high percentages of alcohol. I don't mean to crosspost from over on the NG900 & OG9-3 board but there are similar conversations taking place.

Certainly there are some tech/materials issues that need to be addressed with burning high percentages of alcohol for long periods of time, but the simple fact that the octane of ethanol is so very high makes it potentially a very good fuel for an SI (spark ignited) engine--in some ways better than gasoline.

Unfortunately, running ethanol in a standard CR (compression ratio) gasoline SI engine gives a pretty poor return because of the overall lower energy density per unit volume of alcohol compared to gasoline. But, when you start talking higher percentages of ethanol, the energy conversion efficiency begins to look much better because you can than begin to design engines that are optimized to run much much higher effective CR's. The link below shows a study where the energy conversion for alcohol in a high compression SI engine designed to run on alcohol can actually approach that of a diesel--which is somewhere in the neighborhood of 40% compared to somewhere around 25% for a standard gasoline SI.

My feeling is that we're in a pretty unique time when people are beginning to seriously consider alternative fuel sources and it will take more than a few years to see which technologies win. Right now I wouldn't place any bets against alcohol as more production synergies and partnerships are developed and optimized. It will be particularly interesting to see what happens in 2007 when subsidies are removed. Anyway, alcohol sure beats the pie in the sky future world of hydrogen powered everything that some envision. I hope I'm never in the situation where I strap my future wife and kids into a car with a 5000 to 10,000 PSI hydrogen canister mounted underneath.


posted by 67.10.240...

EPA SI Study

• Ethanol talk, MS, Thu, 20 Apr 2006 23:03:28
  • Don't overlook the efficiency gains allowed by burning, Drew in Houston, Sat, 22 Apr 2006 17:10:29 <-- Viewing This Message
    • Dawgone--wrong link above. That's a good one too, Drew in Houston, Sat, 22 Apr 2006 17:14:35
  • I have noticed that when I drive to different parts, Pat, Fri, 21 Apr 2006 08:34:36
  • Just saw something about it in the news, AdamB , Fri, 21 Apr 2006 06:26:17
    • Re: Anyone hear Science Friday last week?, AeroDave, Fri, 21 Apr 2006 06:39:33
      • Is there much refined gasoline going through pipelines?, saw, Fri, 21 Apr 2006 12:40:33
        • OK maybe that was a dumb question, saw, Fri, 21 Apr 2006 12:57:44
  • Skinny on what to expect?..., Chaz, Thu, 20 Apr 2006 23:33:10
    • good writeup on the future of E85, turbosaab , Fri, 21 Apr 2006 05:52:55
      • Indeed, No.9, Fri, 21 Apr 2006 06:50:57
    • Re: Skinny on what to expect?..., Ted Y, Fri, 21 Apr 2006 04:49:52
      • Please enlighten me, No.9, Fri, 21 Apr 2006 06:33:56
      • Um, did you really think that through?, ChipJ, Fri, 21 Apr 2006 05:09:47

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