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Ammonia as Fuel

Craig ShieldsPosted on Posted in Energy Storage
Ammonia as Fuel

During my interview with Matt Simmons on “peak oil” for my book on renewables, I asked about suggestions for averting the imminent disaster he sees associated with maintain the status quo in energy generation and consumption. The response:

Large wind turbines will soon be built at the University of Maine and tested off the Maine coast, made from advanced composites with breakthrough characteristics in strength, weight, and cost. Once put into production, they can be used to produce large quantities of ammonia.

Matt pointed out that anhydrous ammonia (NH3), also known as “the other hydrogen,” is ultra-clean and energy-dense — the closest thing to a perfect transportation fuel.

He laid out a significant list of benefits:

  • Liquid at ambient temperatures and moderate pressures (~125 psi)
  • Has 52% of the energy density of gasoline, more than 50% more energy dense than liquid hydrogen
  • Can be used directly in internal combustion engines, using relatively straightforward conversions of gasoline and diesel ICEs
  • Easy to store and deliver in large quantities
  • Current worldwide annual production of ammonia is ~130 million tons
  • A storage and delivery infrastructure of pipelines, barges, rail and truck already exists for ammonia, with 3000 miles of pipeline in the US heartland; retail ammonia outlets exist in almost every state
  • Can be produced cleanly from coal and natural gas with carbon sequestration, and also from biomass, renewable energy sources and nuclear power, using nitrogen from the air
  • Contains no carbon, so releases no GHGs on combustion; also any NOx is easily neutralized

I propose to conduct a bit more research on this subject, and post my findings when they are available. In the meanwhile, please feel free to comment.

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13 comments on “Ammonia as Fuel”
  1. Larry Lemmert says:
    January 9, 2010 at 1:34 pm

    Ammonia as a fuel does not make a whole lot of sense. First, like hydrogen, it is not a source of energy but a mere transfer of energy medium. That is not really bad in itself since transformation is a necessity for virtually all of the actual root sources of energy.
    The problem with ammonia is in its use as a fuel. It burns well with a good energy output but the byproducts of combustion are the various nitrogen oxides (NOx) and water. While NOx can be neutralized to make a nitrate fertilizer, the burden of carrying the neutralizing agent, an acid, in large quantities, and then the storage requirement for the resulting fertilizer solution becomes a literal burden.
    Hydrogen serves the same nitche as ammonia with fewer drawbacks. I am not a proponent of a hydrogen economy by any means but ammonia would be further down the list of choices when hydrocarbons are phased out. Electric vehicles with battery storage is at the top of my personal list.
    Larry L

  2. Larry Lemmert says:
    January 9, 2010 at 1:42 pm

    Oops. Neutralization of NOx would be with a base, not an acid.

  3. David Nugent says:
    February 26, 2010 at 5:28 pm

    It is right to highlight the possibility that NH3 combustion engines will produce NOx emissions. The solution to this problem is well known and documented. I am referring of course to Selective Catalytic Reduction according to the forward reactions:

    4 NO + 4 NH3 + O2 >>  4N2+6 H2O (1)
    6 NO2 + 8 NH3  >> 7 N2 + 12 H2O (2)

    SCR is already used to minimise NOx emissions in diesel engines. Where do they get the NH3 from? Either be decarbonating urea or by reforming fuel to produce H2, which is then combined with atmospheric nitrogen in a mini Haber Bosch reactor.

    http://en.wikipedia.org/wiki/Selective_catalytic_reduction

    This problem is trivial for a NH3 engine since the exhaust need only be bubbled through the fuel tank. No, I don’t mean this literally, but you get the idea.

    Hope this helps.

    D.

    PS: You might want to read this report I wrote back in 2007, and published in 2008. Downloadable here:

    http://www.elucidare.co.uk/for-media.php

    • Craig Shields says:
      February 27, 2010 at 12:45 pm

      Yes, this helps a great deal. That’s a fantastic report you have online, btw. Thanks very much.

      In addition to great content, I love the way you British scholars write. You use “candidature” rather than “candidacy.” Fantastic!

  4. bill northlich says:
    June 3, 2010 at 9:57 am

    Larry L. …er – where do you think the electricity for “electric vehicles” comes from?

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  7. Frank Eggers says:
    April 10, 2012 at 5:21 pm

    NH3 for use as motor fuel is not without problems, but probably the problems could be easily solved. An important advantage over H2 is that it can be liquified at normal temperatures and convenient pressures, unlike H2. For that reason, it makes more sense than H2.

    To run well on NH3, an engine would have to be designed for it from the ground up. NN3 is more difficult to ignite than gasoline which can cause missing, but spark plugs with a much larger gap and an ignition system that could deliver a longer duration spark would probably solve that problem.

    Also, NH3 burns much more slowly than gasoline. That problem could be solved by 1) designing an engine to run at a lower speed, 2) designing an engine with a longer stroke so that the combustion chamber would be more compact thereby shortening the flame travel, 3) designing the engine so that there would be more turbulence in the combustion chamber thereby speeding up combustion, 4) having multiple spark plugs per cylinder if necessary, and 5) heavily turbo-charging the engine so that the power would be adequate in spite of the lower speed (than could be done because NH3 has much greater anti-knock characteristics than gasoline).

    The engine would have to be kept tuned properly because missing would cause unburned NH3 to be ejected from the exhaust system; not pleasant! Also, special fueling techniques would have to be used to prevent NH3 from escaping while filling the tank. As explained by another poster, NOx emissions could easily be dealt with.

    Probably all these problems could be solved without undo difficulty.

    The NH3 could be produced by energy from wind turbines and, because the NH3 need not be used immediately upon production, the intermittent problems of wind energy would not be a serious problem. However, unless wind energy could be produced more cheaply than now, it might not be economical.

    In situations where battery electric vehicles would have inadequate range, running vehicles on H3 would be a possible solution. It might even turn out to be more practical than running vehicles on batteries; we don’t yet know.

    When changing energy technologies, it can take considerable time to determine which is the best path. When railroads converted from steam to Diesel, it took years to evaluate the economics and determine that Diesel was more economical. Evaluating the economics of energy systems that don’t use fossil fuels could be just as difficult.

  8. jonathan hosseini says:
    August 15, 2012 at 3:37 pm

    Great Discussion Thread. Thank you.

1 Pings/Trackbacks for "Ammonia as Fuel"
  1. Ammonia–Fuel of the Future? « Biofuels Seminar says:
    January 30, 2010 at 7:53 pm

    […] is the inevitable by-product of NOx, a large contributor to the formation of smog. Despite this, the benefits of ammonia use as a fuel source may still outweigh the negatives. It has already been show to work in a vehicle […]