Could artificial islands produce all of the world's fuel?David Wagman | June 07, 2019
Researchers say that solar methanol islands could produce enough fuel in the long term to make all CO2 emitted from transportation sources neutral worldwide.
Under the scheme, hydrogen (H2) would be produced from solar energy and ocean water, which then would be converted into methanol on site using CO2 extracted from the seawater.
The researchers, which represented from ETH Zurich, PSI and the Universities of Zurich, Bern and the Norwegian University of Science and Technology (NTNU) and Empa, analyzed a scenario that they presented in the journal Proceedings of the National Academy of Sciences.
The idea is based on floating platforms equipped with photovoltaic systems. Rather than trying to transport energy from the platforms to shore, the researchers proposed that liquid methanol (CH3OH) and gaseous methane (CH4) be produced from carbon dioxide and hydrogen. Their idea is that the raw materials could be obtained directly from the ocean or produced there.
Large-scale power-to-gas plants that convert hydrogen and CO2 already exist, but the space required for a worldwide supply of fuel would be enormous, the researchers said. They estimated that an area of around 170,000 km2 would be needed to produce the annual demand for global freight transport. This could best be achieved by solar power systems at sea, they said. Carbon dioxide also could be extracted from the air at sea, but an alternative would be to use the roughly 125 times higher CO2 concentration of seawater for the required gas.
The researchers said that in existing plants, CO2 extracted from the atmosphere is mostly used to produce methane, which also would be possible on the solar islands. The researchers decided, instead, to produce a liquid fuel because it is easier to transport. In addition, methanol can be used not only as a fuel, but also to manufacture other chemical products, such as precursors for polymer production.
Such a "methanol island" would cost around $90 million, the researchers estimated. This would consist of around 70 photovoltaic islands with a diameter of around 100 m2 and a ship with the electrolysis and synthesis plants. This would result in a total area of around 550,000 m2. They said that a total of 170,000 such islands would be needed to recycle as much CO2 as is currently emitted.