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A US Naval Research Laboratory (NRL) team has turned seawater into a hydrocarbon fuel, and used it to power a radio-controlled aircraft with an unmodified internal combustion engine. According to Dr Heather Willauer, the team’s leader, the fuel could eventually be used to power the Navy’s fleet of ships, allowing them to stay at sea longer and avoid travelling to dangerous refuelling regions.
The process takes the CO2 and hydrogen in seawater and recombines it over a catalyst, similar to those used for Fischer–Tropsch reduction and the hydrogenation of carbon monoxide, to create the liquid fuel. Although initial production costs are expected to be high (between $3 and $6 per gallon), its longterm potential for the US Navy is huge, says Willauer: “The potential payoff is the ability to produce fuel at sea, reducing the logistics tail on fuel delivery with no environmental burden and increasing the Navy’s energy security and independence.
But the scope extends beyond the Navy’s fuel security. Depending on the base metal used in the catalyst (iron, cobalt, nickel or copper, for example), seawater could be turned into methanol and natural gas, which could be used for green energy generation. “Another potential benefit”, says Will Dawson, Head of Energy at Forum for the Future, “would seem to be a slower rate of ocean acidification, which is killing habitats such as coral reefs”.
The logic runs that, by using a fuel made from already emitted carbon, we wouldn’t be increasing the ocean’s CO2 content further. The long-term outcome could be that the ocean’s increasing pH levels slow down, and even eventually stop.
However, the fuel has only just passed the proof of concept stage and the NRL believes it won’t be commercially viable for another decade. “It’s not necessarily going to be the one and only solution to alternative fuels”, says Willauer. “It’s just one solution that hopefully many people are going to use.”
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