THE HIGH COMPRESSION GAMBIT

October 16, 2012 § 7 Comments

The foremost American electric car battery company, A123, declared bankruptcy today.  A high flying MIT spinoff, honored by the President at the big house, bestowed with DOE funding to the tune of over $200 million, is on skid row.  I am sure the Pundits will weigh in with what this might mean.  But it certainly is a datum point that fits in with the lackadaisical sales performance of the electric cars.  And it appears to offer support for what I am dubbing The High Compression Gambit by Mazda.

Mazda has made a few moves that signal an explicit strategy to defer electrification to the future.  They have introduced a line of cars with high compression ratios operating on conventional gasoline.  In my book, Shale Gas: the Promise and the Peril, I advocate the design of  high compression engines to take advantage of the high octane ratings of the three viable gasoline substitutes, ethanol, methanol and methane.  I suggest piloting through the armed forces, a la the Hummer.  It seems as if at least one company is willing to take the plunge and not wait for anyone to lead the way.

But Mazda’s move appears to have nothing to do with enabling the gasoline alternatives.  More below on how we can avail of that, no matter their intent.  They were shooting for higher engine efficiencies to enable the latest CAFÉ standard to be met.  Since the design started years ago, somebody was reading excellent tea leaves.

Conventional gasoline fueled cars have compression ratios (CR) of around 9:1.  For a discussion of this parameter, see a previous blog.  Regular gasoline experiences premature fuel ignition at higher compressions.  What Mazda did was to make the cylinder narrower and longer.  But the critical innovation was to provide two injections of fuel during a single cycle.  The second injection is right at the point incipient knocking.  The evaporative cooling drops the temperature enough to prevent premature ignition.  This allowed them to increase the CR to 12:1.  Fancy exhaust system management allows them to another notch up to 13:1.  For 14:1 they need to use premium gasoline.  They are offering this only in Europe.  They believe American consumers will balk at the fuel premium, which is around 30 cents in most states.

The Mazda3, offered with just the junior version of 12:1 is reported to improve mileage from the 24/31 City/Highway to 29/39.  There is some arm waving on manual versus automatic transmissions, improvements to the latter, and so on.  But these are big improvements with no change in the gasoline.  This appears to be the gambit.  Keep improving the efficiency of the engine to help with the CAFÉ targets and kick in the electric capability when things get more viable.

We have opined in earlier blogs that electric cars, and hybrids for that matter, needed battery costs to drop to under $200/KWh and range to improve.  The demise of A123 is not a promising note, but they may still be a factor.  Continental Airlines went bankrupt twice before it became a value leader.

As we have noted before in these pages, improving efficiency is the fastest way to reduce emissions.  The same gratification for less fuel used.  I was not able to locate the predicted mileage for a Mazda3 with CR of 14:1.  The benefits diminish in non-linear fashion at the higher CR’s.  But it needs 95 octane gasoline.

Now for the punch line.  Both E85 and M85, respectively with 85% ethanol and methanol, rest gasoline, will certainly do the job.  My favorite is methanol.  The evaporative cooling with M85 will be even more effective than with gasoline.  In fact, compression ratios of 16 or 17 ought to be possible. Also, it is dramatically cheaper with low cost shale gas and can also be made from coal or biomass, all for lower cost than ethanol from corn.  At today’s natural gas prices the cost of methanol is under 45 cents per gallon.  With half the energy content of gasoline it is still much cheaper.

So, consider that at today’s regular gasoline price of $3.80, a compact car will have a fuel cost of 10.8 cents per mile (35 mpg assumed).  With the same assumptions on range, M85 today will cost 5.8 cents per mile.  Because of the units we are using, the energy content penalty of methanol is already counted. The consumer would have to refuel every 200 miles instead of the 350 miles assumed for the gasoline case.

For the CR 14:1 vehicle the comparison would be with premium gasoline.  That would raise the cost per mile to about 11.7 cents, while the M85 would remain the same because the 15% gasoline component need only be regular gasoline.

If M85 were available, Mazda could bring the 14:1 car to this country, make the small modifications required to tolerate ethanol and methanol, and allow consumer choice.  The driver could use premium gasoline or E85 or M85, whichever was available.  Obviously, at the numbers shown above they would demand M85.  This would set the ball rolling for the true future: some portion of passenger vehicles with CR’s of 17 running on M85 and many others with CR’s of 14 or so with fuel choice.  Oil derived gasoline would be rendered just another option, a step towards reducing oil to merely a useful, not a strategic, commodity.  When that happens, OPEC will be defanged as a manipulator of oil price.

Vikram Rao

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§ 7 Responses to THE HIGH COMPRESSION GAMBIT

  • Steven Warwick says:

    The most exciting development in this space is what Volkswagen is doing with diesel. 84 mpg pretty much changes the entire economic perspective.

    The best versions are on sale in Europe.

    There is a sense that the auto manufacturers are reluctant to offer diesel as the us is gaga over hybrids.
    http://content.usatoday.com/communities/driveon/post/2012/05/84-mpg-couple-drives-vw-passat-diesel-record-chevrolet-cruze-/1#.UH6c7MIpDFo

    • rtecrtp says:

      Steven: There is no doubt that diesel is one way to get higher mileage. But that anecdote you cited is a very unusual situation. The mpg expectations in normal driving are in the thirties.

      Diesel has more calories than gasoline and runs on higher compression ratios. But it is still derived from oil. Methanol can be from domestic gas or biomass. So, a high compression engine with efficiency rivaling diesel appears to be a better alternative. In fairness, synthetic diesel from domestic gas or biomass is feasible. However, using current technology, it will be more costly than methanol.

      Vikram Rao

    • Mark J Creager says:

      Everyone seems to forget that in 1979 Subaru made a car that F model that got over 55 miles to the gallon on a compression ratio of 9.7 to 1. I know for a fact because at 19 years old I bought one off the showroom floor and drove it for 13 years until I hit a deer. No one seems to remember that in 1980 Subaru had a car that got over 70 miles a gallon but the United States refused to let it be sold in the United States. Electronic fuel injection is really inefficient, that car I bought was a carburetor. There was a long throat tunnel that mixed the air and fuel into a perfect vapor form on the Subaru. Everyone seems to forget that liquid doesn’t burn, only the vapor. Fuel injection squirts liquid into the chamber, a bunch of it remains unburned because it’s still little Globs of liquid. People tend to forget or don’t even realize that a catalytic converter has one job and one job only, to finish burning the unburned fuel! Experimental vehicles with only one fuel injector and a long throat tunnel to each cylinder with gyrations and perturbations in the air channel to mix and break up the globules into vapor have been done and these cars get in the high eighties for fuel efficiency and miles per gallon. And we’re not talking smart cars, we’re talking 3000 pound cars. Speaking of the so-called smart car few people realize that the original got 84 miles to the gallon and then after governments and other agencies have gotten hold of it the poor car can barely eat out 42 miles to the gallon. My 2016 Jetta gets that on regular unleaded in Utah and I would rather drive my Jetta, than a shoebox smart car!

  • Vikram, I simply don’t think that shale gas is going to be the answer! Once they open those exporting stations and when any significant portion of the transportation fleet is switched to NG (or other fuels derived from NG, the cost advantage is going to go away!

    The 100 or 200 year supply is also not going to hold up when we start exporting LNG. So, in the long run, we’re just kicking the can down the road while thinking that NG is going to save us!

    Throw in a aquifer contamination or a moderate or worse earthquake and fracking might come to an abrupt end even sooner!

    • rtecrtp says:

      The nice thing about methanol as a gasoline substitute is that it does not rely on natural gas as raw material. If indeed natural gas prices go up for the reasons you mention, coal and biomass will kick in as more cost effective.

      Vikram

      • My question on biomass is, is there enough of it to fuel our transportation fleet? Especially without putting pressure on food production.

        I’ve also read that the carbon emissions of biofuels, especially when fertilizers are used is more than it saves?? I realize that the industry is young and will get better, but it seems to me that people are wishing for the best and just accepting that it’s going to work out.

        Coal, is dirty and unhealthy in a bunch of different ways and my gut level is that we simply need to walk away from it.

        It will be interesting to watch how this plays out.

  • Mark Corigliano says:

    We need to make fuels from non-food sources and produce cellulosic ethanol. Crops will be bio-engineered to maximize energy density. Keep an eye out for the first real commercial scale cellulosic plant in Sampson County built by Chemtex.

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