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Lemons into Lemonade, Martian-style

Discussion in 'SpaceX' started by AudubonB, Oct 21, 2016.

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  1. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Oak Ridge National Laboratories has just demonstrated what appears to be a

    1. Efficient ("65 - 73% efficient, and consuming just 1.2 volts") - whatever that means, and

    2. Operable at STP (although the "T" in STP is Terran T, not Martian T)

    mechanism for turning CO2 into ethanol.

    Drink up! Or refuel your spacecraft!

    Now, those down-to-earth types at ORNL have their sights only on solutions to global warming, but I thought it appropriate also to consider Martian warming...

    Link here:High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode - Song - 2016 - ChemistrySelect - Wiley Online Library
     
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  2. Genshi

    Genshi ermagerd, I lost mah reservation!

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    I read a somewhat more accessible link about this on Phys.org. I'm wondering how well it will scale and how easily the catalyst can be produced. If it does scale well, and it really is as efficient as they say, this looks at first blush like a decent option for terrestrial carbon capture.
     
  3. macpacheco

    macpacheco Member

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    #3 macpacheco, May 16, 2017
    Last edited: May 16, 2017
    This is an amazing discovery, if the fossil fuel people doesn't kill it.
    USA gasoline is mixed with 10-15% ethanol. It reduces emissions. That's where the whole ethanol discussion in the USA ends, cause the fossil fuel interests don't want it to be taken further.
    There is off the shelf technology, already implemented in at least 5% of the existing worldwide vehicle fleet. Its called flex fuel cars. It enables cars to run on ANY mix from 100% gasoline to 100% ethanol. Brazilian gasoline is typically 15-25% ethanol. USA gasoline is 10-15% ethanol. Here in Brazil you can find the natural ethanol produced at the stills in nearly every gas station. In the USA there's E85, ethanol has most of its water content removed and 15% gasoline is added.
    If this reaction can produce Ethanol even at twice the cost of current ethanol, but in a way that it can be easily turned on and off as often as necessary, the dilema of having too much wind/too much solar in the grid is shot to smithereens. All excess power is dynamically consumed by making ethanol. With enough excess solar/wind, it might be possible to offset 100% of gasoline consumption with ethanol and put the first nail on the oil death coffin.

    The fundamental key aspect of flex fuel technology is its cheap, it doesn't increase the cost of cars not even by 5%, so it can be the gateway from fossil fuels to a 100% green fleet, with a mix of ethanol (specially interesting would be a Volt/Prius that burns ethanol instead of gasoline) and BEVs.

    Ethanol has one more interesting advantage. Same displacement ethanol engines produce more power. The disadvantage is the cheap ethanol that's mixed with 25% water is lower energy density than gasoline (you'll need a bigger tank for the same range). I think E85 avoids that problem, since it removes the water and adds 15% gasoline to Ethanol.
    Another very interesting characteristic of Ethanol. Its freezing point is -115C (something like -150F) so or all practical purposes, it never freezes (as long as its pure Ethanol). At the same time, gasoline and diesel freezes in temperature found in Minnesota and Canada.

    At least 90% of gasoline cars in Brazil are flex fuel cars. The technology also allows for burning natural gas, but in the case of gas, you need separate gas tank and gas piping to the engine since its a gas instead of a liquid, duh ! Brazil uses compressed natural gas, which is cheaper to make than the USA standard liquified natural gas (more energy dense but more energetically expensive to make).
     
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  4. macpacheco

    macpacheco Member

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    #4 macpacheco, May 16, 2017
    Last edited: May 16, 2017
    Ethanol isn't really a viable way to store carbon long term. Its a liquid that evaporates way too easily vs gasoline. You need a solid instead.
    But it is a nearly drop in replacement to gasoline. 90% of Brazilian cars produced in the last 15 years have this tech called Flex Fuel. Our gasoline is normally 25% ethanol. We can buy ethanol at our gas stations. The key reason Brazil didn't go all the way to ethanol is oil prices dropped and we don't have enough ethanol production to replace all gasoline consumption.
    The USA has E85, but in the USA ethanol is made with Corn, mostly the Corn starch. Brazil makes ethanol from sugar cane, which is mostly sucrose, a direct feed to the bacteria that make ethanol. Its somewhat like comparing BEVs with FCVs, the energy efficiency of making Ethanol from sugar cane is much, much higher than from corn.
    But with this reaction, the game changes. Make ethanol from solar and wind instead ! Ethanol can be stored for years, so excess Ethanol can be produced in the summer from excess solar and from wind in the winter.
    The interesting question is how efficient it is to extract CO2 from the oceans/air to feed this reaction. Probably easier to locate ethanol producing facilities near fossil fuel power plants and directly pipe the CO2 rich exhaust into the water tanks !
    This might be the key to eliminating the energy storage challenge with too much solar/wind in the grid. Just make ethanol only when the grid is over supplied. Make ethanol from excess solar in the summer day, from excess wind production, and even from excess base load power every night. The latter sounds stupid, but lets not ignore the fact that the grid will need significant baseload generation for a long time until battery storage finally reaches TWh/yr in production and big cities get tens of GWh in grid storage.
    As much as I love EVs, we can't ignore the advantage of simply going nuts with solar and making Ethanol from the excess energy. If this can be demonstrated economically, it would 100%, positively silence every rational anti solar person out there.
     
  5. jkn

    jkn Member

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    Diesel does freeze. Diesel sold during winter is different than during summer to reduce risk. I have never heard gasoline freezing. What do you put into it?
     
  6. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Awww, lay off poor macpacheco. To a brasileiro, any time anything is under +10ºC it stands to reason it just has to be rock solid.
     
  7. macpacheco

    macpacheco Member

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    Well I have lived in the USA for over 7 years, and I've experienced first hand several weeks at Minneapolis, Chicago, NH and upstate NY (each) at the peak of winter. I flew all over your nice but sometimes very cold country in the 90s.
    Gasoline doesn't tend to freeze cause there are different formulations for USA gasoline, in the summer and in the winter, and depending on where you buy it. In Miami gasoline is likely all the same year around.
    Winter gasoline has anti freeze agents. Pure gasoline does freeze in very cold temps found in Minneapolis, Chicago and all over Canada in the winter. A quick google search says gasoline freezes between -40C and -50C.
    If you keep your summer gasoline in MN until winter, you might get a nasty surprise.
    I heard about this freezing issues because there are some aviation engines designed to run on Diesel or JetA. The key difference is JetA is much harder to freeze, while Diesel isn't, plus the sulfur content on standard Diesel.
     
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  8. jkn

    jkn Member

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    Winter gasoline has lower boiling point than summer version. Otherwise car would not start. So it's difficult in practice, but gasoline could freeze in north. (Diesel becomes unfilterable in cold. I don't know if it actually freezes solid.)
     
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