied petroleum gas (LPG), it is a clean-burning fossil fuel and can also be produced from renewable sources. 

Electricity 

• Electric Vehicles: Powered by electricity stored in batteries, offering a zero-tailpipe-emission solution.

Other Alternatives

• Synthetic Fuels: Opens in new tabThese fuels are made by combining carbon captured from the air with hydrogen (itself sourced from water). While the combustion of these fuels releases CO2, it is theoretically carbon-neutral because the CO2 was captured from the atmosphere. 
• Advanced Diesel: Opens in new tabWhile not a complete alternative to gasoline, this option can achieve emission levels comparable to low-emission gasoline engines and offers better fuel economy, according to the Environmental & Energy Study Institute. 

What will replace gasoline in the future?

• Biodiesel | Diesel Vehicles.
• Electricity | Electric Vehicles.
• Ethanol | Flex Fuel Vehicles.
• Hydrogen | Fuel Cell Vehicles.
• Natural Gas | Natural Gas Vehicles.
• Propane | Propane Vehicles.
• Renewable Diesel.
• Sustainable Aviation Fuel.