Honda FCX Clarity

Debut: 2008
Maker: Honda
Predecessor: no

Hydrogen fuel cell could be the ultimate solution to our air pollution...

Being a Sc-Fi addict in my teenage, I always dreamt of hydrogen cars. Think about it: by burning hydrogen, you get the power you need, and the only by-product is pure water. No nitrous gas, hydrocarbons or even carbon dioxide. It could be the ultimate solution to our air pollution problem.

In reality, however, it is not as simple. In the 2 past decades, various car makers have been working hard on hydrogen technology. One camp, led by BMW and Mazda, tried to realize hydrogen cars by adapting conventional internal combustion engines to drink hydrogen fuel. This resulted in the experimental BMW Hydrogen 7 and Mazda RX-8 Hydrogen RE. They were more realistic for mass production, but they were also hampered by poor efficiency - hydrogen fuel has much lower energy density than gasoline or diesel, so the same engine capacity produces much lower power and torque than conventional engines do. Moreover, the high-temperature combustion process generates nitrous gases (NOx) besides water vapour, so internal combustion hydrogen engines are not completely clean.

Another camp led by Mercedes and Honda concentrates on developing hydrogen fuel cell. Fuel cell uses a thin layer of Proton Exchange Membrane (PEM) to generate electricity from the chemical reaction of hydrogen and oxygen. Each hydrogen molecule is catalytically dissociated into proton (positive hydrogen ion) and free electron. The latter is absorbed by the anode electrode as useable electric current. The photon migrates though the membrane layer to the other side and reacts with the oxygen in airflow, resulting in pure water and heat. Each fuel cell is therefore a chemical battery with a voltage approximately 0.7V. By stacking hundreds of cells together, you get a large generator to power your electric car. Fuel cell has an efficiency of over 50%, double of internal combustion engines.

FCX looks as futuristic as its technology...

Since the late 1990s, Mercedes-Benz has been experimenting fuel-cell cars in the name “NECAR” and “F-Cell”. However, it was Honda that came first to market fuel-cell cars to the public. In late 2007, Honda announced to produce 200 units of FCX Clarity. They would be leased to interested customers in Japan and USA for 3 years. While its production cost is still way too high for commercialization - some estimate up to US$1 million each - FCX Clarity can prove the technical feasibility of fuel cell technology in real world.

At first glance, the FCX looks as futuristic as its technology, thanks to a wedge and cab-forward shape. It’s almost the same size as an American Honda Accord, just with a shorter front overhang. A set of 16-inch wheels look small these days, but perfectly reasonable for a car having a 100 mph top speed. I am glad that its designers did not pursue form over functions.

Inside, it is even more futuristic. The dashboard design is multilayer and multi-tone, very inviting. A digital speedometer locates above the main instrument pod and as close as possible to the windscreen, so it doesn’t need HUD to keep your vision on the road. The main instrument pod contains a color LCD dial with a fancy name, Powerball. It indicates the status of fuel cell and battery output. Drive economically and the Powerball will glow to green or blue. More unforgiving and it will glow to yellow or red, reminding your environmental guilt.

Although the FCX is an experimental car, its cabin is very well built and trimmed. Bio-fabrics are used extensively throughout the cabin to show its environmental conscious. All passengers enjoy abundance of space as in the American Accord, but here the rear seat is strictly for two because a tall central tunnel extends from the console halfway into the rear passenger compartment. In fact, the central tunnel contains the fuel cell.

The main instrument pod contains a color LCD dial with a fancy name, Powerball.

Honda’s new generation fuel cell is much lighter and smaller than the first generation shown in 2005. It weighs only 67 kg and takes about the space of a desktop computer. However, its associated cooling facility is not small enough to be fitted between the front seats, so the FCX has to sacrifice its middle rear seat. The vertically mounted fuel cell takes advantage of gravity to help fuel drainage, reducing its size and weight. Electric heating helps it to start running at as low as -30 degC. Compared with its 2005 predecessor, it is a big advancement.

The fuel cell can generate up to 100kW (136hp). This output is then converted to AC in the power control unit and powers the front-axle-mounted electric motor. As 189 lb-ft of torque is available right from 0 rpm, the FCX feels quite brisk at take off. As its transmission has only one forward gear and one reverse gear, the acceleration is as linear as you can imagine. Its 0-60 mph time is about 9 seconds, comparable to a conventional 2-liter family car. Top speed is less impressive though, as the transmission is geared to 100 mph only.

As in any hybrid or electric cars, the FCX utilizes regenerative braking to recharge its battery. This Lithium-ion battery is stored under the rear seat so that it takes no extra space – unlike the bulky hydrogen fuel tank that compromises the trunk. When the car comes to a stop, the fuel cell is turned off immediately. Then all the electric power consumption – air conditioning, lighting, control systems, cabin equipments etc. – will be fed by the battery. When the car starts accelerating, the battery provides the initial push until the fuel cell gets back into operation. The hydrogen fuel tank stores liquefied hydrogen at 5000 psi (345 bar). Honda claims 3.92 kg of hydrogen gives it a driving range of 240 miles. Fuel consumption is measured by miles per kg. Converting to EPA figures, you get 79 mpg in city and 68 mpg on highway. Carbon-dioxide emission is… well, zero.

The FCX employs Accord’s suspensions, i.e. double wishbones up front and multi-link at the rear. On the road, apart from a numb electric power steering and slightly abrupt braking – both are common problems to electric and hybrid cars, by the way – its handling and ride is similar to Accord. Despite of its 1630 kg weight, it is quite agile in corners, thanks to the key components that locate low and near the center of its chassis.

You can see hydrogen fuel cell cars as electric cars plus a series of unnecessary electrochemical conversion...

See the car in isolation, FCX Clarity is unquestionably very impressive. It drives nearly as good as conventional cars in terms of performance and handling. Its accommodation and driving range might be a little down on existing standards, but still practical enough for most people. No wonder Honda believes its fuel cell cars could enter mass production in 10 years' time. However, in my opinion 3 hurdles must be overcome first:

1. Price: until now fuel cells are still far more expensive than electric or hybrid technology, let alone conventional engines.

2. Infrastructures for refueling: hydrogen production plants, transportation system and refueling stations cost billions of dollars to build even in a small country. Government policy support will be essential. Without these infrastructures, hydrogen fuel cell cars will never be popular. The FCX is
currently leased to only customers resident near experimental refueling stations built by Shell.

3. It is questionable whether hydrogen fuel cell technology is really clean. The generation of hydrogen from water consumes a lot of electricity, which is largely generated by fossil fuel until now. Of course, we can build solar, wind or hydro power plants to generate hydrogen, but it could be even more efficient using these plants to supply household electricity needs instead of cars. Moreover, if hydrogen cars are to go mass production, it will be doubtful whether we can build as many renewable energy power plants to satisfy the demand. Besides, there are question marks over the transportation and storage efficiency of hydrogen fuel, as liquefied hydrogen gradually vapors and is released back to atmosphere over time.

However, the biggest blow to FCX Clarity & Sons could come from electric cars. From the development of this couple of years, we can see electric cars have received the biggest push from car makers and component suppliers. Their price and performance have been fast improving. You can see hydrogen fuel cell cars as electric cars plus a series of unnecessary electrochemical conversion. Instead of using the electricity from power plants to drive your car directly, they convert the electricity to hydrogen, transport to refueling stations, fill in the car, then convert back to electricity through the PEM reaction to power the car. Each step downgrades the power efficiency. It is no brainer which one is more efficient. In terms of cost, I think battery is also more hopeful than fuel cell to get to reasonable level for mass application.

Because of the aforementioned reasons, I don't think hydrogen fuel cell cars will ever succeed. However, it is undeniable that Honda has done a great job to realize the FCX Clarity as an experimental car, and by the way fulfilled my teenage dream.
The above report was last updated on 18 Jun 2009. All Rights Reserved.


General remarks

FCX Clarity

Front-engined, FWD



Length / width / height 4845 / 1845 / 1470 mm

Wheelbase 2800 mm

Hydrogen fuel cell, AC motor, Lithium battery.


Valve gears


Other engine features

Max power
136 hp

Max torque
189 lbft


Suspension layout
F: double-wishbone
R: multi-link

Suspension features

Tyres front/rear

Kerb weight
1630 kg

Top speed
100 mph (c)

0-60 mph (sec)
9.2* / 8.6**

0-100 mph (sec)

Performance tested by: *C&D, **R&T

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