Why is seaweed suddenly everywhere?

What lies behind the increasing use of seaweed in the world of sustainability?

Regular readers of Springwise may have noticed a trend in recent months – the prevalence of seaweed-based innovations. There have been so many of these that it sometimes feels that seaweed can be used for any purpose.

But really what lies behind the increasing use of seaweed in the world of sustainability?

A few basic facts are driving the growth of these innovations. Many varieties of seaweed grow very fast, seaweed cultivation requires no fertilisers or pesticides, seaweeds contain a large amount of starch and other compounds that act as thickeners, along with vitamins and minerals, and it can be relatively easily polymerised and turned into a plastic substitute.

Uses for seaweed

While different seaweeds have been used as food and as a component in animal feed for many centuries, it is only recently that people have begun experimenting with a much wider variety of uses for this giant algae. Some of these include a natural fertiliser and soil conditioner; biogas; an additive to cosmetics and food; a source of industrial gums used as edible thickeners in food and products such as toothpaste; as water treatment or an agent for removing water acidity; fibres in clothing; and finally, biodegradable packaging.

Researchers have even found an enzyme in seaweed that can be extracted and used as a phosphate-free cleaner, in place of laundry detergent.

With so many uses, it is no wonder that seaweed is everywhere. In fact, a recent report by Global Market Insights predicted that the commercial seaweed market will exceed $87 billion by 2024.

Farming seaweed

Floating seaweed farms are popping up all over the ocean. Traditional seaweed farming generally involves tying seedlings to lines strung between stakes in shallow areas. Today, whoever, more high-tech and less labour-intensive methods are being developed. 

One of the most common is a cultivation rig, consisting of tens of thousands of metres of rope, strung in a lattice-like configuration and hung underwater from buoys. Once the seaweed is grown, the lines are lifted and the seaweed is chopped free. The ropes are then lowered again to allow the seaweed to regrow. 

Companies such as GreenWave are developing complete ocean farming systems that combine seaweed and shellfish farming and require zero input. The farms sit vertically below the surface, producing high yields with a small footprint. At a cost of just $20,000 (€16882) to $50,000 (€42205) to start, they also have a very low barrier to entry.

One word: plastics

While the most common uses of seaweed are as animal feed and fertilisers, there is growing interest in its use as a plastic substitute. New York-based Loliware has developed cups and straws made from agar extracted from red seaweed, and Notpla (formerly Skipping Rocks Lab) has created a range of biodegradable packaging, including sachets and nets, made from brown seaweed. 

SmartFiberAG has created a sustainable process that turns seaweed and plant extracts into fibres that can be woven into cloth. The fibres are made with nanotechnology, which embeds dried, crushed seaweed into cellulose fibres. The cellulose is then broken down and spun into a yarn. The yarn has already been used for everything from reusable nappies to couture clothing.

However, seaweed’s biggest potential may well lie in its use as a substitute for plastic packaging. Compounds can be easily extracted from seaweed and used to create biopolymers — decomposable plastic substitutes. It has been estimated that just 0.03 per cent of the brown seaweed in the oceans could replace a year’s worth of PET plastic bottles. 

Plastics made from seaweed decompose in a matter of weeks. The seaweed also fixes nitrogen and carbon dioxide as it grows, making an efficient carbon and nitrogen sink. Earlier this year, Notpla teamed up with Just Eat to launch the world’s first takeaway box lined with plastic derived from seaweed. This may sound small, but the takeaway industry is estimated to use around 500 million plastic boxes each year.

While making bioplastic from seaweed is relatively straightforward, researchers are also searching for ways to make the process greener. A team in Israel has recently developed a way to make plastics not from extracts of seaweed itself, but from microorganisms that feed on seaweed. The microorganisms eat the algae and produce a polymer that can be used to make bioplastic.

Seaweed-based bioplastics could have a myriad of uses other than packaging. Gordon Wallace, a professor from the Intelligent Polymer Research Institute at the University of Wollongong, uses alginate extracted from brown algae to 3D print soft tissue to aid in wound healing.

A new biogas 

The other major use of seaweed is as a source of biogas. Although biogas is considered a greener alternative to petroleum-based fuels, many biofuels are made from food crops, such as corn and soy, which require fertilisers, water and pesticides. Their use as fuel can also drive up global food prices and still produces large amounts of CO2. Seaweed-based biogas, in contrast, has none of these downsides. 

Researchers in a number of countries are working on ways to convert seaweed into biogas. Last year, a team in Mexico developed a prototype system that uses sargassum. They mix the cleaned and dried seaweed with a fungus that breaks down the lignin in the seaweed and generates methane. This biomethane can then be used as a fuel source for cooking, heating or even generating electricity. A number of researchers are also working on cost-effective ways to convert seaweed into bio-briquettes. 

At some point in the near future, we could all be wearing clothes made from seaweed; washing those clothes with detergent derived from seaweed; cooking with seaweed-based gas and storing the leftovers in containers made from seaweed; sipping our drinks through seaweed straws, and slapping on a seaweed plaster if we cut ourselves. The possibilities are seemingly endless.