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Making Jet Fuel From Seawater While at Sea

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Re: Making Jet Fuel From Seawater While at Sea

#51

Post by regularfry »

Roritharr wrote: post #39
zmmz wrote: post #37

Earlier quoted context omitted.

It's not that simple: CO2 in atmosphere -> CO2 in water -> Ocean acidification[1] -> Change in ocean ecosystem The oceans absorb OC2 from the atmosphere, which you could argue is good, but it is not without consequences. Putting CO2 in the water moves the problem from having it in the atmosphere elsewhere, but it's still a problem. In some ways then, this can be seen as a good thing, because it is undoing the effects…

I'm not for putting more carbon into the oceans... just against taking the currently stored carbon out.

There is already too much. Any we can take out is a good thing.

Re: Making Jet Fuel From Seawater While at Sea

#52

Post by xefer »

regularfry wrote: post #51
Roritharr wrote: post #39

Earlier quoted context omitted.

I'm not for putting more carbon into the oceans... just against taking the currently stored carbon out.

There is already too much. Any we can take out is a good thing.

But it's taking carbon out of the ocean and releasing it into the atmosphere. The issue becomes, how long does it take for the released atmospheric CO2 to be reabeorbed back into he ocean? Does it do more harm in the atmosphere or in the ocean?

Re: Making Jet Fuel From Seawater While at Sea

#53

Post by danielharan »

ta12121 wrote: post #42
sien wrote: post #27

Earlier quoted context omitted.

If they can hit $3 / gallon why does it matter? Tesla's cars are wildly price inefficient because they cost $100K. For 10K you can get a decent car that has 4 times the range. http://en.wikipedia.org/wiki/Tesla_Roadster How many gallons of fuel can you get for 90K? They are nice toys for rich people. Perhaps there is a market for that. Good luck to them. But for mass transit unless you can get the price of the batter…

$3 a gallon is what the fuel costs today when it comes straight out of the ground. Claiming to be able to build and run a nuclear reactor and then synthesize the fuel through multiple energy inefficient steps all for the same price is a pipe dream.

It's not competing against the price straight out of the ground; it's competing against fuel that's been refined and delivered to a moving ship somewhere potentially very far away. Instead of $3 a gallon, it could be up to 10X more.

Re: Making Jet Fuel From Seawater While at Sea

#54

Post by stcredzero »

dalke wrote: post #33
sien wrote: post #16

This is a good reason why Tesla cars are folly. This is why electric vehicles won't work. I'll copy in most of a comment I made a few days back. Let's say tomorrow some grad student gets fusion going at a very low price. The best way to use this to power cars would be to use it to create a fuel with a high energy density. If you had 'free energy' you'd extract C02 from the atmosphere and turn it into a hydrocarbon. F…

"Let's say tomorrow some grad student gets fusion going at a very low price. The best way to use this to power cars would be to use it to create a fuel with a high energy density." That is incorrect. If the fusion source is compact, and can produce a lot of instantaneous electrical power, and is quick to throttle up and down, then a "Back to the Future"-style Mr. Fusion would be the best way to power cars. Energy den…

> That is incorrect. If the fusion source is compact, and can produce a lot of instantaneous electrical power, and is quick to throttle up and down, then a "Back to the Future"-style Mr. Fusion would be the best way to power cars.

There's also safety to consider.

Re: Making Jet Fuel From Seawater While at Sea

#55

Post by antidoh »

danielharan wrote: post #53
ta12121 wrote: post #42

Earlier quoted context omitted.

$3 a gallon is what the fuel costs today when it comes straight out of the ground. Claiming to be able to build and run a nuclear reactor and then synthesize the fuel through multiple energy inefficient steps all for the same price is a pipe dream.

It's not competing against the price straight out of the ground; it's competing against fuel that's been refined and delivered to a moving ship somewhere potentially very far away. Instead of $3 a gallon, it could be up to 10X more.

And, dollar cost of the fuel is not the only cost of maintaining a "long supply tail." There's also the dollar cost of all the ships and sailors on that tail, and there's the logistical opportunity costs: we have to protect that tail with military resources that might otherwise have gone to more directly military purposes, and the head of the tail (the military activity at the front) is held back and slowed down by a "heavier" supply tail.

This doesn't eliminate the tail (we still have to deliver ammunition, lubricating oil, food etc. to the fleet) and it doesn't eliminate replenishment at sea (we still have to get that stuff from supply vehicles to ships), but it does lighten the supply load and create more military options.

Re: Making Jet Fuel From Seawater While at Sea

#56

Post by pigboy »

sien wrote: post #16

This is a good reason why Tesla cars are folly. This is why electric vehicles won't work. I'll copy in most of a comment I made a few days back. Let's say tomorrow some grad student gets fusion going at a very low price. The best way to use this to power cars would be to use it to create a fuel with a high energy density. If you had 'free energy' you'd extract C02 from the atmosphere and turn it into a hydrocarbon. F…

Energy density is a critical issue for aircraft because lift/drag ratios are capped at around 15 to 30. For every 15-30 N of fuel weight, you must supply at least 1 N of additional thrust (which translates to power, once you multiply by speed).

Cars, on the other hand, experience a combination of aerodynamic and powertrain drag and rolling resistance, of which only (mostly?) the rolling resistance depends on mass. The typical coefficient of rolling resistance is about 10x better than the typical L/D ratio for aircraft (if I believe Wikipedia). Hence, road vehicles are 10x less sensitive to energy density than aircraft.

So a statement that electric vehicles won't work is nonsense, without considering how sensitive the different vehicles are to fuel mass.

Re: Making Jet Fuel From Seawater While at Sea

#58

Post by [deleted] »

ta12121 wrote: post #45
iwwr wrote: post #31

Earlier quoted context omitted.

It's energy inefficient, but you're thinking in terms of energy scarcity we have today. What if we had 10x more electric energy capacity (most likely due to nuclear resurgence)?

Energy scarcity is a fundamental property of technology and economics. Aside from a few countries like France, nuclear power serves a fraction of our electricity needs, and electricity is a fraction of our total energy needs. Where are all these nuclear power plants going to come from? The technology described in the article is a way to transform energy. Not to produce it.

[deleted]

Re: Making Jet Fuel From Seawater While at Sea

#59

Post by sophacles »

stcredzero wrote: post #54
dalke wrote: post #33

Earlier quoted context omitted.

"Let's say tomorrow some grad student gets fusion going at a very low price. The best way to use this to power cars would be to use it to create a fuel with a high energy density." That is incorrect. If the fusion source is compact, and can produce a lot of instantaneous electrical power, and is quick to throttle up and down, then a "Back to the Future"-style Mr. Fusion would be the best way to power cars. Energy den…

> That is incorrect. If the fusion source is compact, and can produce a lot of instantaneous electrical power, and is quick to throttle up and down, then a "Back to the Future"-style Mr. Fusion would be the best way to power cars. There's also safety to consider.

On top of that, reliability. To have a large plant with a high mechanical complexity which can justify dedicated maintenance workers to help manage complexity and the results of part wear etc is likely able to achieve the same or higher reliability than a backyard unit, in TCO terms anyway.

Re: Making Jet Fuel From Seawater While at Sea

#60

Post by DennisP »

xefer wrote: post #52
regularfry wrote: post #51

Earlier quoted context omitted.

There is already too much. Any we can take out is a good thing.

But it's taking carbon out of the ocean and releasing it into the atmosphere. The issue becomes, how long does it take for the released atmospheric CO2 to be reabeorbed back into he ocean? Does it do more harm in the atmosphere or in the ocean?

Right now we're taking carbon out of the ground and putting it in the atmosphere.

The ocean presently has a lot of extra carbon, which it absorbed from the atmosphere. So this is an indirect way of taking carbon out of the atmosphere and then putting it back...a closed loop. If we did this for all our hydrocarbon fuel we'd be carbon-neutral.

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