Seaweed Cultivation Could Provide a Promising Source of Sustainable Aviation Biofuels, Finds Norwegian Report
(GreenAir Online) Seaweed could become a promising source of biofuels for aviation if sustainably produced and economic and policy challenges can be overcome, says a report by Norwegian NGO Bellona. Seaweeds, or macroalgae, generally contain high amounts of carbohydrates (sugars) that make them highly suitable for bioethanol and biobutanol production, where the sugars are fermented. They belong to the fastest growing species in the world and growth rates far exceed those of terrestrial plants, plus the rapid growth also means they absorb significant amounts of CO2. Most importantly, they do not compete for valuable land space or fresh water during cultivation as do many crops grown for biofuels. Industrial seaweed cultivation, where it is mainly used in food production and pharmaceuticals, is largely confined to Asia whereas in Europe it is in the very early development phase. However, says the report, there is a golden opportunity to design a high-potential sustainable aviation biofuel industry effectively from scratch.
This is especially the case in Norway, whose coastline stretches 21,000km, equivalent to 2.5 times around the equator, and encompassing an area of 9 million hectares. The temperate waters that stretch from Portugal to Norway are also highly suited to certain species of brown kelp seaweed, in particular sugar kelp.
The carbohydrates are mainly glucose, galactose and mannitol. The low lignin content of seaweed eliminates many of the challenges faced by wood-based bioethanol producers, as lignin hardens the cell walls and requires pre-treatment before fermentation. Also, as compared to forest/woody biomass, seaweeds’ higher growth rate means there is a higher turnover rate and they could theoretically be cultivated inexhaustibly.
Giant kelp grows faster than bamboo at about 7-14cm per day – even up to half a metre under ideal conditions – with sugar kelp grown in UK waters being shown to grow 1.1cm per day, equivalent to reaching over 2.25m in a year.
Furthermore, seaweed is incredibly efficient at taking up nutrients such as nitrogen and increasingly scarce phosphorus, which it absorbs with comparable efficiency to a waste-water treatment plant. This eliminates the need for fertilisation and, in fact, cultivation of seaweeds in practice means recapturing nutrients into biomass that in turn can be reused for fertilisation purposes. When cultivation is located in proximity to fish farms, seaweed can use the excess, otherwise wasted, nutrients and thereby ensure recycling and cleaning of the surrounding waters.
The study was funded by a grant from Norwegian state-owned airport operator and air navigation service provider Avinor. By 2030, Avinor has targeted that 30% of all jet fuel sold in Norway should be sustainable alternative fuel, which will require 350-400 million litres of jet biofuel annually. READ MORE and MORE (Salon.com) download report