The physics of why a water-fuelled car is a scientific impossibility
In short: From 1930s patents to modern-day billion-dollar claims, the dream of an automobile powered by water has captivated the public. But beneath the headlines of infinite energy lies a fundamental barrier: the laws of thermodynamics. To turn water into fuel, you must first break its most stable bonds.
The central allure of the water-fuelled car is the idea of extracting chemical energy directly from water. However, water is an incredibly stable molecule with a negative enthalpy of formation (−68.3 kcal/mol or −285.8 kJ/mol). This stability means that energy must be actively supplied to break the chemical bonds between hydrogen and oxygen. According to the first law of thermodynamics, any energy harvested from recombining these elements can never exceed the energy used to separate them in the first place.
Most much-publicized claims rely on electrolysis to split water into hydrogen and oxygen. While this process is real, the second law of thermodynamics dictates that the useful energy output will always be less than the input due to inevitable losses. Consequently, these devices cannot produce a net energy gain. Many historical figures, such as Stanley Meyer, who claimed his dune buggy could run on water, were later found to be fraudulent. In 1996, an Ohio court found Meyer guilty of 'gross and egregious fraud.'
It is important to distinguish between true water-fuelled cars and 'hydrogen on demand' systems. The latter are not physically impossible; they use reactive chemicals like aluminium, magnesium, or sodium borohydride to produce hydrogen when they contact water. In these cases, the energy comes from the chemical itself, which eventually depletes and must be replenished. Similarly, 'hydrogen fuel enhancement' uses small amounts of hydrogen to improve the efficiency of conventional gasoline, but the water is not the primary energy source.
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- Summary by Intellect · source: Water-fuelled car
- Also: Journal of neuro-oncology — CAR-T cell therapy: potential for paediatric brain tumours-an update. · CC BY
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