Researchers turn seawater into synthetic fuel

[jean.caissepas]

American researchers have successfully developed a process for recovering carbon dioxide (CO2) and hydrogen from seawater, which will then be converted into a liquid fuel that can be used directly.

Scientists at the Naval Research Laboratory (NRL) demonstrated the viability of this concept to the end by managing to fly a reduced plane model with synthetic kerosene produced precisely from seawater.

The energy balance is not fabulous, but for storing intermittent energies or obtaining bio-fuel ...

Link : http://www.enerzine.com/10/17155+des-chercheurs-changent-leau-de-mer-en-carburant-de-synthese+.html

[chatelot16]

nothing new

GTL is the new name for the fischer tropsh synthesis used in Germany to make synthetic fuel

CO and hydrogen are needed

making hydrogen by electrolyzing water is not new either: it is enough to have another source of energy to power


this system could be used to make liquid fuel when there is a renewable energy by exceeding: for example the sun in the countries which do not need heating

but I see it simpler: to concentrate CO2 there is better than electrolysis: trees or algae: it makes carbon

and to make liquid fuel, the first step is the gasifier

the efficiency of the gasifier can be considerably improved if it is heated: it itself becomes a solar collector: the result contains both energy from carbon and solar thermal energy
C + H20 = C0 + H2

then GTL or fischer tropsh makes oil

[Christophe]

+1 another false info ... to make some dream ...

Understood that the navy wanted to build nuclear factory boats ... proof that the process is very energy intensive! estimated cost price $ 100 to $ 200 per barrel !!

The exploitation of ETM and microalgae are "infinitely" more interesting! cost of microalgae barrel: $ 40 ...

See https://www.econologie.com/forums/energie-th ... t4853.html et https://www.econologie.com/forums/microalgue ... 10514.html

[Gaston]

There is no miracle...

If 1 liter of this synthetic kerosene can provide about 10 kWh when burning, it takes at least 10 kWh to synthesize this liter.

In practice, with the yields of electrolysis and the Fischer-Tropsch reaction, it is probably necessary to count rather 20 to 50 kWh per liter ...

Hence the order of magnitude of the estimated cost of $ 1 per liter.

[gildas]

With seawater you have to get rid of the salt.

You just have to bubble CO2 in a Gillier-Pantone bubbler ...

[chatelot16]

seawater is just one more complication, electrolysing salt water makes chlorine that eats everything ... you have to desalt first

even when we electrolyzed fresh water supplied by dams in the Nordic countries, we distilled first to get rid of limestone ...

I come back to my solar gasifier: it is the only thermal means of decomposing water to make hydrogen: therefore to directly benefit from a heat from a solar oven without going through a thermal machine

2H2O = 02 + 2H2
but without carbon it never works: it decomposes at high temperature and recomposes too quickly when cooling

thanks to the presence of carbon oxygen is trapped to make CO: that makes a fuel generator half biomass half solar thermal

anyway the water must be introduced in the form of steam, so you can boil sea water, there will be no salt in the steam

[Did67]

Last night at the France 2 news, there was talk of carbonates, contained in the water, which it was a question of "undoing" and "rebuilding" in hydrocarbons.

It is indeed the navy. The cost does not count, no more than the overall energy balance, which must still to stay positive, if not, I don't see the point.

But the fact that it is a gas plant as complex as a nuclear reactor should not be a problem for them.

There was still a question of speculation with production costs of 1 euros to 1,20 euros per liter "once large-scale installations ...".

And once again, the media rush into the myth of making hydrocarbons from water [variant of the "water engine"]

[chatelot16]

positive outcome?

no: it is a means of transforming an energy of indifferent origin, nuclear or solar kind into liquid fuel

seawater supplies hydrogen and carbon but without supplying energy

extracting CO2 from the air or water costs energy because it is too diluted, and once concentrated it still takes energy to return to a CO or C fuel stage

it is a shame not to use photosynthesis which works by itself by directly using the CO2 of the air and the sun without having to concentrate it

if it is necessary to make faster than the terrestrial vegetation there is algae

finally I see an interest coming from the navy gas plant: making fuel independently on a nuclear aircraft carrier, to power planes: it will work without question of profitability

alas it will be difficult to have precise information to use part of this process at another scale

[Gaston]

The cost does not count, no more than the overall energy balance, which must still to stay positive, if not, I don't see the point.

The overall energy balance is of course negative, this system must be seen as a means of storing energy (such as a battery, compressed air, water that is pumped up, ...): the yield is never 100%.

From the storage point of view, hydrocarbons are indeed very interesting: high mass and volume capacity, easy storage, good conservation, ...

Unless you have a (very) abundant and (almost) free source of energy, it is a technique to be reserved for difficult cases of energy supply, such as aviation.

In the case of the Navy, we do not know how to fly planes using the heat or electricity produced by an on-board nuclear reactor. On the other hand, if we know how to produce aircraft fuel on site, we gain in logistics and security of supply, and we don't worry too much about whether it takes 20, 50 or 100 kWh to produce 1 liter of kerosene ...

[chatelot16]

if this means of making liquid fuel could be done on a very small scale it would be good to use electricity in rab of photovoltaic panels on an isolated site

when you size correctly to be autonomous in winters, there is far too much in summer and you don't know what to do with it ... if a simple thing like an electrolyser made liquid fuel it would be good

alas electrolysis is only a first step to make hydrogen: the next step to make liquid fuel is a gas plant currently impossible to miniaturize

it will already be a great feat to do it on a nuclear aircraft carrier!