Carbon neutral synthetic fuels

Discussion of coal, oil, gas, solar, wind, ethanol, energy policy, and global warming.
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nipo
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Re: Carbon neutral synthetic fuels

Post by nipo » Aug 12, 2018 8:03 am

I see that the problem of primary energy can be solved with generation IV nuclear reactors, later possibly with nuclear fusion, and even later with what ever. I won't continue explaining that primary energy side further, because this whole discussion forum revolves mostly around that topic.

Carbon, on the other hand, is the other interesting problem.

The simplified solution would be harvesting biomass and take all the needed carbon from biomass, and that would be it. Except that it is not nearly enough. Also, a fine fact is that we don't want to consume all biomass. We need it to keep this planet alive.

Inherently carbon neutral fuels exist, such as hydrogen and hydrazine, but they are either impractical or too dangerous (toxic) for most purposes.

Either we continue extracting carbon from underground reserves (coal, oil and natural gas) or else we choose circulating carbon by extracting carbon dioxide from oceans or atmosphere or both, which is the carbon neutral option.

The demand of carbon neutrality means that we shall extract carbon dioxide from sea water or atmosphere.
Transuranic heavy elements may not be used where there is life.
– Sapphire & Steel intro

modifiedgenes
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Re: Carbon neutral synthetic fuels

Post by modifiedgenes » Nov 03, 2018 6:13 am

E Ireland wrote:
modifiedgenes wrote:
E Ireland wrote:If you fire calcium carbonate in an electrical furnace you produce a nice concentrated stream of near pure carbon dioxide.

You can then spread the lime produced out on the ground or into the sea where it will react with atmospheric or oceanic carbon dioxide.
No need for enormous collection infrastructure.
You could not pay me enough money to go handling calcium oxide and spreading it.
Luckily farmers already spread quick and slaked line in enormous quantities!
The bulk of the stuff around here is plain calcium carbonate dug straight out of the ground. I don't think it is economic to heat the material up any longer for the gain in neutralising value.

jagdish
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Re: Carbon neutral synthetic fuels

Post by jagdish » Nov 07, 2018 1:43 am

nipo wrote:I see that the problem of primary energy can be solved with generation IV nuclear reactors, later possibly with nuclear fusion, and even later with what ever. I won't continue explaining that primary energy side further, because this whole discussion forum revolves mostly around that topic.

Carbon, on the other hand, is the other interesting problem.

The simplified solution would be harvesting biomass and take all the needed carbon from biomass, and that would be it. Except that it is not nearly enough. Also, a fine fact is that we don't want to consume all biomass. We need it to keep this planet alive.

Inherently carbon neutral fuels exist, such as hydrogen and hydrazine, but they are either impractical or too dangerous (toxic) for most purposes.

Either we continue extracting carbon from underground reserves (coal, oil and natural gas) or else we choose circulating carbon by extracting carbon dioxide from oceans or atmosphere or both, which is the carbon neutral option.

The demand of carbon neutrality means that we shall extract carbon dioxide from sea water or atmosphere.
I basically agree with the idea.
We could use high efficiency solid oxide fuel cells and avoid vehicle exhausts, the villain in present technology. It will work with reduced biomass quantities.


jagdish
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Re: Carbon neutral synthetic fuels

Post by jagdish » Jan 02, 2019 8:36 am

Hydrogen is an inconvenient gas fuel. Methanol/ ethanol with solid oxide fuel cells could be minimum CO2 producing per electrical unit arrangement.

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robert.hargraves
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Re: Carbon neutral synthetic fuels

Post by robert.hargraves » Jan 02, 2019 3:10 pm

I, too, got interested in the rotary engine for hydrogen. However the efficiency is only about 25%, about half achievable with fuel cells and electric motors.

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nipo
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Re: Carbon neutral synthetic fuels

Post by nipo » Jan 31, 2019 1:03 pm

I read about research on ammonia as a fuel for internal combustion engines, especially piston engines. Ammonia is carbonless and may be produced anywhere if relatively inexpensive primary energy is available.

There are two problems about ammonia:
  • Toxicity. Ammonia is seriously toxic. Especially an ammonia leak indoors is dangerous. Outdoors the situatiuoon is different because ammonia is also lift gas, i.e. lighter than air, and leaked ammonia rises up.
     
  • Low energy density. Energy density of ammonia is approximately similar to methanol or dimethyl ether – less than half of energy density of popular diesel oil, gasoline or aviation fuel. That means ammonia is not good fuel for aviation, if we compare to hydrocarbons, but on the other hand ammonia is much better than an electrochemical battery.
Transuranic heavy elements may not be used where there is life.
– Sapphire & Steel intro

jagdish
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Re: Carbon neutral synthetic fuels

Post by jagdish » Jan 31, 2019 7:26 pm

A lot of carbon has been mined and most of it has landed in oceans. We could recycle it, including via the biomass.
The life cycle of earth can tolerate a lot of variation in carbon quantities. Some poisons like sulphur and suspended particles are more dangerous for our health and need to be controlled.
The synthetic fuel cycle should preferably be methanol/ethanol and high efficiency fuel cells which do not introduce harmful products in the atmosphere.
Poisons like ammonia should be kept down to minimum required.

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nipo
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Re: Carbon neutral synthetic fuels

Post by nipo » Feb 10, 2019 6:56 pm

I think that all hydrocarbon fuels could be left for aviation only. All other traffic could proceed to increased use of electricity (i.e. railways), battery powered cars, or completely carbonless fuels, such as ammonia. Many are enthusiastic about pressurized hydrogen (not me) but certainly that is also one alternative.

Methanol and DME would be excellent synthetic fuels, but the question about carbon seems to be very difficult.

There seems to be at least one useful combustion process for an internal combustion engine that could use ammonia as fuel.
• Lee, Dongeun et al: Development of new combustion strategy for internal combustion engine fueled by pure ammonia (PDF) 2017-11-01. Seoul National University, Department of Mechanical Engineering.

I got an idea about another combustion process. That would include very high compression ratio which is absolutely required in case of ammonia fuel, direct fuel injection into cylinder, stratified charge, and microwave ignition. In this case microwave ignition would be the key to ignite ammonia-air fuel charge quickly. I hope that compression ratio could be as low as 20:1.
Transuranic heavy elements may not be used where there is life.
– Sapphire & Steel intro

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