New things at Honda
High on Hydrogen
Behind the wheel of Honda’s latest fuel-cell concept car.
By BARRY WINFIELD
If anyone can get fuel-cell technology developed at an affordable price level, Honda looks to be in the running.
The company is on its third version of a fuel-cell powertrain, and each one has bumped the performance and range upward, with decreased size and improved efficiency. In the latest form, Honda’s FCX features a new V Flow fuel-cell stack with a claimed power-to-volume density increase of 50 percent, and a power-to-weight density improvement of 67 percent. The stack is 20-percent smaller and 30-percent lighter than the current version. The total powertrain mass has been reduced by almost 400 pounds, and the output has jumped from 86 to 100 kilowatts.
The system is also now more tidily packaged, with the fuel-cell stack residing neatly in the car’s central tunnel. That packaging improvement is possible because the stack orientation has changed; now the hydrogen and water flow through the system vertically instead of horizontally. That facilitates faster water evacuation, which is a key to efficient stack operation. The system now operates at a much lower temperature, capable of starting up in ambient temperatures as low as minus 20-degrees F. Coupled to a new lithium-ion storage battery and a 127-horsepower AC synchronous motor, the energy source
provides a range of up to 350 miles, according to Honda.
At Honda’s Tochigi proving ground, where we drove the new FCX, the only evidence of all this advancement is a futuristic but spacious vehicle that moves off briskly with a whisper of sound, accelerates fairly quickly to highway cruising speeds, and continues on to a top speed of 100 mph. Steering and ride quality seemed to be typical of Honda products, with no sense of large weight or unwieldiness in the admittedly limited confines of a high-speed oval. With all the fuss made about fuel-cell technology, it’s easy to forget that vehicles using this energy source are just electric vehicles at heart, with no exciting exhaust note or interesting transmissions to light the enthusiast’s flame. Still, having 189 pound-feet of torque available from rest isn’t a bad thing, and nor is a quiet powertrain or the all-important zero-emissions operation. Honda is planning to market
a vehicle based on this FCX concept in limited numbers in 2008 in Japan and the U.S. Pricing and/or lease arrangements have yet to be decided.
Honda to launch clean diesel in the U.S. within three years.
Next-generation diesel meets the strictest emissions requirements.
BY BARRY WINFIELD, September 2006
The brilliant thing about Honda’s new clean diesel technology is that it does nothing to alter the character of the company’s existing 2.2-liter i-CTDi engine as found in the European Accord, which is much like our
Acura TSX. It is still a torquey little devil, with a baritone growl and pretty strong acceleration after a slightly soft step-off. In Honda’s new clean-diesel application, the engine’s combustion chamber configuration
was optimized for a cleaner burn, the injection time was reduced by a new 29,000-psi common-rail system, and the exhaust gas recirculation (EGR) system efficiency was improved.
But the real big deal in this engine is a new dual-layer NOx catalyst (which supplements the existing carbon-monoxide and hydrocarbon-oxidizing catalyst and particulate trap systems) to help meet stringent
EPA Tier 2 Bin 5 emissions regulations. This appears to address the diesel engine’s conspicuous failure to match the gasoline engine’s low NOx production. Gasoline engines run at a carefully controlled stoichiometric
air-fuel ratio and the exhaust gases are treated by a three-way catalyzation process which reduces NOx by about 99 percent.
This is impossible in the oxygen-rich environment of a lean-burn diesel engine, where three-way catalysts achieve perhaps a 10-percent reduction in NOx. In response, some manufacturers have been employing urea-
injection systems to reduce NOx emissions. But not Honda.
Instead, the company’s new dual-layer catalyst operates in three stages: During lean-burn operation, the lower layer adsorbs NOx from the exhaust stream. Then, when necessary, the engine management system
switches to a richer air-fuel ratio, allowing hydrogen (H2) obtained from the exhaust stream to react with the adsorbed NOx to produce ammonia (NH3). An adsorbent upper layer then temporarily absorbs the ammonia.
As the engine resumes lean-burn operation, the absorbed ammonia in the upper layer reacts with NOx in the exhaust stream, reducing it to nitrogen.
The effect is similar to having an onboard ammonia source (such as Mercedes-Benz’s AdBlue urea supply), but without having to replenish the tank. Honda showed a real-time exhaust-gas trace from conventional
and dual-layer-catalyst–equipped cars running the same cycle, and the new engine’s emissions adhered closely to the EPA-mandated level. Only when accelerated hard did the new system spike above that level, but to a
much smaller degree than did the conventional diesel.
Honda is naturally circumspect in regard to the exact material specification of the new catalyst, but it’s clear that engine management plays a large role in the control of the new catalyst’s functions. So even when
competing car manufacturers reverse-engineer Honda’s components, as they undoubtedly will, they will probably still face significant engineering challenges.