‘Mirai’ may mean ‘Future’ in Japanese, but Toyota’s first mass production fuel cell car has origins as far back as the mid-nineties. That is when the Japanese manufacturer laid out a strategy that was aimed at guaranteeing sustainable mobility for the 21st century.

Toyota’s goal was threefold. First, to improve overall efficiency, allowing drivers to do more with less. Secondly, to diversify the energy sources used to propel cars, in order to reduce dependence on dwindling oil reserves. And finally, to reduce the environmental impact of personal mobility. 

Hybrid is the cradle

To this day, the most legendary heir of that strategy is the petrol-hybrid Prius. By combining a petrol engine with an electric motor, the concept behind Prius was as simple as it was ingenious. On the one hand, the car was able to recapture energy that traditionally goes to waste under braking, and store it in a compact on-board battery. And on the other hand, this battery fed an electric motor that could step in to support the engine, reducing its thirst for fuel. Through a clever gearbox, the system allowed petrol and electric to work in perfect symbiosis, and even permitted the engine to run as often as possible in its most efficient rev-range. Any surplus power was simply turned into electricity and sent to the battery.

Seen by many at first as little more than an oddity, Prius and its powertrain gradually won fans. Technology lovers chose it for its high tech content, environmentalists for the greener form of transport that it promoted. And when the rich and famous embraced it and started selecting it over the luxury barges and supercars that they preferred in the past, awareness and appreciation rocketed.

Today, hybrid technology has found its way into various other models of the Toyota range. One in three Yaris sold in Europe today is hybrid and the same goes for 40% of all Auris. Nor is Toyota longer alone as a hybrid manufacturer: in recent years, other brands have started to follow suit – including some of the brands that had been highly critical of the technology at the beginning.

Battery electric vehicles for last mile mobility

Less well known, is that Toyota’s plans extended much further. Its strategy placed hybrid at the heart of the future car market, but it also foresaw a clear role for electric vehicles. Having invested in battery research in its own Physical and Chemical Research institute founded as far back as 1940, Toyota didn’t hold out much hope for a sudden break-through in batteries that would suddenly make EVs a valid mass-market alternative for the regular family car. However, it did see opportunities for small battery-powered vehicles as an alternative for urban, last-mile mobility. In such usage, driving range is less of a priority, so the battery pack can be kept compact and light, in itself helping efficiency. The latest personification of this concept is the Toyota i-Road, which is deployed in pilot car-sharing programmes in Japan and in the French city of Grenoble.

Fuel Cell for high mileage vehicles

At the other end of the scale, for large vehicles designed for long distance travel, Toyota started researching Fuel Cell technology. Using hydrogen as a source for on-board electricity generation yielded a very different type of electric vehicle: one that was not limited by range or by recharging time.

In the subsequent development of EVs and Fuel Cell cars, Toyota relied heavily on the architecture it had devised for its hybrid powertrains. The principle of energy recuperation was applied to both vehicle types, whereas the hybrid concept was adopted in its entirety for the Fuel Cell prototypes.  Here, the petrol engine from a traditional hybrid was simply replaced by a Fuel Cell stack, and the petrol tank by hydrogen tanks.

Today, after more than fifteen years of development, Mirai’s basic architecture borrows from that of the very first Prius. And several parts of its powertrain, such as the motor and the traction battery, are proven components that are shared with other Toyota hybrids.

Going forward, Toyota Fuel Cell cars can be expected to continue to benefit from the company’s ever strengthening expertise of hybrid technology.

 

Thanks to its hybrid knowledge, Toyota created the first fuel cell production car. It is a vehicle driven by an electric motor powered by the electricity generated by the chemical reaction between on-board hydrogen and airborne oxygen. Compared to the Prius, the new Toyota Fuel Cell Sedan has replaced its combustion engine by a fuel cell stack and its fuel tank by a hydrogen tank. Two high-pressure tanks actually, that store the hydrogen at a pressure up to 700 bar and that can be filled up in about 3 minutes. The only emission is water.

Hydrogen + Oxygen –> Electricity + Water

 

Built on the hybrid architecture, the Toyota Fuel Cell Sedan features a battery, a boost converter, an electric motor and a power control unit for the handling of the 4 different phases of working.

At very low load driving, meaning at very low speeds or in traffic jams, it is the battery only that provides the energy to drive the car.

At low load driving, meaning at low speeds like in city centres, the fuel cell stack provides enough energy for feeding the electric motor and simultaneously charging the battery.

At high load driving, when a lot of power is required, the fuel cell stack and the battery work together in order to boost the acceleration.

And then, as for a hybrid car, energy is recovered during braking and used for recharging the battery.
The fuel cell stack is composed by hundreds of cells. In each cell it works as follows:

1. Hydrogen is supplied to the anode side.
2. Hydrogen molecules activated by the anode catalyst release electrons.
3. The electrons released from hydrogen travel from the anode to the cathode, creating an electrical current.
4. Hydrogen molecules that released electrons become hydrogen ions and move through the membrane
5. Hydrogen ions bond with oxygen and electrons on the cathode catalyst to form water.

By generating its own electricity from hydrogen, the fuel cell car can help make a future hydrogen based society a reality, and contributes to energy diversification.

Have a look at our Fuel cell video on YouTube!