Gasoline has dominated personal transportation for more than a century, but a surprising range of other substances can move a car just as effectively when the engineering is right. From kitchen leftovers to compressed air and hydrogen split from water, these unconventional fuels show how flexible the basic idea of powering a vehicle can be. I will walk through five unexpected options that can, in the right setup, move a car without a drop of gasoline while hinting at how future drivetrains might evolve.
Vegetable Oil as Fuel
Vegetable oil as fuel sounds like a backyard experiment, yet it is a serious alternative for diesel-style engines when handled correctly. Straight vegetable oil, often abbreviated SVO, can be burned in compression-ignition engines once the fuel system is adapted to handle its higher viscosity and different combustion characteristics. The concept builds on the same chemistry that underpins Biodiesel, which is defined as a renewable fuel manufactured from vegetable oils, animal fats, or recycled cooking grease for use in diesel vehicles. While biodiesel is chemically processed to behave more like petroleum diesel, SVO systems heat and filter the oil so it can be injected and atomized properly, typically using a two-tank setup that starts the engine on regular diesel or biodiesel before switching to hot vegetable oil once everything is up to temperature.
In practice, drivers who convert older diesel cars or light trucks to run on waste cooking oil often collect used fryer oil from restaurants, filter out food particles, and dewater it before filling a dedicated SVO tank. The appeal is obvious: the fuel is derived from plants that recently absorbed carbon dioxide, so the tailpipe emissions are partially offset by that prior uptake, and the feedstock is frequently a low-cost waste stream. The surprising-car-fuel-sources reporting highlights how unconventional liquids like used cooking oil can, with the right preparation, power a vehicle that was originally designed for fossil diesel. For fleet operators or small businesses, this can reduce fuel bills and local pollution, although regulators still expect road taxes to be paid and modern emissions systems can be sensitive to off-spec fuels. The broader implication is that the diesel engine’s basic design is remarkably tolerant of bio-based oils, which keeps it relevant in a world that is trying to cut net carbon without scrapping every existing vehicle at once.
Wood Gas from Pyrolysis
Wood gas from pyrolysis turns solid biomass into a combustible gas mixture that can feed an internal combustion engine, effectively letting a car run on chunks of wood instead of liquid fuel. In a gasifier, wood is heated in a low-oxygen environment so it does not burn outright but instead breaks down into a mix of carbon monoxide, hydrogen, methane, and other gases often called syngas. During fuel shortages in the twentieth century, thousands of vehicles were fitted with bulky gasifier trailers, and the same principle still works today with more compact hardware. The surprising-car-fuel-sources coverage points to wood-derived gas as one of the more unexpected ways to keep a piston engine running when gasoline is unavailable, because the engine itself can remain largely unchanged while the fuel system and intake plumbing are reworked to accept the low-pressure gas stream.
Modern wood-gas systems typically mount a sealed reactor vessel, cyclone filters, and cooling pipes on a vehicle frame, then feed the cleaned gas into the intake manifold where air and fuel would normally mix. The driver must manage fuel loading and airflow to keep the gasifier in its optimal temperature range, which makes the experience more hands-on than simply turning a key at a pump. From a climate perspective, using sustainably harvested wood or agricultural residues can be close to carbon neutral, since the carbon released was recently stored in plant matter rather than in ancient fossil deposits. However, tar formation, particulate emissions, and the sheer bulk of the equipment limit mainstream appeal. For rural communities with abundant biomass and limited access to refined fuels, the technology demonstrates that even low-value wood can be upgraded into a transport fuel, underscoring how flexible combustion engines can be when paired with creative fuel preparation.
Algae-Derived Biodiesel
Algae-derived biodiesel takes the idea of plant-based fuel into the water, using microscopic organisms that can produce large quantities of oil-rich biomass. Reporting on how Algae could fuel a cleaner road to the future notes that these organisms can be cultivated in ponds or bioreactors and then processed into oils suitable for conversion into biodiesel. Among the American companies making biodiesel is Among the American firm Propel Fuels, based in Redwood City, which has focused on distributing renewable fuels at retail stations. While not all of its product necessarily comes from algae, the example shows how bio-based diesel can be blended into the existing fuel supply and used in standard diesel engines with little or no modification. Because algae can grow on non-arable land and in brackish or wastewater, they avoid some of the food-versus-fuel tensions that surround crops like soy or palm.
Once harvested, algal biomass is typically dried and subjected to mechanical pressing or solvent extraction to pull out the lipids, which are then reacted with an alcohol in a transesterification process to create biodiesel that meets established fuel standards. That finished fuel can be used in passenger cars, heavy trucks, and buses designed for diesel, often in blends that range from a small percentage up to pure biodiesel depending on manufacturer guidance. The Biodiesel definition underscores that this category includes fuels from vegetable oils and recycled grease, and algae-derived oils fit neatly into that framework. For policymakers and investors, the stakes are significant: if algae systems can be scaled economically, they offer a path to high-yield, low-land-use fuel production that plugs into existing infrastructure. For drivers, the experience is intentionally unremarkable, since the goal is to deliver a drop-in fuel that feels like conventional diesel at the nozzle while quietly shifting the carbon accounting behind the scenes.
Compressed Air Propulsion
Compressed air propulsion replaces chemical energy with stored mechanical energy, using high-pressure tanks to drive pistons or air motors that turn the wheels. Instead of burning fuel, the system releases compressed air through an expansion device that converts pressure into motion, similar to how a steam engine uses hot vapor but without combustion in the vehicle. The surprising-car-fuel-sources reporting highlights compressed air as one of the more counterintuitive ways to move a car, because the “fuel” is simply air that has been squeezed by an external compressor, often powered by electricity. In some concept vehicles, the air tanks are integrated into the chassis, and the drivetrain uses a hybrid layout where compressed air assists a small internal combustion engine, improving efficiency in stop-and-go traffic by recovering braking energy as compressed air rather than as electricity.
From an energy perspective, compressed air is not a primary source but a storage medium, so the environmental impact depends on how the electricity for compression is generated. If the grid is rich in renewables, filling a car’s air tanks can be relatively low carbon, and refueling can be quick because high-flow compressors can transfer energy faster than many current battery chargers. However, the physics of compression and expansion introduce losses, and the tanks must be strong enough to handle high pressures while remaining light enough for a vehicle, which raises engineering and safety challenges. For city fleets that operate on fixed routes and return to a depot, compressed air systems could offer a niche solution with simple, robust hardware and no tailpipe emissions. The broader implication is that once a drivetrain is designed to accept mechanical energy from multiple sources, the line between “fuel” and “storage” starts to blur, opening space for unconventional options like air to compete with batteries and liquid fuels in specific use cases.
Hydrogen from Electrolysis
Hydrogen from electrolysis turns water into a transport fuel by splitting H₂O into hydrogen and oxygen using electricity, then feeding the hydrogen into either a fuel cell or a modified combustion engine. In a fuel-cell electric vehicle, hydrogen reacts with oxygen in a stack to produce electricity, heat, and water vapor, which then powers electric motors at the wheels. The idea of using synthetic or alternative fuels to keep combustion technology alive is a recurring theme in discussions about whether new energy carriers can, as one video featuring Will asks, save gas cars or petrol cars by decarbonizing what flows into the tank. Hydrogen produced via electrolysis fits into that debate because, when generated with low-carbon electricity, it can deliver very low lifecycle emissions while still supporting familiar vehicle formats and refueling habits.
Hydrogen can also be burned directly in internal combustion engines with relatively modest changes to fuel delivery and ignition, offering another route to keep existing manufacturing expertise relevant. At the same time, companies are exploring synthetic liquid fuels made from captured carbon dioxide and hydrogen, with one ambitious startup claiming its machine can make gasoline out of thin air so drivers can, as the report puts it, Imagine filling up without guilt. In that scenario, electrolysis supplies the hydrogen that is combined with CO₂ to form hydrocarbons compatible with today’s engines and distribution networks. For governments and industry, the stakes are high: large-scale electrolysis could anchor new green hydrogen economies, reshape energy trade, and offer a lifeline to sectors that are hard to electrify directly. For drivers, hydrogen’s promise lies in fast refueling and long range, but realizing that promise will require extensive infrastructure, careful safety standards, and clear policies to ensure the electricity used to split water is genuinely low carbon rather than just shifting emissions upstream.
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