By Dr. Torill, Bigg – Tunley Environmental

Seaweed provides natural carbon sequestration, habitats for biodiversity and coastal protection.

The farming of seaweed embraces and retains these environmental benefits while providing eco-friendly products, employment, and economic activity. Globally, the intensity of seaweed farming has accelerated rapidly this century (Food and Agriculture Organization). Yet the full potential of seaweed is far greater still. This is especially true in Europe, which has only 0.8% of worldwide seaweed farming production.

European countries face complex and simultaneous challenges such as climate change, sea-level rise, economic instability, and unsustainable fishing practices. Against this backdrop, seaweed farming holds great promise, offering a sustainable, multifaceted approach to tackle these issues. Leveraging the benefits of seaweed farming would help stimulate local economies and contribute to environmental protection and climate change mitigation.

Carbon stored in marine and coastal ecosystems is known as Blue Carbon. Seaweed farms, as a part of these ecosystems, can play a significant role in carbon sequestration. Because seaweeds grow rapidly and have significant photosynthetic activity, combining light and carbon to fuel that growth, they absorb substantial amounts of carbon dioxide, and lock it into a solid form. This can then be harvested or allowed to sediment into the seabed. Seaweeds are 20 times more effective at this than land plants. Several countries, including China, Indonesia, and the Philippines, have made seaweed-based carbon sequestration an integral part of their strategies for climate change mitigation.

Maybe in part because of this strategy, there is a greater volume of seaweed farming in Asia than in Europe. European seaweed farming schemes however are on the rise. In the UK seaweed businesses doubled between 2016 and 2023. For seaweed farming to contribute an appreciable difference to carbon emissions requires a massive scale-up from pilot projects to kilometer-scale farms. This would entail the welcome necessity of investment in people’s skills and knowledge and increased funding for seaweed businesses. Ongoing research into the ecosystem benefits and possible negative consequences of large-scale seaweed farms is also needed to ensure that large farms do not inadvertently harm local marine fauna and flora or the local communities too. And a balance would need to be found in order to deploy the maximum benefit from seaweed farming in removing carbon from the atmosphere while stimulating the economy.

Further to the benefits of carbon storage, wildlife habitats, climate change mitigation, increased economic activity are those of water quality and coastal protection.

Water quality is impacted by increasing populations and coastal development. These lead to elevated aquatic nutrient concentrations from sewage and agricultural runoff. This enrichment can cause Harmful Algal Blooms (HABs) which are an explosive growth of phytoplankton. These cause significant ecological disruptions where oxygen is depleted, there is death of marine life, and the release of toxins. HABs can also cause severe economic damage. Fishery businesses are badly impacted, coastal tourism is hugely reduced, local leisure and quality of life is affected as beaches are closed and local trade loses the related revenue. The nature of seaweed farming lowers the concentrations of nutrients and increases dissolved oxygen in waters where the seaweed is grown. This reduces the impact of nutrient enrichment and providing a buffer against excessive phytoplankton growth. By acting as an effective biofilter, seaweed can also play a crucial role in maintaining water quality in the face of escalating anthropogenic particulate loads.

Coastal erosion can pose a significant threat to coastal communities and infrastructure. Strategic deployment of seaweed farms can provide cost-effective, eco-friendly natural measures to help safeguard them. Seaweed grown around the coastal area, as with seaweed farms, reduce the energy of waves and so diminish their erosive power.

Seaweed farming, then, would bolster the health and resilience of marine ecosystems, and reduce the toll associated with HABs and coastal erosion.

Seaweed farming can be used for both food and non-food products. For hundreds of years seaweed has been cultivated for food, animal feed and soil treatment. More recently seaweed has been utilized in cosmetics, medicine, and food supplements. Seaweeds have an attractive savory flavor, offer fiber, antioxidants, and iodine, are low in fat, and have a range of micronutrients such as omega-3 and omega-6 polyunsaturated fatty acids, vitamins. Seaweed consumption can also have important health benefits such as providing calcium, lowering blood pressure, and preventing strokes. And yet, seaweed has not traditionally been seen as an attractive food crop. Development of a significant edible seaweed industry requires greater awareness of the culinary potential and numerous health benefits seaweed provides.

Seaweed is also a viable feedstock for livestock and can be grown with a reduced environmental impact relative to traditional crops. As an example, soybean farming uses the same land area as the Netherlands, Belgium, France, and Germany combined, and is the second largest driver of deforestation. Seaweed requires no added fertilizer and does not require a change of land use. As a livestock feed, certain seaweeds have been shown to significantly reduce methane emissions from ruminants. Methane is a much more potent greenhouse gas than carbon dioxide and studies suggest that supplementation of the seaweed Asparagopsis into cattle diets could save 2.6bn tonnes of CO2 equivalents a year by 2050.

Further to these products seaweed also has potential as biofuel, in textile manufacture and, as a fertilizer. In 2013, over 4% of global agricultural land was used for biofuel production. This figure is both likely to have risen over the past decade and could continue to rise as countries increase biofuel use for climate mitigation. Such change of land use decreases biodiversity and increases atmospheric carbon concentrations. Seaweed is an especially promising alternative to the use of traditional biofuel crops such as corn and sugar cane, as it does not compete for land, grows very rapidly, does not require fertilizer, and can benefit the aquatic ecosystem. Seaweed can be simply combusted in its entirety or can be converted into secondary biofuel products such as bioethanol, biogas, biodiesel, and biohydrogen. Derived biofuels have greater energy density than entire seaweed, allowing it to be used in a variety of contexts, such as transport, shipping, and even aviation. In the UK, with its extensive coastline and marine resources, the development of a seaweed-based biofuel industry could contribute to energy security while simultaneously reducing greenhouse gas emissions. Furthermore, seaweed biofuel production could create jobs, particularly in coastal communities, stimulating economic growth and speeding the transition to a low-carbon economy.

Seaweeds are versatile and can be used as an alternative to plastics, plastic packaging, textiles, and other typically carbon-intensive, unsustainable products. Seaweed-based membranes manufactured from edible, biodegradable seaweed carbon be used to store water and to package food. Seaweed-derived yarns can be used for weaving sustainable textiles, and seaweed leather products which can replace both animal-based leather as well as land-grown vegan leathers.

The seaweed farming industry has great potential for job creation and economic security. Traditional fishing communities have grappled with challenges of overfishing, climate change-induced shifts in fish populations and economic precarity. Large-scale seaweed farming could be a sustainable alternative providing a new source of livelihood that is more reliable and more environmentally friendly than fishing.

Several businesses around the UK are already realizing the benefits of seaweed farming from both environmental and economic perspectives. For instance, Câr y Môr is a Welsh community-owned company driving sustainable aquaculture through the combined farming of mussels and seaweed off the Pembrokeshire coast. Predominantly selling the seaweed for food, they seek to harness the low impact, fertilizer-free farming of seaweed. By farming seaweed alongside shellfish, Câr y Môr can create year-round, sustainable aquaculture and provide a consistent income for its members. The Cornish Seaweed Company is another example of a small UK company using seaweed farming to sustainably produce food products and benefit a coastal community by reducing their reliance on tourism.

Continuing to expand the seaweed farming industry would stimulate job creation across multiple sectors—from farming and harvesting to processing and product development. Seaweed farming requires only a very modest initial investment, needing significantly less human input and none of the expensive land, fertilizers, or irrigation of terrestrial agriculture. These make it a highly accessible opportunity for communities that might not otherwise have the resources for extensive farming setups.

Moreover, the potential socioeconomic benefits of seaweed farming extend beyond the borders of developed countries like the UK. Where communities are more directly dependent on the health of their marine ecosystems, seaweed farming can provide a significant boost to both economic and environmental resilience. By offering a sustainable source of income and food, as well as contributing to healthier marine ecosystems, seaweed farming could play a pivotal role in supporting sustainable development and climate resilience globally.

Dr. Torill Bigg, Chief Carbon Reduction Scientist, Ph.D. CEng

Dr. Torill Bigg, Tunley Environmental.

Torill is the Chief Carbon Reduction Scientist at Tunley Environmental and leads the carbon reduction team. Torill is passionate about environmental protection and decarbonization; she delights in mentoring the carbon reduction team and takes pride in their outstanding achievements and the quality of their work.

With much experience in engineering design, innovation, operational and asset management, and an academic background in biochemistry, chemical engineering, and business management, Torill continues to apply creative problem solving and leadership skills to her role as the Chief Carbon Reduction Scientist at Tunley Environmental.