A new potential source of biofuel has been identified, the common marine filter-feeding animals known as tunicates. The idea, according to the researchers involved, is that the animals can be harvested with their varying components being used for different purposes. The cellulose that is found in the animal’s mantle can be used to make bioethanol, and the animals’ bodies can be used as fish feed for aquaculture, as they are high in proteins and fats.
While the animals are very common throughout much of the world, “on the ocean floor, under the pier, and on ship ropes,” as the researchers note, they are not very connected to the food chain, as they are filter feeders with no known predators (beyond some humans). The researchers argue that because of this, the large-scale harvesting of the animals would likely not have negative impacts on ecosystems… but that’s quite an assumption.
Even in the absence of animals dependent upon them as a source of prey, species contribute to ecosystems through a variety of means, including acting as “compost” after their death. It very well may be that they can be harvested without significant (noticeable) negative impacts, but it is a hard thing to predict. Some varieties of tunicate are already harvested by people as a food item in parts of Asia. So perhaps studying some of those areas could provide some insight.
One of the primary reasons that the researchers have been looking at the potential uses of tunicates is that they are predicted to become much more common in the coming years as a result of climate change. So they may become a valuable resource.
The researchers note that there are significant advantages to the use of tunicates rather than conventional sources of bioethanol. “The bioethanol used today is unsustainable as it comes from foods already used for human consumption. That is why there has been a move towards using cellulose from the timber industry to produce bioethanol,” says Dr. Sc. Christofer Troedsson of Uni Research’s Molecular Ecology Group and head of the research at the University of Bergen’s Marine Development Biology.
“However, it is quite complicated to break down the cellulose in trees and convert it into ethanol. This is because the wood contains a substance called lignin, which is hard to separate from the cellulose. Tunicates contain no lignin. Their cellulose is also low in crystals and is more efficiently converted into ethanol,” he says.
The researchers have so far focused on one particular type of tunicate, ascidiacea. “Its mantle consists of cellulose, which is a collection of sugars. When cellulose is cleaved, one can obtain ethanol. And ethanol can be used for biofuel in cars. The animal’s body consists of large amounts of protein and Omega-3. This can be used for fish feed,” says Professor Eric Thompson at UiB’s Department of Biology.
Patents have already been obtained for the biofuel process and there is a patent pending for the cultivation of ascidiacea as fish feed.