Imagine an engine that runs on water.

No more genuflecting to OPEC. With something like 326 million trillion gallons of go-juice laying around in plain sight, we can tell Saudi Arabia to stick it in its bore hole and laugh out loud as the screen door hits Venezuela in the Caracas.

No more air pollution. Water in, water out. Goodbye smog, hello fog. Imagine the universal jubilation as the scourge of global warming caused by excessive carbon dioxide in the atmosphere is transformed overnight into the menace of global cooling caused by a vast eruption of squeaky-clean water vapor that blots out the sun in a perpetual anthropogenic monsoon of benign emissions.

It could happen.

But not today.

Fact is, the theoretical potential for a water-fueled engine has been around since at least 1799, when English chemist William Nicholson discovered that a small electrical charge applied to a beaker of H₂O will split the liquid’s molecules into their individual atomic elements. The process is called electrolysis, and it can be reproduced today by any half-wit bonobo with a mayonnaise jar, a 12-volt battery and a few inches of copper wire.

It was pretty sharp stuff back in the day, though, and by 1807 an enterprising French tinkerer named Francois Isaac de Revis used electrolysis to lay in a store of pure hydrogen and lashed together a motor to burn it in. The result was the world’s very first combustion engine, and it can fairly be said to have run on water. It was a scientific triumph, a commercial failure, and the first lap of a 200-year race to produce a viable successor.

Like electrolysis, the principles behind the water-powered engine are pretty basic. Water is composed of two hydrogen atoms and one atom of oxygen (H₂O). Hydrogen – the most abundant element in the universe comprising about three-quarters of all known matter – is a highly flammable and efficient fuel capable of delivering more than twice as much bang for the buck as gasoline.

Water – fresh, tap, salt or otherwise – is fed into an electrolysis “fuel cell” where its hydrogen and oxygen atoms part company. Freed of their fire-retardant oxygen baggage, the hydrogen atoms are channeled into a combustion chamber. When ignited, they instantly re-combine with oxygen, releasing energy, and the repatriation of the sundered elements creates no residue more harmful than San Pellegrino

In theory, the pure water thus exhausted can be fed back into the fuel cell where, in theory, the energy it just produced can divide it again, creating, in theory, a self-sustaining system. In theory it’s the perfect perpetual-motion machine, and the only reason we’re not all driving around in 12-cylinder water-fueled Cadillacs is because all that giddy theorizing eventually crashes headlong into the immutable bridge-abutment of Natural Law.

Specifically, our hypothetical water-powered car shamelessly violates the First Law of Thermodynamics, which inconveniently insists that the total energy of an isolated system is constant. As Revis discovered to his chagrin, it takes precisely the same amount of energy to split a water molecule apart as it does to mash it back together again. In other words, the energy required by the water engine’s fuel cell is exactly the same amount created in its combustion chamber, and vice versa, leaving exactly no energy left over to perform useful work like, say, making beep-beep go zoom-zoom.

The water engine further falls afoul of the Second Law of Thermodynamics, which decrees that any closed energy system is only as good as the sum of its entropies. Water engines unavoidably shed energy in the form of heat, resulting in a net energy loss that can’t be replaced within the system, as previously harped about in the First Law of Thermodynamics.

But laws, as they say, are meant to be broken, and there’s never been a shortage of gutsy entrepreneurs who believe they can skirt the unreasonable dictates of physics, or who at least believe they can make a pool of trusting investors believe they can. Hardly a year goes by that some intrepid inventor doesn’t pop up on the Internet claiming to have solved the water engine riddle by adding some mysterious electron-rich substance to the water or by some proprietary fuel-cell tweak.

Perhaps the most famous – or infamous – of those maverick mechanics was Stan Meyer, an Ohio resident who 20 years ago claimed to have perfected the technology by adding deuterium to the water supply, and who three years later was successfully sued by a swarm of disappointed speculators. Meyer told everybody who’d listen that a nefarious conspiracy involving jealous automobile and oil interests lay behind his downfall, and when in 1998 he died suddenly in a restaurant parking lot it was assumed among his supporters that he’d been poisoned, a belief undoubtedly fortified by Meyer’s dying utterance, “I was poisoned.”

More recently, if less dramatically, in 2002 a New Jersey outfit calling itself Genesis World Energy convinced a collection of credulous capitalists to back its market-ready fuel cell to the tune of $2.5 million. No GWE fuel cells actually went to market, and in 2006 the company’s owner began serving a five year prison sentence for theft.

In 2008, amid equal parts public fanfare and industrial secrecy, scientists with Japanese-based start-up Genepax announced the perfection of a miraculous Water Energy System, assuring a petroleum-fatigued world that its water energy system was better than all previous water energy systems because they said so. Pressed to prove its claims, the company staged a public demonstration of its water-fueled vehicle, which was immediately recognized by everybody as an Indian-made electric car sold in the United Kingdom as the G-Wiz. Genepax shut down its website in 2009 citing burdensome “development costs.”

But that’s not to say you can’t burn hydrogen in your Outback if you feel like it. There are currently at least a dozen concerns that will gladly sell you an oxyhydrogen (HHO) kit with the promise of significantly improved gas mileage. Retailing for about $200.00, these devices are essentially modified electrolytic cells that split water molecules and blend the resulting gases into a flammable mixture two parts hydrogen and one part oxygen (ergo, HHO), which it pipes into your engine’s intake manifold on the not-unreasonable premise that the more oxyhydrogen you’re burning the less gasoline you’ll need. Alas, even that timid nod to water-power has its detractors, most of them pointing out that since the average family sedan gulps down about 500 liters of air per minute, and the average HHO generator cranks out less than a liter of oxyhydrogen per minute, any relief you experience at the pump will be of the purely psychological kind.

And it’s not to say that some folks aren’t burning water every day, after a fashion. The U.S. Navy, for example, is enjoying considerable success using sea water to fuel its jet aircraft, the difference being that instead of trying to burn its water-derived hydrogen, properly equipped Naval carrier vessels also separate sea water’s abundant store of carbon dioxide and distill the two gases into a hydrocarbon liquid jet fuel, in effect manufacturing their own high-seas brand of ersatz petroleum byproduct.

It’s all very discouraging. Will we ever tap the infinite power of water? Ever break the grip of Big Oil? Ever free the skies of noxious carbon emissions, or rejoice together as the mighty glaciers of yore march south once more bearing an inexhaustible cargo of frozen energy?

Maybe.

Just not today.