Toyota’s “Water Engine”: Understanding the Hype, Reality, and the Numbers
You might have heard the buzz about Toyota’s “water engine” — a revolutionary concept promising to run cars on water instead of gasoline. It sounds incredibly exciting, but what’s the real story?
Not Quite Powered by Water
It’s important to know that no engine runs purely on water. Water itself cannot be burned as fuel. Toyota, leading innovation in the field, is exploring two main approaches:
- Hydrogen Fuel Cell Vehicles (FCEVs): Cars like the Toyota Mirai use hydrogen fuel, which can be generated from water through a process called electrolysis. However, these cars still carry pre-made hydrogen on board.
- Hydrogen Combustion Engines: Toyota’s experiments involve engines that burn hydrogen directly, much like traditional cars burn gasoline. Again, the hydrogen needs to be produced first, often still from water via electrolysis.
What about Onboard Electrolysis?
Toyota is researching the possibility of performing electrolysis inside the car itself. This could potentially mean you refill with water instead of searching for hydrogen fueling stations. However, there are major challenges:
- The Energy Math: We did some rough calculations. One liter of water contains enough hydrogen to hold about 13.2 megajoules of potential energy. However, electrolysis is inefficient, and a typical internal combustion engine only converts about 30–40% of fuel energy into usable power. After considering these losses, you might only be able to drive around 3–4 kilometers on that liter of water!
- Complexity and Cost: Integrating an onboard electrolyzer would make the vehicle more complex and expensive.
The Bottom Line
While onboard electrolysis fueled by water has exciting potential, significant technological breakthroughs are needed before it becomes a practical replacement for gas-powered cars. A 40-liter water tank would likely only get you 120–150 km. Toyota’s work on hydrogen-based technologies still holds promise for a future of ultra-clean transportation, but it’s a journey in progress.