Nanostructured Filters in Shipping
Hardly anybody realizes that cargo ships rank among the biggest polluters of the planet. Approximately 55,000 cargo ships sail daily across oceans and are still powered by fuel that is much dirtier than diesel. This should be rectified by nanotechnology and nanostructured filters in the future.
According to the European Environment Agency, merchant ships discharge 204 times more sulfur than one billion cars on the roads worldwide. To make a more detailed idea ... Personal car having a mileage of 15,000 km a year produces a little over 100 grams of sulfur dioxide, whereas the largest cargo ships produce even more than 5,000 tons per year. Thus shipping contributes to global emissions of nitrogen oxides up to 30%, sulfur oxides a little less than 10% and the carbon dioxide of 4.5%. Of course, not only environmental activists but also the governments of the countries involved do not like this. Therefore, the International Maritime Organization adopted stricter emission limits, which, however, will take effect in 2020, but now it is necessary to work on alternatives for possible emission reductions.
In response to the reduction of sulfur emissions, EPFL start-up began developing a nanostructured filter to be installed into the ship funnels. The production of nanostructured filters is similar to that of solar cells; thin metal plate, in this case made of titanium, is nanostructured to increase its surface area and the amount of substances. Plates are then vertically and equally distributed to form paths through which toxic gases go. These gases are captured by nanostructured surfaces. This approach is considered as environmentally friendly, because substances, which are captured here, are intended to be recycled. The exhaust gases thus become inert and can be used for further production of, for example fertilizers. Under laboratory conditions, the nanostructured filter is currently able to reduce the sulfur emissions by 1% to 15% of the applicable standards. It is therefore a major improvement in view of the fact that the new standards will require a reduction of approximately 14%.
The nano research currently addresses the problem of how to produce these filters for large surfaces such as fennels of the cargo ships, and at the same time to reduce their production costs. The next step is to create a prototype nanofilter which can be tested in real conditions.