GreenWave – Taking ocean farming to new depths

GreenWave has pioneered a vertical ocean polyculture that produces high yields of seaweed and shellfish with a low environmental footprint. Their farming system restores marine ecosystems and is both open-source and easily replicable at a fairly low cost. Part of a "Regenerative Reef" – or a commercial and a processing hub, it's also financially viable by design, championing the livelihood of coastal and indigenous communities. This 360° approach sets GreenWave apart.

Challenge: Eating in harmony with the world underwater

Against the backdrop of climate change and overall environmental degradation, oceans are often categorized as victims of warming, acidification, pollution, and vanishing species. They also instill fear as rising sea levels threaten food security and livelihoods. Economic inequalities facing coastal communities are another cause for concern. Regenerative ocean polyculture offers a powerful solution to these issues.

Until recently, researchers and investors alike paid little attention to the ocean’s own formidable potential to address these challenges. But as aquaculture becomes the fastest-growing food sector, the industry is under increasing scrutiny. And rightly so! Today’s conventional ocean fish cultivation, much like land-based agriculture, has many ecological drawbacks. One of them is the accumulation of excess nitrogen and phosphorus from feeds and fertilizers, causing dead zones in the oceans.

“Regenerative ocean farming is one of the most nutritionally, socially and environmentally sustainable food productions on the planet.”

Coincidentally, seaweed and shellfish have the distinguishing feature to feed on some of the excess nutrients to fuel their growth. They also capture part of the 25% atmospheric carbon oceans absorb every year. On top of buffering ocean eutrophication and acidification, growing sea greens and bivalves together in a polyculture system contributes to healthier marine environments. It provides diverse species with forage, refuge, and spawning habitats. This safe haven results in a 40% to 360% greater abundance of fish and invertebrates and up to 30% more biodiversity.

This regenerative mariculture can also bring about systemic social change. According to a World Bank study, farming seaweed in just 0.1% of the world’s oceans – about 40 million hectares – could create 50 million jobs. That coastal and indigenous communities have long cultivated mollusks and harvested wild seaweed is a tremendous opportunity to create an equitable blue economy driven by those most affected by changing climate and declining capture fisheries.

Nutrition-wise, despite low-calorie counts, seaweed and bivalves are incredible sources of the much sought-after protein and omega-3 fatty acids. The foodstuffs are also rich in potassium, iron, zinc, iodine, and multiple vitamins. All in all, regenerative ocean farming is one of the most nutritionally, socially, and environmentally sustainable food production on the planet.

Mussels socks
GreenWave’s regenerative ocean farming system grows a mix of seaweeds and shellfish that require zero inputs while sequestering carbon and rebuilding reef ecosystems. Photo: GreenWave

Initiative: GreenWave takes ocean farming to new depths

Co-founder Bren Smith trailblazed vertical ocean polyculture in near-shore locations. In his own Thimble Island Ocean Farm, he perfected the cultivation of 100+ strains of climate-resilient seaweed and shellfish growing in a symbiotic relationship. Kelp, scallops, and mussels hang on nets from 2 meters below the ocean’s surface, while oysters and clams lay on the seafloor. And there’s more than meets the eye.

“GreenWave adds zero fertilizer, feed, freshwater nor pesticide to the ocean, keeping traditional aquaculture’s hefty environmental bill at bay.”


Smith adds zero fertilizer, feed, freshwater, nor pesticide to the ocean, keeping traditional aquaculture’s hefty environmental bill at bay. That’s because the farm uses a sensor technology to find temperature and nutrient “sweet spots” in the water, dropping and lifting farms as needed.

Once the original farm well-iterated, the former cod fisherman co-founded nonprofit organization GreenWave with food system researcher Emily Stengel to share his learnings with future marine farmers. Now, together with scientists, chefs, farmers, and others, they adapt his vertical ocean farming methods to different climates and ecosystems. Their goal is to train 10,000 farmers occupying 400,000 hectares worldwide.

Key facts

  • Winner: GreenWave
  • Type of organization: Nonprofit
  • Year of establishment: 2014
  • Headquarters: Connecticut, USA
  • Founders: Emily Stengel and Bren Smith
  • Number of staff: 17
  • The big idea: A high-yield ocean polyculture that absorbs excess nutrients, restores marine ecosystems and champions coastal communities’ livelihoods
  • Goal: Train 10,000 farmers cultivating 400,000 hectares worldwide.

Ecological and yield win-win

An entry-level eight-hectare GreenWave farm has a far greater capacity to mitigate climate change than an average land-based farm. It absorbs 250,000 tons of CO2 and 300kg of nitrogen yearly. Kelp, for example, captures five times more carbon than land-based plants, while one single adult oyster filters almost 200 liters of ocean water daily by pulling nitrogen out.

These ecological benefits do not come at the cost of productivity. Quite the contrary! Farming vertically delivers high yields on a small footprint for large- and small-scale farmers alike. The same eight-hectare farm produces around 60 tons of seaweed and 90 tons of shellfish annually.

Bren cranking up the kelp line

Economically sound

GreenWave’s farming system is replicable at a fairly low cost, too. Ten times lower than a typical American (Maine) mussel farm, in fact. $ 20,000-50,000, one boat and 8 hectares, can fund a farm. That growers use the same infrastructure to harvest both shellfish and what the nonprofit calls sea vegetables is one of the many cost-saving advantages of the system. Altogether, production costs are low, waste minimal, and good return on investment.

“The annual net sales value of U.S. $ 100,000 speaks volumes about GreenWave’s potential to contribute to the blue economy of tomorrow.”


Cultivating several species indeed allows farmers to harvest crops all year round. Hence a steady income stream even if some fail.

Beyond food, commercial opportunities can be as vast as the oceans. Seaweed-based feed can curb cattle’s methane emissions by 80%. Converted into fertilizer and compost, the marine vegetables bring back to land excess nutrients soaked in the ocean in a virtuous blue-green economy. They can also be transformed into bioplastic packaging.

To scale, GreenWave cultivates a “regenerative reef” model in new regions. Each reef includes 25 to 50 ocean farms with a processing hub, a land-based hatchery, and a ring of institutional buyers. Experts predict that the seaweed snacks market alone will represent $2,909.90 million by 2027 as consumers search for eco-friendly sources of nutrients.

Ensuring equitable access to kelp seeds, GreenWave’s hatcheries strategically fall under the nonprofit organization.

Scaling through training and capacity-building

Since launching GreenWave, Bren Smith’s farm serves as a floating classroom where his team tests new farm designs and technologies to help farmers scale their operations. The farm design itself, which is made up of rope scaffolding and buoys, is simple, and that’s what makes it scalable.

“GreenWave aims to train 10,000 farmers working cultivating 400,000 hectares worldwide”.


To that end, GreenWave provides an array of seed-to-sale support ranging from digital toolkits to hands-on internships. Since launching its first regional training program for regenerative ocean farmers in 2017, the non-profit has trained and supported more than 970 emerging ocean farmers, hatchery technicians, and entrepreneurs across the United States. But to onboard all 8,000 people currently on their ever-sprouting waitlist and reach their 10,000 farmers goal, the nonprofit needs to gear up.

In July, it soft-launched a farm design and optimization tool for 530 previously trained farmers. They plan to roll it out to the public in Spring 2022. The content initially addresses the needs of North American farmers but will gradually cover other regions. The portal will also feature a collaboration hub tailored for mutual learning and a co-op, where growers can negotiate with distributors and aggregate blue carbon offsets.

Furthermore, fully aware of the challenges of operating in an early-stage industry, the pioneer organization supports stakeholders in carving new regulatory pathways to adopting regenerative mariculture and overcoming market barriers. For instance, GreenWave helped incubate Akua, a producer of kelp-based burgers, pasta, and jerky.

A plate of kelp noodles

Potential drawbacks

While regenerative ocean farming overwhelmingly offers positive environmental impacts, potential concerns include invasion of non-native species as well as gear pollution and marine mammal entanglement. However, incidents in near-shore – as opposed to offshore – farms are rare.

In addition, through training and tools, GreenWave promotes strict adherence to practices that dramatically minimize gear loss and invasion.

Going global: scaling deep before scaling broad

As requests to start farms are pouring in from over 100 countries, GreenWave has cautiously begun expanding programming beyond the U.S. coastline. For example, in New Zealand, they’ve worked with local partners collaborating with the Māori communities to build a business case for the potential of the regenerative ocean farming system to support local economic, social justice, and ecological goals. A pilot farm is about to be launched with native brown kelp in an existing mussel farm.

In Puerto Rico, they are partnering with the Woods Hole Oceanographic Institution to explore warm water species farming.

What would GreenWave do with the Prize sum?

GreenWave would invest the Food Planet Prize money in accelerating the achievement of its 10-year goal: providing tools, support, and training to a baseline of 10,000 regenerative ocean farms. The funds would go to GreenWave’s online farmer community dashboard and marketplace, as well as high-touch training for Indigenous and coastal communities to put them at the forefront of the new blue food industry.

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