Seawater covers around 70 per cent of the Earth’s surface and accounts for 97 per cent of the planet’s water. Although a great source of food and means of travel, in some ways this ubiquitous resource is under-used, especially in relation to its energy potential.
Of course renewable wave energy is attracting lots of interest at the moment. But a few weeks ago, a story caught my eye about a team at the U.S. Naval Research Laboratory (NRL), who have been looking at seawater as a means to power their warships and planes.
If they succeed it would provide an endless source of energy and remove one of the great limiters to long ocean journeys – the need to re-fuel ships, and even carrier aircraft. The potential of this development for civilian use is also significant.
The NRL’s scientist are developing a process to extract carbon dioxide (CO2) and produce hydrogen gas (H2) from seawater, subsequently catalytically converting the CO2 and H2 into jet fuel by a gas-to-liquids process.
The process uses a catalyst that is similar to those used for Fischer-Tropsch reduction and hydrogenation of carbon monoxide. It modifies the surface composition of iron catalysts in fixed-bed reactors and NRL believe it has successfully improved CO2 conversion efficiencies up to 60 percent.
NRL have also used the technology to look at its potential to power aircraft. Earlier this year, they successfully demonstrated a novel liquid hydrocarbon fuel to power a model aircraft’s unmodified two-stroke internal combustion engine. The test was used to provide proof-of-concept for their process.
The predicted cost of jet fuel using these technologies is in the range of $3-$6 per gallon, and with sufficient funding and partnerships, they believe this approach could be commercially viable within the next seven to ten years.
Take a look at NRL’s video demonstrating the seawater powered flight of their model aircraft.