The researchers showed that solar methanol islands could produce enough fuel in the long term to make all CO2 emitted from transportation sources neutral. In the oceans, hydrogen will to be produced from solar energy along with water. Then it will be converted into methanol on site using CO2 that is extracted from the seawater.
This idea is based on solar islands, namely floating platforms that have photovoltaic systems. Nevertheless, as solar power cannot be stored and transported from there, a solar power plant on the is not sensible.
For this reason, the researchers' idea is that the raw materials could be gathered directly from the ocean or produced there.
Currently, there are large-scale power-to-gas plants that convert hydrogen and CO2 into fuel. This leads to the question, why go to sea with it? According to the researchers, the answers would be because the space needed for a global supply of fuel would be enormous.
As Andreas Borgschulte of Empa's Advanced Analytical Technologies lab, explains an area of about 170,000 km2 would be necessary, This can be achieved by solar power systems at sea.
In land plants, the CO2 extracted from the atmosphere is mainly used to produce methane, which would also be done on the solar islands. However, the researchers decided to produce a liquid fuel, as they believe it would be easier to transport.
What is more, methanol can also be used as means to manufacture other chemical products, like precursors for polymer production. This greatly enhances the possibilities for its use.
This kind of project nonetheless would cost about 90 million US dollars. It would include nearly 70 photovoltaic islands, with a diameter of about 100 m2, as well as a vessel with the electrolysis and synthesis plants. This would lead to an area of about 550,000 m2, however the researchers mentioned that a single cluster is not enough to achieve a zero balance of CO2.
In fact, 170,000 such islands would be needed to recycle as much CO2 as is currently emitted.