Forget drilling into the ocean floor to tap into ever-decreasing supplies of oil, because there could soon be a new fuel source beneath the waves – seaweed. A technique has been developed to convert sugars in seaweed into a fuel that can be used to power cars. Biofuels are currently produced from crops such as corn and sugar cane, but these sources are also in demand for use as food, and their production requires large amounts of land, fresh water and fertiliser. Seaweed requires none of these and has the advantage of not containing lignin, a strong strand of sugars that stiffens plant stalks but is difficult to turn into biofuel. Researchers at Bio Architecture Lab in California have been able to produce bioethanol from kombu, an edible brown seaweed. Bioethanol can be blended with petrol and used in engines with little or no modification. Brown seaweed has high sugar content and also grows more quickly than the red or green species. The only potential stumbling block is growing enough of the stuff. Several thousand tonnes are farmed annually for food, but if it is going to be used widely as a fuel, billions of tonnes would be required. But Bio Architecture Lab is still forging ahead, launching a seaweed biofuel pilot project in 2013. It hopes to commercialize seaweed-sourced fuels within three to four years.