Dave's Energy

Saturday, December 17, 2005

Fischer-Tropsch diesel

Interesting article on F-T diesel. I'm amazed at the extremely low aromatic content of the resulting fuel (<3%), which is key to reducing soot/UHC emissions. And the high concentration of parafins gives the fuel a nice, high cetane number. However, in producing gasoline, they'll need to reduce the level of parafins in order to boost the octane number, but this isn't difficult.

4 Comments:

  • Indeed, gasoline could be a next step, but clean diesel would be the application that makes the technology initially worthy of global expansion. Lowering the SOx and NOx emmissions seems to be the primary target for most countries that are trying to make their diesel more enviro-friendly. In that sense, the FT fuels fit the bill nicely. That is why I have been bullish on the potential for GTL-derived clean diesel to replace a meaningful chunk of the world's transportation fuels. And yet, two things struck me in this article:

    1) the overall CO2 output of the entire process increases compared to crude oil refining (it merely displaces the CO2 production from the car to the refinery).

    2) Cobalt is the main catalyst (not iron) for the low-temp SSPD process most likely to be used by Sasol. Cobalt is also the catalyst in the BP-synfuels process and also the Syntroleum process. Cobalt is also used in the production of Nickel Metal Hydride (NIMH) batteries for hybrid vehicles. So, are we exchanging our crude oil shortage for a cobalt shortage?

    By Blogger Dave Anderson, at 4:06 PM  

  • Good point about the CO2, sometimes folks forget to take a "well-to-wheels" approach. Unfortunately, "conservation of atoms" requires that all carbon in a fuel eventually end up as CO2, one way or another. A small amount of carbon might also end up as CO and soot, but this essentially wastes some of the energy potential of the fuel, so total conversion to CO2 is a best-case. Therefore, regardless of how the fuel is produced, refined, processed, combusted, etc. you still end up with the same amount of CO2 at the end, even if not all of the CO2 is emitted from the tailpipe.

    By Blogger David Horning, at 8:49 PM  

  • Hmmm...interesting. So maybe we should focus more on carbon sequestration opportunities?

    By Blogger Dave Anderson, at 7:01 AM  

  • That's one solution. Another possibility is fuels that have less carbon to start with - i.e., fuels with a high hydrogen-to-carbon ratio, like NG, ethanol, methanol. Of course, H2 is ideal from this perspective, with no CO2 emissions. Unfortunately, since there aren’t any naturally occurring H2 reserves, energy is required to produce it in the first place (from NG or water) so I don't think H2 is the answer. Plus, from an internal combustion engine perspective, H2 is really tough to work with.

    By Blogger David Horning, at 8:25 PM  

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