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Apart from suggesting romantic interludes in classic films (and how's that for dating myself?), the pounding surf is finding other uses. Well, not exactly pounding surf, but rather it's the wave action occurring a bit farther out in the water that's being harnessed in a particularly clever way.

The Pelamis Wave Energy Converter is a semi-submerged array of cylindrical sections linked by hinged joints. Think a string of sausages aligned perpendicularly to the shore. As successive waves articulate the hinges, they also drive hydraulic rams which, in turn, power generators producing electricity.

An array of these devices is tunable to induce a cross-coupled resonant response exploiting local wave conditions. Ideally, the arrays are moored in water 150-200-ft. deep, perhaps 3-6 miles off shore.

And, in fact, I learned all this during my research for October 2006's "Technology Update: Fueling our Mobility." Specifically, I stumbled on Norsk Hydro, a Norwegian company with two core businesses, energy and aluminum. (You may recall the latter is electrical-energy-intensive in its production, so the corporate combination makes a lot of sense.)

On the energy side of its business, Norsk is also involved in a Portuguese wave-farm project producing 2.25 megawatts of completely renewable energy. I did a bit more hunting to learn that 1 MW of electricity is enough to support about 240 homes, so perhaps some 540 Portuguese families near this array are enjoying the cleanest of power (amid images, no doubt, of pounding surf).

An Elegant Production Of Ammonia

In mathematics, something that's simple yet profound is termed "elegant." And, with this in mind, I say Honda's approach to clean diesel power is elegant indeed.

Recall that a diesel is perhaps 20-25 percent more fuel efficient than its gasoline counterpart. But diesels also produce particulates and more NOX. Worse yet, what's good for NOX reduction is bad for particulates, and vice versa.

Other automakers, Mercedes-Benz among them, have proposed urea injection, this ammonia-like compound reducing the downstream NOX. This, however, calls for an onboard canister of urea that needs replenishment, perhaps at oil-change intervals. EPA dislikes the idea, as it prefers emissions controls that are 10-year/150,000-mile foolproof.

Honda's elegant proposal is to finesse the car's emissions-control system into producing its own ammonia. Its catalytic converter has two layers, one adsorbing - i.e., absorbing on its surface - NOX from the exhaust gas and periodically converting part of it into ammonia. The other layer adsorbs the remaining NOX, where it and the ammonia react beneficially.

The operation is dual-mode, depending on engine management's choice of fuel/air ratio.

Much of the time, the engine runs in lean-burn mode, with NOX adsorbed onto the catalyst's lower layer. Periodically, engine management invokes a brief rich-burn mode, sending hydrogen-rich compounds into the exhaust stream and promoting production of ammonia, NH3, in the catalyst's upper layer. With a return to lean-burn - and its oxygen-rich atmosphere - this ammonia and the NOX react to form N2, harmless nitrogen.

Honda says its 2.2-liter i-CTDi diesel runs as cleanly as a gasoline engine, meeting EPA Tier II Bin 5 requirements.

By the way, Eaton has a similar system under development for heavy-duty truck engines facing stringent requirements coming in 2010. From what's been disclosed, Eaton's concept uses multiple components to generate and store the ammonia; by contrast, Honda's special feature appears to be its dual-layer catalyst.

Regen: Fwd Versus Rwd

It makes complete sense, but I never reasoned through the implications: Front brakes do most of the work in decelerating a car. (This is why they're sized larger and their pads generally wear quicker.) And, given this, the front wheels are better situated for a hybrid's regeneration of braking energy. That is, a front-wheel-drive hybrid can capture more braking energy than can its rear-wheel-drive counterpart. This is one reason fwd hybrids often post "reversed" city/highway results, their regen-enhanced city number higher than the highway mpg. By contrast, rwd hybrids are less likely to display this oddity.

Electric A/C

There are real advantages in an electrically driven air-conditioning compressor. First and foremost, it relieves the engine of a major parasitic drag. Second, as the unit doesn't need any belt drive, it offers packaging advantages underhood. Third, its size and operation are enhanced by being independent of engine speed.

By contrast, an engine-driven a/c compressor has to be sized for worst-case conditions, namely providing maximum cooling at engine idle. A similar situation exists for power-assisted steering, though its power requirement is considerably less than a/c's. In fact, we have electric steering-assist on many 12-volt cars. Alas, electric a/c requires a hybrid's high voltage.

This Is A Developing Story

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