Saturday, April 7, 2012

Baby Acura

Looks like Honda's premium branded Acura division will be fielding a new vehicle that will use a combination of conventional IC power for the front wheels and twin motor electric propulsion for the rear wheels. This gets the vehicle all-wheel-drive while lowering the significantly expensive and weighty levels of componentry normally used to do this job. Acura plans to used a similar system in their upcoming sports car the NSX but the system will be reversed with the IC engine directly powering the rear wheels and the electric motors powering the front.

On the surface this setup sounds very capable but a deeper analysis reveals that it amounts to baby-steps. Obviously a generator of some sort is required to power the electric motors which adds signifcant weight to the setup. The reason I call this a baby-step is that if electric motors can be successfully used to power one end of the vehicle it's hard to see why they can not be used for both ends. This approach, which I have previously discussed here at some length, would result in weight reduction of as much as several hundred pounds and make all-wheel-drive, stability control, and traction control possible entirely by electronic means instead of relying on the substantial weight and complexity of the usual suite of mechanical whiz-bang required.

The power requirements in an all electric drive system can easily be split between four motors which obviate any need for a large and heavy centralized motor. What would be the most salient obstacle is the fact that powering these motors would require a generator equivalent in output to the internal-combustion powerplant driving it.

In the case of premium level sedans this means a generator capable of developing at least 300 horsepower which means that, even in the highest tech form available, such a device will be very heavy and extremely expensive. It is true that although the total weight of such a system could well be less than a fully mechanical one the total cost of such a system is another matter entirely. Even at the OEM level the motors could cost several thousand dollars each and the generator could easily cost as much as twenty thousand dollars. That is merely a guess about the generator which might well actually be far more expensive than that.

An additional consideration is that whatever powerplant used to power such a generator is unlikely to come straight off anyone's parts shelf. For maximum weight savings and efficiency levels the powerplant would have to be specifically designed for such duty and this means big development bucks--probably several hundred million dollars worth all told. Since such a system could likely only be contemplated for vehicles costing in excess of 50,000 dollars since the far lower sales levels of this vehicle class means each unit has to absorb a much bigger chunk of its development costs. Designed from scratch engine/generator combos are in development (http://oiukm32.blogspot.com/2009/09/lotus-land.html) but there has not been much of a rapid push towards such technology. The Lotus system is interesting but is of a quite low power level and I suspect that as power requirements increase costs would increase exponentially.

In short Acura is using this "new" setup primarily as a marketing tool and a somewhat less mechanically complex method of achieving all-wheel-drive. This can be construed as a technological "baby-step" but fielding an all electric drive system would be more in the vein of seven-league boots so it's hardly suprising they have done it the way they have.

It would really be inaccurate to call this notional direct drive IC/electric system a "hybrid" system. In all cases to date the term hybrid refers to the fact that the means used to drive the wheels is mechanically shared between conventional hardware with varying levels of electrical assist with the required juice supplied by batteries. The new Acura alters the equation by using a generator to supply power to the electric motors but the comparison still holds.

An internal-combustion engine directly powering a generator which directly powers the motors at the wheels is quite a different technological kettle of fish than any currently sold hybrid drivetrain. Whatever packaging, weight, and efficiency gains an IC/electric drive system might confer the generator cost issues are likely to mean that if it is implemented at all in the near term it will be on high end vehicles only.

Regarding the generator part of such a system a quick internet ramble reveals that a typical conventional 300 horsepower electric generator is ridiculously heavy and absurdly expensive. Of course a 100 HP generator might be more than adequate to power a vehicle since torque levels would be more than adequate for good acceleration but the vehicles top speed would still be limited to whatever the max power output of the generator might be.

All these numbers may have little to do with an actual automotive situation but there is absolutely no question that an engine/generator combo that could provided performance equivalent to a conventional 300 horsepower engine/transmission setup is going to be a frightening expensive proposition. It might be, on paper, a "good idea" but an idea that turns a $40,000 vehicle into an $80,000 one manifestly rockets the situation down far below "good" territory.

Sadly a device such as an ultra high-tech light-weight high output generator is not ever going to be subject to the production economies of scale that could alter this equation enough to court practicallity. All-wheel-drive for a pure electric battery powered vehicle is another matter but of course there the so far intractable bugaboo is the horrific expense and weight of high capacity batteries regardless of how technologically advanced they are. For this reason all electric battery powered vehicles will remain little more than a halo products and showroom traffic builders, at best, for manufacturers that, with microscopic sales levels, will contribute little or nothing to overall fleet efficiency for the foreseeable future.

Add up the sales of Tesla and Fisker, multiply times ten, and the result is a sales volume that any major manufacturer would count as a serious failure. We don't have to only consider overpriced niche vehicles to see true market forces at work. Case in point is the Chevy Volt which will never, I repeat never, recoup its development costs or save its owners so much as a skinny penny durring its service lifetime.

Indeed I supect vehicles will be powered by dilithium crystals or some other as yet undreamed of power source before battery power becomes anything more than a practically useless icon of misguided green activism. The dreams of battery powered eco-fabulousness continue to run seriously afoul of simple arithmatic. Insisting that two plus two may not now equal seven but gosh darn it with enough "investment" someday it surely will barely merits the status of wishful thinking.

Acura, and most other manufacturers, are taking baby-steps because much bigger steps do not hold out serious improvements in efficiency or cost. Unlike green activists arithmatic is an inescapable part of their existences. The continued cry that we simply must "do something" to avert sauteeing the planet should in no way mean that we "must" do manifestly pointless and counterproductive things that merely serve to do economic violence to consumers and allow activists to indulge in smug eco-preening.

Electric vehicles have been the "next big thing" for a century and the next century is likely to maintain that status. The marriage of conventional powerplants and electric drive systems holds more promise but only just barely.

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