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Making Jet Fuel From Seawater While at Sea

nrl.navy.mil

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Re: Making Jet Fuel From Seawater While at Sea

#41

Post by wisty »

sien wrote: post #27
ta12121 wrote: post #20

Earlier quoted context omitted.

No. Electrolysing water to make H2 and extracting CO2 from the environment, and then synthesizing hydrocarbons from them, is extremely energy inefficient. Sure, theoretically, it can be done, and maybe one day it could even be done efficiently. But Tesla is making battery-electric cars that work today . The military does not care about efficiency because they have nuclear reactors on their ships and their goal is to…

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…

Telsa cars are expensive for the same reason Ferraris are - they target people who want bling.

A mass-produced commuter could be much cheaper, but there's a huge risk. Tesla aims to reduce the risk by validating the market, solving technical problems, creating infrastructure (recharge stations) and solving social problems (convincing people that range doesn't always matter, and educating them on the strengths and weaknesses of electric cars).

A low total-cost (including fuel and maintenance) electric car can probably be produced, but it's not the Tesla's top model.

Re: Making Jet Fuel From Seawater While at Sea

#42

Post by ta12121 »

sien wrote: post #27
ta12121 wrote: post #20

Earlier quoted context omitted.

No. Electrolysing water to make H2 and extracting CO2 from the environment, and then synthesizing hydrocarbons from them, is extremely energy inefficient. Sure, theoretically, it can be done, and maybe one day it could even be done efficiently. But Tesla is making battery-electric cars that work today . The military does not care about efficiency because they have nuclear reactors on their ships and their goal is to…

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.

Re: Making Jet Fuel From Seawater While at Sea

#43

Post by jrabone »

ChuckMcM wrote: post #24
jnw2 wrote: post #15

Earlier quoted context omitted.

http://en.wikipedia.org/wiki/USS_Gerald_R._Ford_(CVN-78) notes that ``Unfortunately the power limitations for the Nimitz class make the installation of the recently developed [Electromagnetic Aircraft Launch System] impossible.'', which seems to indicate that existing nuclear powered aircraft carriers don't always have large amounts of electricity to spare. However, more electricity will be available on future aircra…

If you look at the power requirements for the EMALs system you will see why a Nimitz class carrier can't power it. Not only is it a crapload of power, its needed all at once. The JP4 from Seawater project can run at much lower powers and for long periods of time.

And in fact, here is another illustration of just how hard it is to replace conventional energy storage systems with electricity. High pressure steam stores an enormous amount of energy. EMALs effectively uses 4 flywheels as rotational energy stores, suggesting battery / supercap technology just isn't viable. It does have an efficiency advantage over steam though.

Re: Making Jet Fuel From Seawater While at Sea

#44

Post by [deleted] »

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.

[deleted]

Re: Making Jet Fuel From Seawater While at Sea

#45

Post by ta12121 »

iwwr wrote: post #31
ta12121 wrote: post #20

Earlier quoted context omitted.

No. Electrolysing water to make H2 and extracting CO2 from the environment, and then synthesizing hydrocarbons from them, is extremely energy inefficient. Sure, theoretically, it can be done, and maybe one day it could even be done efficiently. But Tesla is making battery-electric cars that work today . The military does not care about efficiency because they have nuclear reactors on their ships and their goal is to…

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.

Re: Making Jet Fuel From Seawater While at Sea

#46

Post by jrabone »

confluence wrote: post #38
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…

You are wrong. Electric engines run at 92% efficiency. Car engines run at ~15%. So energy density need not reach equivalence. That physicist is wrong too (Nobel prizes don't mean you aren't wrong - it just means people listen to you more) - jet engines on planes require oxygen to work - hence capped at ~10 km altitude with massive drag causing ineffecient travel. 10 years till battery tech reaches complete parity for…

What? 10 years until battery technology has advanced to the point of parity?

Gasoline has an energy density of 132 MJ/US gal, or say 1500 MJ on a full small tank. Modern engines hit 30% thermal efficiency, but then there are drive train losses etc, so I'll give you the 15% as an absolute worst case, AND give you a 100% efficient electric motor / drive train. Therefore your car needs to provide 225 MJ of stored energy for parity.

The best commercially-available Li-ion battery has an energy density of around 245 Wh/kg, or ~ 880 kJ/kg. Therefore you need at least 255kg of conventional batteries for motive energy parity (ie. not counting heat/AC/light etc.). The equivalent in gasoline (0.77 kg/l), weighs 35 kg.

You are asking for nearly a ten-fold increase in usable energy density in battery technology in ten years, at price-parity with gasoline, and with the charging infrastructure to support it. I don't think it's going to happen - assuming lithium-air batteries ARE commercialised on that time scale, the cost of charging that kind of energy in reasonable time, safely, is going to be the real problem here. Every gas station is going to need its own nuclear power plant!

Re: Making Jet Fuel From Seawater While at Sea

#47

Post by 1rae »

FrojoS wrote: post #26

Once again, military research might lead the way. Note, if they invest into this, it's _not_ because of reduced price, increased efficiency or reduced greenhouse effects, but because of an _strategic_ advantage against "the enemy". Personally, I read about similar methods, for synthesizing carbon based fuels, many times before. Most of them were private founded but rather small scale. I can't judge if there was a sig…

I think Sasol (SA) has this Gas-To-Liquid fuel system working, and on a larger commercial scale http://www.sasol.com/sasol_internet/frontend/navigation.jsp?...

Re: Making Jet Fuel From Seawater While at Sea

#48

Post by confluence »

jrabone wrote: post #46
confluence wrote: post #38

Earlier quoted context omitted.

You are wrong. Electric engines run at 92% efficiency. Car engines run at ~15%. So energy density need not reach equivalence. That physicist is wrong too (Nobel prizes don't mean you aren't wrong - it just means people listen to you more) - jet engines on planes require oxygen to work - hence capped at ~10 km altitude with massive drag causing ineffecient travel. 10 years till battery tech reaches complete parity for…

What? 10 years until battery technology has advanced to the point of parity? Gasoline has an energy density of 132 MJ/US gal, or say 1500 MJ on a full small tank. Modern engines hit 30% thermal efficiency, but then there are drive train losses etc, so I'll give you the 15% as an absolute worst case, AND give you a 100% efficient electric motor / drive train. Therefore your car needs to provide 225 MJ of stored energy…

I'm assuming nuclear fusion is viable with the development of the ITER and DEMO plants in the South of France.

If they aren't viable - I'm calling time of death on the world.

Re: Making Jet Fuel From Seawater While at Sea

#49

Post by fpp »

jws wrote: post #3

Extract CO2 and H2 from seawater, react to form hydrocarbons of varying lengths, then refine. Presumably all powered by the nuclear reactors. initial studies predict that jet fuel from seawater would cost in the range of $3 to $6 per gallon to produce

A bit of history on the work of the NRL on modified Fischer-Tropsch processes / Hydrogenation:

From Wikipedia on Fischer-Tropsch: ( http://en.wikipedia.org/wiki/Fischer–Tropsch_process )

Carbon dioxide reuse

In 2009, chemists working for the U.S. Navy investigated a modified Fischer–Tropsch process for generating fuels. When hydrogen was combined with the carbon dioxide over a cobalt-based catalyst, the reaction produced mostly methane gas. However, the use of an iron-based catalyst reduced methane production to 30 per cent with the rest being predominantly short-chain, unsaturated hydrocarbons [27] The introduction of ceria to the catalyst's support, functioning as a reverse water gas shift catalyst, furthermore increased the yield of the reaction. [28]. The short chain hydrocarbons were successfully upgraded to liquid fuels over solid acid catalysts, such as zeolites.

[A patent application and a more in-detail research paper describing the process(es) is referenced there.]

Overall this looks very interesting as a military application (independence from other sources, logistics).

You will find more articles from 2009+ on this topic by searching for "Fischer-Tropsch seawater".

Re: Making Jet Fuel From Seawater While at Sea

#50

Post by Gravityloss »

ChuckMcM wrote: post #10
jws wrote: post #3

Extract CO2 and H2 from seawater, react to form hydrocarbons of varying lengths, then refine. Presumably all powered by the nuclear reactors. initial studies predict that jet fuel from seawater would cost in the range of $3 to $6 per gallon to produce

That is exactly why its such a big deal. Current jet fuel costs over $8/gal delivered. It costs so much because even if it comes out of the refinery at San Diego at $2/gal it has to be loaded into an oiler [1] and then driven out to sea where the carrier task group is. If you're on a nuclear powered aircraft carrier you have plenty of electricity so this is a pretty huge win. Of course an alternative way to make this…

We can look at it this way too: assume an oiler has maybe 10,000 t of oil and takes ten days to travel: 1E7 kg with energy density of 1E7 J/kg, in 1E6 seconds means an average power supplied by one oiler to be in the order of 100 megawatts. Or 10 kg/second. If that synfuel generation rate can be sustained, then the oiler is not needed.

The Nimitz class carriers have two 100 MW reactors: http://en.wikipedia.org/wiki/A4W_reactor

Of course, there's efficiencies, probably the oilers don't always go full speed, there's different distances etc etc...

If we assume 1% efficiency and one dedicated reactor, then we get 0.1 kg/second, 8 tons per day. You could load about two Hornets' internal fuel tanks with that.

In the sea you could probably also try other things than nuclear reactors, like farm algae and harvest it to produce biofuels (biofuel has already been tested in a B-52), or put solar or wind plants out in the ocean where there's space. No energy storage problems if the fuel is generated in situ.

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