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[10ebbor10]

Anyway, just as a note you don't get twice the energy per unit of carbon pumped into the athmosphere.

Point, though it would allow for much higher solar energy utilization because we would have a more easily stored and widespread form of solar energy than through electricity/water.

Do we? I'm quite sure the efficiency is lower than current storage methods. (Fossil fuel generators only have a 40% efficiency, after all.) Meanwhile, the losses for pumped storage and electricity storage are much lower. A pumped storage facility has an efficiency of 70-80%, even with an addition 5% grid and 5% misc losses, is still 50% more efficient.

Meanwhile the synfuel process isn't exactly efficient either.

The only advantage is that you don't need additional infrastructure.

[ChairmanPoo]

You know that biofuel production has been disastrous in Iberoamerica, right? As it turns out, dedicating large chunks of the harvest to fuel production drives food prices up quite a bit.

[10ebbor10]

Not all synfuel is biofuel. While a large part of it is, there's also synfuel drawn from coal, gas and heavy oils, or in this case, from Co² directly.

[Descan]

You know that you're the first person to even bring up biofuels, and that everyone has been discussing other methods of artificial fuel, right? As it turns out, we have some methods of creating hydrocarbons, it just requires energy and CO2 and water (some of them also require catalysts), and atmospheric CO2 at this point doesn't quite cut it for an industrial-scale process.

[i2amroy]

The only advantage is that you don't need additional infrastructure.

And that it can be implemented anywhere. There are very sizable chunks of the world that don't have near the elevation required for a pumped water facility, nor have the geographical features required for a compressed gas facility. While it will probably never come close to the efficiency for those in areas where they are supported, the fact that it can be easily implemented anywhere allows it to easily be used in areas that support neither one.

[Sheb]

Also, while water storage is great on paper, it doesn't suit every application. You can't have a dam in your trunk to provide power for your car.

[10ebbor10]

On a side note, we appear to have 2 different things going on here.

1) People proposing the Synfuel thing as a replacement of fossil fuels.
 
It's a solution that makes a little bit more sense, but electric cars still have the thing beaten on energy efficiency. The main advantage of synfuel is their energy density, which is still a major problem for electric appliances.

2) People proposing the Synfuel as a solution to intermittent supple of renewable energy.

This is, to say it bluntly, quite stupid. As far as I could find, the Synfuel process using electricity* has an efficiency of about 15%-20%, and isn't going to improve dramatically. Converting this synfuel back to electricity, you're facing with another 60% losses. This means that you only recuperate 8% of the energy you store.

I mean, you could install a high voltage line, a battery power unit or whatever else you want for power and it will be both cheaper and more efficient.

*Also assumes that you don't have to invest any energy to get your 100% pure Co² feedstock.

[Sheb]

Electric cars may be energy-efficient, but you have to factor in the huge energy cost of manufacturing those batteries.

[10ebbor10]

Not enough to make a difference.

[Helgoland]

Also the resources needed to convert all current cars to/replace them with electrical ones. And the new infrastructure that would be needed. Etc etc

[Sheb]

Yeah, that's the attraction on synfuel. Sure, it's not the best solution, outside of a few applications (Basically when you really need high energy density. Airplane fuel for example), but it's drop in: you don't need to build the whole infrastructure and change the whole car fleet etc etc.

[10ebbor10]

But what's the point of an electricity based drop-in solution, when that electricity is generated using fossil fuels. Because really, renewables aren't there yet.

[Helgoland]

Fossils-to-electricity-to-synfuel is dumb, yeah. But so is fossils-to-electricity-as-fuel. And synfuel plants don't have to operate continuously - they might be used to take care of energy peaks, which are a large problem with renewables. We'll ultimately have to take all our energy from fission and renewables, which means that future mobility will be electricity-based one way or another: Synfuel is just the more elegant solution, because it causes fewer problems during transition.

[10ebbor10]

Fossils-to-electricity-to-synfuel is dumb, yeah. But so is fossils-to-electricity-as-fuel. And synfuel plants don't have to operate continuously - they might be used to take care of energy peaks, which are a large problem with renewables. We'll ultimately have to take all our energy from fission and renewables, which means that future mobility will be electricity-based one way or another: Synfuel is just the more elegant solution, because it causes fewer problems during transition.

Fossil to electricity as fuel isn't that bad. Large generators have the advantage of scale resulting in higher efficiency. IIRC, 40% for natural gas, +20% if you're using cogeneration for heating as opposed to the 20% of most cars. With electric efficiency at 60%-80%, that's a decent gain. 

And it's probably going to be much more fission than renewables, if you plan to go through with that. As an example, if we were to transfer all of the UK's energy useage to Electric using perfect conversion, it would need a 250 GW of generation capability. Now, conversion isn't perfect, so that power usage is going through the roof.

Additionally, a synfuel plant requires a nearby fossil fuel plant for it's Co² (atmospheric filtering will crash the already low efficiency). I mean, it's not an elegant solution if it relies on the infrastructure you're trying to replace.

[Sheb]

Not all synfuel require electricity as an input. Biodiesel from algae is one such example.