Sustainable biofuels from the sea

Seaweed Energy Solutions is one of the first companies to cultivate large-scale seaweed for biofuel production. They offer an integrated solution, from the development of better seaweed strands to technologies for anchoring and harvesting the seaweed.

Bionergy: Fast-growing seaweed can be the new source for sustainable fuels

Biofuels are one of the most debated and disputed renewable energy sources. While the technology is a key to more sustainable transport, it has been claimed to inflate food prices and encourage deforestation. Shifting production from land to sea might just avoid some of these issues.

Competing with food
The main challenge with land-based biofuels is that they derive from plants grown the same places as we can grow food. One of the cheapest ways of producing biofuel is from palm oil, grown on plantations. Unfortunately palm plantations grow best where there used to be rainforest. When biofuels enter the market as a competitor to petroleum, they also compete in price. When oil prices rise, the price on biofuels can rise correspondingly, and farmers will see it more profitable to grow plants for biofuel production than growing food. Land-based biofuels therefore have the possibility to connect food prices to oil prices even more strongly than they already are, which can have devastating effect in poverty-stricken regions.

Bioenergy from the sea
The Norwegian start-up Seaweed Energy Solutions (SES) offers a way around this problem. The oceans cover 73% of our planet's area, and half of all photosynthesis occurs in the sea. So, they asked themselves, why are all biofuels made from plants on land?

Many Asian countries have long traditions with cultivating sea vegetables for food. They use ropes stretched out over the sea floor and taken up when they're covered with plants. SES is trying to make this procedure both more efficient and more environmental. By planting seaweed spores on large submerged flake-like structures anchored to the sea floor, they enable a denser growth that is easier to harvest. Because seaweed grows best in turbulent waters, the flakes act like giant leaves swaying in the current. After harvesting, the plants are placed in tanks to rot and produce biogas, or to ferment and produce bioethanol.

As the flakes are placed in the middle of the water column, where no plants grew before, they are not competing for space. Rather, they create a new habitat for fish and other sea creatures. In many places, wild seaweed is diminishing along the coasts, something this could help counterbalance.

 
Seaweed are planted on large leaf-like flakes. Photo: Seaweed Energy Solutions

Carbon storage
With every rainfall, nutrients are washed out of the soil and transported to the ocean. This is a natural cycle, but with intensive farming and heavy use of fertilizer, the seas receive a much larger amount of nutrients than they would naturally. These nutrients accumulate along the coast, leading to algae blossoming and oxygen depletion, which kills off other sea life. Seaweed acts as a bio-filter, absorbing nutrients and pollutants, thereby making the water more oxygen-rich.

Seaweed grows faster than plants on land. This is partly because they can capture nutrients like nitrate and phosphate not only in their roots, but from their entire surface. The brown seaweed used by SES grows up to 3 meters in 8 months. As with any other plant, they grow by using photosynthesis to produce sugar from carbon dioxide. Increased carbon dioxide concentrations in the atmosphere has lead to an acidification of our oceans, which threatens many marine organisms. A large-scale deployment of seaweed cultivation could work as a natural carbon capture and storage mechanism that reduces this acidification process.

Going commercial
After several successful tests off the coast of Norway, Seaweed Energy Solutions is optimistic about the future. According to them, if just 0,05% of the area off the coast of Europe was used for biofuel production, it could cover 1,6% of Europe's fuel consumption, or 20 TWh per year. To use our marine areas efficiently, they suggest introducing seaweed farms around existing installations such as oil rigs, and around fish farms to absorb waste and nutrients. The only challenge now is to make the technology commercially viable. They hope to achieve this within the next three years.