|FCX Concept with the Home Energy System for refueling. Click to enlarge.
Honda’s new FCX fuel cell concept vehicle, unveiled at the Tokyo Motor Show, is a stylish sedan featuring a redesigned fuel cell system that delivers more power and increased range in less space than the current FCX 2005 model on the road, and a low-floor design that maximizes cabin space.
Enabling the low-floor design is Honda’s new “3V” system: vertical gas flow, vertebral layout, and volume-efficient packaging.
|The V-Flow system. Vertical gas flow, vertebral layout, volume-efficient. Note the cutaway of the rear wheel showing the in-wheel motor. Click to enlarge.
In the 3V schema, oxygen and hydrogen flow from the top to the bottom of the fuel cell stack (vertical gas flow) and the fuel cells are arranged vertically in the center tunnel (vertebral layout) for new, high-efficiency fuel cell packaging (volume efficiency).
Compact enough to fit neatly into the center tunnel but robust enough to deliver 100kW of power, the V Flow fuel cell stack offers both space efficiency and high energy output. The key to fuel cell performance is water management. With vertical gas flow, an innovative process in which oxygen and hydrogen flow downward through the stack, Honda’s new fuel cell stack takes full advantage of gravity to efficiently discharge water formed during electricity generation.
By contrast, the FC stack in the FCX 2005 offers a maximum of 86 kW. (Earlier post.)
This improves system performance in sub-zero temperatures, achieving a new level of system reliability. The problem of cold-weather startup had been a key obstacle to the commercialization of fuel cell vehicles. In 2003, Honda solved the problem with the introduction of the Honda FC Stack, the world’s first fuel cell that can be used at temperatures as low as –20° C. The V Flow fuel cell stack, on the other hand, now delivers ultra-low-temperature start-up performance on par with that of a gasoline engine.
|The 25-kW in-wheel motor
The FCX-V Concept drive train features three energy-efficient motors: one in the front and two in the rear. The efficient delivery of this power through all four wheels and the low-center-of-gravity platform combine to deliver torquey performance and agile handling. The space-efficient layout also contributes to the interior efficiency of the low-floor design, eliminating the need to use floor space for motors.
Coaxial motor and gearbox. The 80-kW front-drive motor output shaft is coaxial with the gearbox for a more compact package and a shorter front-end.
Rear in-wheel motors. Each of the rear wheels contains a thin, eccentric 25-kW motor.
To increase the driving range, Honda engineers chose not to increase storage tank pressure, but to use a newly-developed hydrogen absorption material that doubles the capacity of the tank to 5 kg of hydrogen at 350 atmospheres. With the new material, the tanks supply enough hydrogen to extend the cruising range to 560 kilometers (350 miles)—exceeding the DOE’s range target for 2010.
Again, by contrast, the current FCX 2005 model offers a range of 190 miles.
Honda also unveiled its current model of the Home Energy Station (HES), a home cogeneration and fueling system that uses natural gas to supply electricity and heat in addition to hydrogen fuel for vehicles.
The system is equipped with fuel cells that generate electricity (5 kW) for the home, and is configured to recover the heat produced during power generation for domestic water heating. The HES can produce 3 Nm3/hr of hydrogen. In addition to reducing carbon dioxide emissions by some 40%, according to Honda’s calculations, the HES system is expected to lower by 50% the total running cost of household electricity, gas and vehicle fuel.