Carbon-free shipping – using renewables to create ammonia by electrolysis during peak periods to be used as shipping or aviation fuel

Carbon-free shipping. (Ed. – ammonia makes a very good aviation fuel)

Ammonia (NH3) could be used as a carbon free fuel for shipping. It could be made from atmospheric nitrogen combined with renewable energy derived hydrogen. Ammonia’s hydrogen could react with oxygen to power engines, turbines or fuel cells, emitting N and H2O. Oxygen pre-separation might be considered, instead of air, if it could raise energy conversion efficiency enough to warrant its use

Wikipedia’s http://en.wikipedia.org/wiki/Ammonia describes ammonia.

Hydrogen for ammonia synthesis should be obtained by electrolysis, rather than from methane. Apart from avoiding carbon dioxide emission, electrolytic hydrogen could avoid natural gas impurities which might harm fuel cells.

Compared with land-transport, ships should offer more space for ammonia safety features. With ammonia gas being lighter than air, leakage could be guided to high outlet vents. Storage tanks could be double walled with ammonia leak detectors between walls. Anhydrous ammonia could be stored under pressure as a liquid. It might be worth investigating strong ammonia aqueous solutions.

Ammonia powered shipping schemes could expedite domestic renewable energy deployment by mopping up surplus renewable energy generation at times of renewable energy over-supply, using planned redundant ammonia production and storage capacity. Stored ammonia could generate electricity when renewable energy supplies are low. Increased ammonia demand at overseas ports could encourage worldwide renewable energy deployment.

Peter Ravine

3 comments on “Carbon-free shipping – using renewables to create ammonia by electrolysis during peak periods to be used as shipping or aviation fuel

  1. Hydrogen, Methane and Ammonia are all candidates for ‘green gas’ technology. How about comparison? e.g.
    METHANE from anaerobic digestion is ‘green’. It can be added to natural gas much like ethanol to petrol. It can go to powerstations, and homes in current pipes. it can generate electricty in SiO fuel cell at 60% efficiency with the waste heat heating hot water. Compressed to 350 bar you can run a car on it 100 miles or so.
    HYDROGEN from electrolysers OR gasifiaction of biomass is also ‘green’. It too can be carried in existing pipes, and used in a wide range of fuel cells, including PEM for vehicles. I suspect fuel cells reach highest efficiency with hydrogen. Compressed hydrogen can also run an almost convetional car 100 miles or so. A mix of 7% or so could be added to natural gas with no need to modify end user equipment.
    AMMONIA must be more expensive to produce than hydrogen, because hydrogen is an ‘ingredient’. I suspect that the choice of fuel cells is more limited. I doubt it can be carried in current infrastructure. Its main advantage is it easy compression to a liquid. Or have I missed soemthing?

    This is ‘off the top of my head’! We need a much more thorough comparison.

  2. Thanks Dave for your much appreciated help.

    I have reservations about advocating ammonia for aircraft at this stage.

    The energy content for ammonia is far less than for current aircraft fuels. It could result in significantly lower flying ranges or payloads. It seems prudent to first gain widespread acceptance in using it for power generation and as a transport fuel under simpler conditions, such as for shipping, where energy density is less critical and where risks of ruptured tanks from high speed accidents are much lower.

    I imagine that oil, gas, coal and nuclear giants are worried about renewable energy liquid fuels prospects. They seem to have infiltrated Government bodies investigating the subject. http://www.hydrogen.energy.gov/pdfs/nh3_paper.pdf is a US government report which appears to be mainly a hatchet job against using ammonia as a fuel. It emphasizes ammonia toxicity with hardly any reference to the many millions of tons of ammonia handled safely worldwide over most of the last century.

    Regards, Peter.

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