Official US Navy Press Release:
http://www.navy.mil/submit/display.asp?story_id=80171
Take note: No mention of ending the US military dependence on fossil (hydrocarbon) fuels.
Facts and numbers according to the press release:
1. Seawater contains higher level of Carbon Dioxide "if" compared to air. It mentions 100 mg/L (Convert to percent - 0.01%)
2. Dissolved Carbon Dioxide gas and Hydrogen gas in seawater is extracted using electrolytic cation exchange (90% efficiency).
3. Both gases are converted to liquid form using gas to liquid synthesis with iron as catalyst (60% efficiency).
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Do the math and compute how many gallons of seawater needed to produce a gallon of the liquid fuel fraction (and this is still a fraction). Pumping alone the seawater raw material will likely consume the predicted 6 USD cost of this fuel. Processing that same volume of seawater is another matter and will need a ton of energy.
In fairness, this technology is novel and innovative. However, it boils down to cost and efficiency. It is much cheaper to pump out oil in the desert or buy crude in the Middle East.
However, this could be put to good use (at a cost disadvantage) during fuelling jets in carrier groups wherein there is surplus supply of energy due to the ship's nuclear reactor and the ship is literally floating in seawater instead of supply ships pumping jet-fuel in remote locations.