What’s happening? An Oceans of Energy development off the coast of the Netherlands has become the first aquaculture project powered by floating solar technology. The 50KW PV-powered plant, developed in collaboration with the Seaweed Company, extends across six square kilometres and builds on the Zon-op-Zee pilot which ran in 2019. The seaweed farm is part of the European H2020 United project designed to encourage “sustainable and multi-use offshore systems” in EU waters. Why does this matter? Growing at 8% a year, the seaweed market is gaining interest globally and expanding rapidly in areas including the US and Europe due to potential applications in several sectors. The Oceans of Energy multi-use offshore development utilises space in between its photovoltaic (PV) panels to grow seaweed, which is collected by the Cultivator – an offshore harvesting machine that is expected to produce around 15,000 kg of seaweed, which would absorb around 1.8 mt of CO2. The high-wave floating PV panels powering the farm are built for stormy conditions, and can operate under 13-meter-high waves. Other multi-use offshore developments are being explored in European waters. The European Union’s H2020 United Programme, which supports the Oceans of Energy project and which launched last year, aims to demonstrate the viability and advantages of combining offshore energy projects with aquaculture or tourism, through five real-life pilot applications. Other pilot sites supported by the project include flat oyster bed restoration and seaweed cultivation at an offshore farm operated by Parkwind in Belgian waters. The aquaculture of flat oysters is expected to aid the restoration and growth of natural oyster reefs, which will be encouraged by the scour material used around the wind turbine foundations. Elsewhere, Dutch firm Van Oord has planned to install eight oyster reef structures at the Borssele offshore wind farm as part of a project designed to revive oyster populations and marine biodiversity in the North Sea. Co-locating aquaculture developments, such as seaweed farming, with offshore projects can prove to be economically beneficial by taking advantage of unused marine spaces, and can also provide affordable access to food, energy and jobs to remote communities. There are many potential uses for algae alongside human consumption. These include reducing emissions from livestock – firms such as Australia’s FutureFeed are looking to commercialise an Asparagopsis seaweed-based livestock feed additive, which successfully reduced methane emissions from cattle by over 80% in trials. Seaweed is being developed into biodegradable packaging by Oceanium for food products as a plastic alternative. Meanwhile in the UK, researchers from the University of Liverpool are investigating the anti-viral qualities of seaweed and future uses in sustainable disinfectant products, while researchers from the University of Exeter and Bath have converted the invasive seaweed Sargassum into bio-oil. From a market perspective, the future of these sea plants looks promising. The European seaweed market is forecast to be worth €9bn ($11bn) by 2030 – and regenerative seaweed farming can play a possible role in a green post-pandemic recovery as well as in the European Green Deal. In Australia, the industry could be worth AUD 1.5bn ($1.2bn) by 2040. The private sector is also taking an interest – a WWF’s seaweed farming project received a $100m grant late last year from Jeff Bezos’ $10bn Earth Fund in recognition of its environmental benefits. It's important however this growth comes with checks to make sure there are no adverse consequences to the wider marine environment – the ecological consequences of large offshore seaweed farms are still relatively unknown.