Energy From Thorium Discussion Forum

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PostPosted: Jan 11, 2014 8:52 pm 
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These things are plausible but are going to require significant development.

The mechanical strength of membranes issue with the electrolysis cells alone can cause issues during cycle of the systems on and off for maintenance.

I still think relatively low pressure electrolysis followed by either methanol synthesis (and then methanol to gasoline) or direct F-T/SMDS of syngas is the better option.

Then you can forget the fuel cells and just run conventional diesel engines (and in the longer term those combined cycle Turbosteamer things various German firms are working on)


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PostPosted: Jan 12, 2014 4:16 am 
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Liquid fuel are certainly more practical, especially if synthetic gasoline or diesel. Then you'd use the same delivery trucks and tankers. There's a pretty heavy price to pay in efficiency however. Pulling carbon from the air or sea, making methanol, then MTG, likely you're wasting more than 30% of the energy to get there.

Direct methanol engines are supposed to be much more efficient than gasoline engines, peak efficiency of 50% is claimed, so that's something to consider, especially with ethanol compatible cars becoming widespread.


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PostPosted: Jan 12, 2014 10:08 am 
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Methanol is illegal in the US:
http://www.openfuelstandard.org/2012/08 ... t-our.html

Quote:
According to the EPA (FRL-9620-5, published January 20, 2012), “Section 211(f)(1) of the Clean Air Act makes it unlawful for any manufacturer of any fuel or fuel additive to introduce into commerce, or to increase the concentration in use of, any fuel or fuel additive . . . which is not substantially similar to any fuel or fuel additive utilized in . . . 1975. . . . The current ‘substantially similar’ interpretive rule for unleaded gasoline allows oxygen content up to 2.7 weight [sic] for certain ethers and alcohols.”


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PostPosted: Jan 12, 2014 10:34 am 
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Methanol may allow for efficient engines but it has a rather low energy density so you will need larger fuel tanks both for storage and in the final vehicle.

I am not sure it can really match up against a modern turbodiesel, especially if it has a rankine heat recovery cycle on the bottom.


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PostPosted: Jan 13, 2014 6:15 am 
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Dehydrated methanol or di-methyl ether can be compressed to liquid at ordinary temperatures. It can be used in spark ignited or diesel engines or gas turbines. Its energy density is better than methanol but short of hydrocarbons. It could be the right synthetic fuel choice for conversion from coal, gas or biomass. It beats high pressure gas for vehicles or fuel cells.


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PostPosted: Jan 13, 2014 11:32 am 
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Does anybody know how much energy it takes to go from methanol to synthetic gasoline or DME? I would guess that methanol would be a lot more cost-effective. I think most people would trade range for cost. Since methanol cars would be flex fuel, you could use gasoline if you wanted to go on a long trip.


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PostPosted: Jan 13, 2014 12:00 pm 
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Well this handy brochure seems to indicate that it is not that difficult. The process happens to be slightly exothermic (1.74MJ/kg of Methanol injected)

Additionally methanol can be converted into Olefins via a similar process.

Although if we are making syngas it might be better to max wax via F-T so we can crack it into valuable fractions using a variant of the SMDS process.


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PostPosted: Jan 13, 2014 12:48 pm 
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E Ireland wrote:
Well this handy brochure seems to indicate that it is not that difficult. The process happens to be slightly exothermic (1.74MJ/kg of Methanol injected)

Additionally methanol can be converted into Olefins via a similar process.

Although if we are making syngas it might be better to max wax via F-T so we can crack it into valuable fractions using a variant of the SMDS process.


That reference is for coal conversion into methanol then to gasoline products.

Not using coal means more energy expenditure to get the carbon from the air or sea.

Also the ref mentioned 15-20% loss for conversion of the first step. But it didn't mention the efficiency of the second step that actually converts to gasoline products over the zeolite catalyst. What's the energy loss there?

What's the efficiency of making diesel like products (higher alkanes than gasoline) from methanol? Surely its worse than making gasoline?


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PostPosted: Jan 13, 2014 2:16 pm 
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jagdish wrote:
Dehydrated methanol or di-methyl ether can be compressed to liquid at ordinary temperatures. It can be used in spark ignited or diesel engines or gas turbines. Its energy density is better than methanol but short of hydrocarbons. It could be the right synthetic fuel choice for conversion from coal, gas or biomass. It beats high pressure gas for vehicles or fuel cells.

With an antiknock index of around 20 it would be a terrible fuel for a spark ignited engine. However, as a small molecule with a low carbon content and no carbon-carbon bonds it might be much better than diesel (fossil or synthetic) for compression ignition applications, with far less particulate production and likely less toxic gas emissions as well.


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PostPosted: Jan 13, 2014 2:45 pm 
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Titanium48 wrote:
jagdish wrote:
Dehydrated methanol or di-methyl ether can be compressed to liquid at ordinary temperatures. It can be used in spark ignited or diesel engines or gas turbines. Its energy density is better than methanol but short of hydrocarbons. It could be the right synthetic fuel choice for conversion from coal, gas or biomass. It beats high pressure gas for vehicles or fuel cells.

With an antiknock index of around 20 it would be a terrible fuel for a spark ignited engine. However, as a small molecule with a low carbon content and no carbon-carbon bonds it might be much better than diesel (fossil or synthetic) for compression ignition applications, with far less particulate production and likely less toxic gas emissions as well.


I think that's the idea with methanol engines, yes. A high compression ratio is achievable. Here's a presentation on some possibilities with methanol fuel from MIT.

http://academic.sun.ac.za/microbiology/ ... edrone.pdf

They are claiming a 50% increase in efficiency over a spark ignited gasoline engine. That's probably peak efficiency though (these are the advocates talking). The actual MPG improvement will probably be a fair bit lower.

Still, it's clear that the energy density penalty is offset by increased engine efficiency. So you'd get as far as gasoline for a given tank size.


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PostPosted: Jan 13, 2014 4:42 pm 
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Cyril R wrote:
That reference is for coal conversion into methanol then to gasoline products.

Not using coal means more energy expenditure to get the carbon from the air or sea.

Also the ref mentioned 15-20% loss for conversion of the first step. But it didn't mention the efficiency of the second step that actually converts to gasoline products over the zeolite catalyst. What's the energy loss there?

What's the efficiency of making diesel like products (higher alkanes than gasoline) from methanol? Surely its worse than making gasoline?


That 15-20% is the fraction of the overall heat of reaction released in that step. (So 15% of the 1.74MJ)
Not 15-20% of the energy of the fuel energy of the injected methanol.

While the reference does couch the methanol process as part of a chain from Coal it only deals with the steps after methanol product is obtained so I think that context is largely irrelevant.
You don't require any additional carbon to be obtained than you would with the methanol option, it is primarily about disposing of the unneccessary oxygen atoms that weigh down the product without contributing significant amounts of energy.

Diesel from Methanol is indeed problematic, which is why it would probably be better to direct your artificial syngas directly to Fischer-Tropsch synthesis instead of Methanol synthesis.
You could either attempt to product product diesel directly or follow Shell's example and produce wax that can then be cracked into any desired products using standard refinery equipment.


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PostPosted: Jan 13, 2014 4:46 pm 
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According to MIT, the methanol compression engine is more efficient than a diesel compression engine, by around 25%. So I think that would allow the best of both worlds, an efficiently synthesizeable fuel (methanol) and a high efficiency diesel engine (except it runs on methanol).

Near term I understand that syngasoline from methanol is attractive, its a drop-in fuel replacement, but long term, I think the efficiency advantage and reduction in refining costs may make methanol more attractive as a fuel.


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PostPosted: Jan 13, 2014 5:11 pm 
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I am rather skeptical of Methanol or DME as a diesel fuel.
Ther are the fuel density problems, the fuel engineering problems and the environmental issues.

DME and similar ethers are banned as gasoline additives in significant portions of the world as they are water miscible and thus difficult to clean up after leaks.
Immiscible liquids can't infiltrate the water table in the same way.


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PostPosted: Jan 13, 2014 5:26 pm 
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E Ireland wrote:
I am rather skeptical of Methanol or DME as a diesel fuel.
Ther are the fuel density problems, the fuel engineering problems and the environmental issues.

DME and similar ethers are banned as gasoline additives in significant portions of the world as they are water miscible and thus difficult to clean up after leaks.
Immiscible liquids can't infiltrate the water table in the same way.


Methanol isn't banned. I've got some in a flimsy plastic bottle. Enough to kill me if I were to drink it all. I feel very safe I assure you.

Immiscible liquids can't infiltrate, but they have their own problems. In one of my safety analysis for a storage depot we found gasoline had a big fire risk because it spills on the water in the harbor making a giant evaporative combustible area. It could set the entire harbor on fire. Ethanol was also stored there, it had a bigger aquatic risk but interestingly much smaller fire risks due to the diffusion into water. Immiscible liquids tend to have higher water birds risks as they swim and drink the surface water immiscible layer. Its a tough call which is better. From my experience diesel is one of the safest in both fire and ecological risks, so if we can find an efficient way to synthesize diesel then that is very attractive.


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PostPosted: Jan 13, 2014 7:10 pm 
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Dimethyl ether boils at -24°C. It would likely be handled just like propane in above-ground storage tanks, and any leaks would vaporize immediately except in very cold weather (in which case the ground would be frozen and impermeable). It won't generate the same water contamination issues as methyl tert-butyl ether. There is still an explosion risk in the immediate vicinity of a large leak, but the only pollution risk from a leak is temporarily reduced air quality.


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