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View Diary: Banning Oil:   Dimethyl ether, Hydrogen, Nuclear Power and Motor Fuel for Cars and Trucks. (45 comments)

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  •  I like your support of nuclear energy and lack of (2+ / 0-)
    Recommended by:
    besieged by bush, Jimdotz

    same for hydrogen, but I just don't get the DME deal. DME has a boiling point of -22 degrees celsius. Methanol has a boiling point of +64.7 celsius, a liquid at normal temperatures. It burns fine in lots of engines and is a great fuel cell fuel. From your diesel engine references, I suppose DME has a high cetane rating??

    Actually, speaking as a physicist who works on fuel cell R&D, I believe that our best bet 10+ years out would probably be nuclear-produced electricity and battery-powered cars. Seriously.

    Come see TV from the reality-based community at

    by MarkInSanFran on Fri Nov 24, 2006 at 05:43:23 PM PST

    •  The difference between DME and methanol (2+ / 0-)
      Recommended by:
      MarkInSanFran, SCFrog

      concerns the toxicity.

      DME is almost completely non-toxic whereas methanol is extremely toxic.  DME, for the record, is mostly used today a propellant in hairspray cans - where it has replaced CFCs.

      I have heard a lot of talk about methanol, and frankly it terrifies me, because a fuel spill could very easily destroy the utility of a reservoir, river or lake for quite a long time.

      Moreover it is next to impossible to remove methanol from water - in which it is miscible - whereas DME can be removed - if desired - by simple aeration.

      DME in contrast to hydrogen has a very high critical temperature, higher in fact than the boiling point of water.   Thus DME can be regarded as a liquid fuel.   The cetane number of DME is in the 55-60 range, whereas the cetane number of petroleum diesel is 40-55.

      The critical temperature of DME is 126.9C.   Thus it is readily accessible as a liquid in all climates, even Death Valley, under conditions of moderate pressure.   In its physical properties it's very much like propane, but, lacking carbon carbon bonds, is cleaner.

      The need for slight pressurization far outweighs the toxicity disadvantage for methanol.

      The physical properties of DME are discussed here:

      A very important fact that I have not discussed much is the atmospheric lifetime of DME, which is about 5 days.   This contrasts very well with methane, which has a lifetime on the order of decades.    This means that DME will not accumulate in the atmosphere if leaked and will exhibit no important greenhouse gas potential.

      Note that DME is not something that simply sounds good in theory.   Japan, China, and Sweden all plan huge DME infrastructures.   Other countries do as well.   Japan and China are building DME plants at a rapid pace even as we speak.   Japan will first use DME in its gas fired power plants, where it's use is already approved.   (This is initially a mechanism to make it possible to ship and store natural gas, from which much DME is now derived.)  China is building DME plants - regrettably - as a means of liquifaction of coal.

      •  So ... PRC plans to (0+ / 0-)

        go to 10% methanol don't excite you?

        My understanding is the Financial Times just had a story about PRC plans for 10% of its transportation fuels to be methanol by early in the next decade.

        •  Their methanol and DME infrastructure will (0+ / 0-)

          overlap.   The chinese are using - regrettably - coal reforming to make sythesis gas.   Under these conditions a mixture of methanol and DME is obtained.

          I worry too much about methanol toxicity.   A major spill could really do some very serious damage.   A DME spilll by contrast will just blow away quickly.

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