Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: Petrochemicals on 27/05/2023 00:21:50
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The liquid fueled Ice has fantastic advantages over solid or gaseous counterparts, two of which are the fuel is easily managed and waste products are gaseous. Unfortunately the fuel used is not renewable generally.
The atmosphere generally has 2 gasses in it, oxygen (~20~%)and nitrogen at around 80, along with varoius other small amounts of other substances. It strikes me it would be beneficial that these 2 gasses would make ideal waste products of any renewable energy storage cycle. Would it be possible to make a liquid fuel from them?
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When you combine nitrogen and oxygen into various compounds (whether it be nitrogen dioxide, dinitrogen tetroxide or dinitrogen pentoxide), what you get is generally an oxidizing agent and not a reducing agent. If you want to make something you can burn, you could potentially combine the hydrogen from water with the nitrogen in air to produce something flammable like hydrazine. From what I understand, that's not a very fun chemical to be around, though.
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Hydrazine is a moderately stable rocket fuel and can be burned in a ramjet.
When the atmospheric CO2 level reaches 1 - 2% it will be worthwhile using nitrogen, carbon dioxide and water to synthesise ethanol and nitrous oxide, then resurrecting the internal combustion engine and enjoying a drag race. Above 2% you will begin to lose the audience.
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It's "sort of" being done, at least on an experimental scale.
The "missing bit" from PC's idea is anything that would actually work as a fuel "Just add hydrogen"
https://www.frontiersin.org/articles/10.3389/fmech.2022.944201/full
Hypothetically, with the right catalyst, the oxygen and nitrogen would combine exothermically with water to form nitric acid.
That's not my idea of environmentally benign.
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Ammonia will burn exothermically with oxygen producing the innocuous water and nitrogen gas. It is a lot safer than hydrazine( which can decompose exothermically in the absence of oxygen ) but a lot less energetic. All these are just energy carriers and do not solve our energy problem as the energy to produce them is still required.
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The joy of ammonia as a fuel is that it doesn't use carbon (which some folk find unacceptable), can be manufactured biologically (i.e at low temperature and powered by sunlight) and whilst it has only 40% of the energy density of diesel, that is still 100 times that of a battery and a road vehicle can be refuelled at around 100 MW (say 3 minutes for 500 mile range) with a conventional-ish pump, compared with a maximum of around 400 kW for a battery (average 40 minutes,if you can find a working charger and don't mind shortening the battery life) so doesn't require significant infrastructure investment.
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Another advantage of ammonia as a fuel is that it doesn't need compression/refrigeration to anywhere near the same extent as hydrogen or methane for easy transport.
- Ammonia boiling point: -33C at atmospheric pressure
- Methane boiling point: -161C "
- Hydrogen boiling point: -253C "
Ammonia is a feedstock for biological systems, but toxicity is a problem at high concentrations....
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So the sane choice for future transport is either hydrogen (distributed as a gas through the existing 150 bar grid) or ammonia (distributed as a liquid, through the existing LPG tanker network) and burned in a modified internal combustion engine, a turbine, or a fuel cell. None of which requires digging up roads to install a whole new grid, disenfranchising those who don't have a front driveway, building new car parks to accommodate the queue at a motorway charging station, or lugging a ton of dead battery around the country.
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toxicity is a problem at high concentrations
Not if you are comparing it to lead-acid or lithium batteries.
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When you combine nitrogen and oxygen into various compounds (whether it be nitrogen dioxide, dinitrogen tetroxide or dinitrogen pentoxide), what you get is generally an oxidizing agent and not a reducing agent. If you want to make something you can burn, you could potentially combine the hydrogen from water with the nitrogen in air to produce something flammable like hydrazine. From what I understand, that's not a very fun chemical to be around, though.
Yes water would be an easily avaliable recyclable material. I suppose if you could make oxidiser too that would be another way of storing energy.
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There's plenty of oxidiser in the ambient air. Green plants make it and I use it all the time.