Water- and Air-Powered Cars: Do These Vehicles Really Work?

Water-powered cars are not a new idea. Water heated into steam propelled horseless carriages long before the development of the internal combustion engine. But with steam, you need another fuel source to heat the water, so the water isn’t actually the vehicle’s fuel, but instead a means of transferring energy to turn the wheels. The goal of a water-powered vehicle is to propel the vehicle using the hydrogen and oxygen contained in the water.

Hydrogen is a powerful and clean fuel, and the element is abundant in nature. However, hydrogen molecules in their natural state are bonded to other elements, such as oxygen or carbon. To use hydrogen as a fuel, you have to break the bond with the paired element. Applying electrical current in a relatively simple process called electrolysis is the easiest way to split hydrogen from water. Unfortunately, the energy trade-off between the electricity required to free the hydrogen and the power the hydrogen can produce isn’t a favorable one. Clearly a better process than electrolysis would be required for this. There are claims that the process does exist, but so far this is the stuff of urban legends and conspiracy theories.

The most famous involves Ohio-based inventor Stan Meyer, who demonstrated a dune buggy that ran on water. His onboard “water fuel cell” (not a traditional hydrogen fuel cell) extracted hydrogen from water through a process that “fractured” water. Unfortunately, Meyer died suspiciously in 1998, leading to speculation about his death and his invention. Other inventors and companies have followed the water car dream, while some scientists have debunked the concept as a myth, stating that basic laws of physics and thermodynamics would have to be broken for the device to work. One fact that can’t be ignored is that there are still no commercially viable water-powered cars on the road.

The same, however, is not entirely true of air-powered cars. Cars powered by compressed air do exist, and there are plans to market them around the world. Like water, air power is actually an old idea finding new life through fresh engineering. Former race car engineer Guy Negre of Motor Development International (MDI) has produced a piston engine driven by compressed air that produces enough power for small, lightweight city cars. MDI claims the air car prototypes have a range of 125 miles on flat roads and a top speed of 70 mph. Air is stored in carbon-fiber cylinders below the vehicle, and the tanks can be refilled in a few hours at home or in a few minutes using an electric-powered, high-pressure pump that could be installed at a gas station.

MDI made news in 2007 when India’s Tata Motors licensed the technology as an answer to India’s growing air pollution problem. The compressed-air engine seemed a good match for Tata’s lightweight, $2,500 Nano city car that was designed to be a scooter replacement. A few years ago, Tata said it was hoping to start producing air-powered cars by 2010. Now it’s 2010, and the car doesn’t exist. Plans to distribute an air-powered car in Europe and the United States are also on hold.

Naturally, there are skeptics who say that the air engine is far less efficient than claimed. Until such cars are actually available, no one will be able to attest to their viability. So, are air- and water-powered cars for real? In concept, the answer is yes (for air) and maybe (for water). In reality, neither type of car is readily available.

 — Todd Kaho, executive editor, Green Car Journal

Above:Compressed air technology cars at the MDI factory in France. Photo by Associated Press/Meigneux/Sipa