Why Hydrogen Won't Replace Gasoline in Your Car

Why hydrogen won't replace gasoline in your car

Can hydrogen power cars, trucks, and ships? The short answer is technically yes, but the practical answer is no, at least not for the average driver. Hydrogen is the lightest element, which seems like an advantage but becomes a major issue: it leaks through almost any material. Keeping it compressed at 700 bars—the pressure needed for minimum energy density—requires extremely expensive and heavy tanks, plus a refueling infrastructure that would need to be built from scratch. This is not an opinion; it is thermodynamics.

Water as a carrier: an idea that sounds good but isn't

The recurring question is whether water can be used as a hydrogen carrier to the destination and extracted there for combustion. The technical answer is yes, but not with water as is. There are Organic Liquid Hydrogen Carriers (LOHC), compounds that absorb and release hydrogen through chemical reactions. The problem is that releasing this hydrogen at the destination requires adding energy in the form of heat. Each transformation costs energy, and we have already gone through several: electricity to produce hydrogen, energy to bind it to the carrier, and energy to release it. In the end, only a memory of the initial joule remains.

Some summarize it with a phrase that should be in textbooks: water is hydrogen already burned. If you carry water, you are not carrying fuel: you are carrying ash. To extract energy from it, you would have to spend more than you get.

And e-fuels? The least bad option no one wants to pay for

If hydrogen is not suitable as a direct fuel, why not produce e-fuel, that is, synthetic gasoline based on hydrogen and CO2 captured from the air? Chemically, it is viable. CO2 is not exactly scarce. The problem is the same as always: each step adds cost and reduces efficiency. Producing green hydrogen is already expensive; capturing atmospheric CO2 is also costly; and synthesizing the final fuel is even more so. The result is a liter of synthetic gasoline that can cost several times what fossil fuel costs. When someone says oil is ending, the answer is not that e-fuel is cheap: it is what will remain when there is no alternative.

White hydrogen and the dream of a deposit underfoot

Recently, the idea has circulated that there are natural deposits of hydrogen—called white or geological hydrogen—relatively accessible underground. If confirmed, hydrogen would cease to be an energy vector manufactured with electricity and become an extractive resource with very different costs. In Spain, moreover, the law does not prohibit searching for it, unlike what happens with oil and gas. It is a door that some see slightly ajar. Others recall that, even if it exists, it will remain an extremely explosive gas and that its domestic handling is not trivial.

The problem of the invisible flame

Here it is important to stop at something that rarely appears in green brochures: safety. Anyone who has worked with hydrogen in a laboratory knows it. The hydrogen flame is invisible and exceeds 2,000 °C. This is not a metaphor: it is a temperature at which a limb ceases to exist before you realize it is burning. Anyone who has handled a hydrogen bomb in an organic chemistry lab knows the precautions. This is incompatible with an average driver refueling at a gas station while looking at their phone.

The historical precedent does not help. The Hindenburg airship did not use hydrogen as fuel, but its load of flammable gas was enough to turn the scene into the definitive image of risk. Every time someone proposes hydrogen for mass transport, someone responds with that photograph.

The nuclear alternative and the renewable alternative

The conversation almost inevitably leads to what to do next. Some defend nuclear energy as a fundamental solution: Spain has uranium, and a decisive bet on reactors—including fast neutrons and breeders—would allow utilizing uranium-238, the so-called poor uranium, or maximizing plutonium generation. The problem is not the fuel, but the cost: a plant takes years to build and its initial investment is enormous. In the same time and for the same money, much more renewable energy and storage can be deployed.

Small Modular Reactors (SMRs) appear as a promise, but they have not yet taken off. Reducing size does not reduce safety or management costs, and the smaller the reactor, the more enriched the fuel must be to maintain the chain reaction. Some designs are directly disposable: they are started up, and when the fuel runs out, the entire core is discarded. The waste logistics do not improve.

Storage: the bottleneck no one talks about

If the bet is on renewables, the problem is storing it. Batteries work, but only for daily cycles. Their cost per unit of power is high, and if you intend to move energy from summer to winter, you only give them one cycle a year: dividing that cost between forty cycles instead of seven thousand turns the operation into an economic absurdity. For daily cycles, however, the calculation works out. Solar thermal power—concentrating the sun to heat salts and drive a turbine—has its niche, especially where there is high irradiation and residual heat can be reused for industry. But with photovoltaic panels so cheap, its advantage has narrowed.

The underlying problem: no one has seen a water engine that works

Every so often, the legend resurfaces of an engine that runs on water, a revolutionary invention that oil companies hide. Physics is stubborn: if a guy in his garage extracted more energy than he put in, he would have discovered perpetual motion. All water engines examined have turned out to be frauds. Neutrinos, those particles that pass through the Earth without colliding with anything, do not move a car. And hydrogen, which can move it, requires a chain of transformations that consumes most of the energy along the way.

The uncomfortable conclusion is that hydrogen is not a source of energy: it is a vector, a way to transport energy you have produced elsewhere. And as a vector, it is expensive, difficult to store, and dangerous to handle. For a delivery truck or a ship, perhaps. For the everyday car, no.