Saving the oceans

This rather long page is in 3 parts:
Part 1: Kelp as Food
Part 2: Kelp as a geoengineering solution to climate change – but at what cost?
Part 3: Ocean Conservation

Part 1: Kelp as Food

  • The claim is that kelp seaweed and shellfish farms could feed 10 billion people all the veggies and seafood they need from vertical (3d) coastal farms! (You don’t actually eat the kelp as kelp – it becomes a food additive in vegan-burger patties etc much like soy beans are in everything.)
  • Where industrial agriculture requires huge amounts of energy to manufacture nitrogen fertilisers and spread around other mined nutrients, and energy to pump fresh water – these kelp farms don’t need any of that. They hang lines from buoys and get everything they need from the sun and nutrients drifting off our land into the sea.
  • They’re far enough out and submerged so that they survive cyclones. But they are still positioned in the 2% of the ocean that is nutrient rich just off our coasts, not the 98% vast open ocean which are nutrient deserts.

Indeed, too many of our agricultural and city zones pollute the oceans with excessive farm and sewerage nutrients. Over fertilisation lets the wrong algal blooms grow which cause dead zones. As the map from Inlet Keeper shows:-

  • Fortunately, seaweed and shellfish farms gobble up these excessive nutrients and could convert them into food. This is different to aquaculture which tries to grow fish in captivity in big pens in the ocean or on land (often relying on ocean-destroying ‘by-catch’ to feed their captive fish).
  • This short 4 minute video summarises the differences.
  • Bren Smith claims an area of Washington State, or 71,000 square miles (or 185,000 km2) could feed the world. This would be spread around the world’s coastlines in that narrow 2% zone. That’s all the nutritious omega 3 seaweed and shellfish we could eat, restoring the health of our coastlines and stimulating the local ocean ecosystems as we spread.
  • Cost? This is a reality check. At this stage these farms are supplying restaurants with sustainably grown oysters, mussels, clams and scallops. It remains to be seen weather they will be affordable in groceries stores, working towards feeding more of us more regularly to work towards that 10 billion goal. At this stage these farms sell at a premium, and do not seem to be in our groceries stores yet.

Seaweed can fertilise farmlands, returning our NPK fertilisers from the sea to the land.

  • As Bren Smith outlines in the TED talk above, he has relationships with local farmers to bring high quality seaweed onto land as fertiliser. That’s a sustainable cycle, as normal erosion drags nutrients off the coasts and seaweed farms bring them back to our croplands.
  • Bren Smith’s TED talk above was back in 2013. While 3d seaweed and shellfish farms have expanded around the UK, legislative opposition and NIMBY groups have slowed expansion in the USA as Scott Lindell explains in his 2020 TED update.

Part 2: Kelp as a geoengineering solution to climate change – but at what cost?

A note on costs: For years I have left the assertions on this page without costings, trusting that sheer industrial scale would bring the price down. Indeed, that is what Kelp Blue aims to do in their Namibia farms. But I could not in good conscience leave this page the way it was without adding the disclaimer that there are questions about the cost of kelp farming that may dampen our enthusiasm for this approach. So while the potential below is still very exciting, it might rely on advances in industrial manufacturing or drone AI or something to bring the costs down. For right now – just growing kelp out in the deep ocean to let it sink to the ocean floor kilometres below seems to expensive! As Technology Review Sept 2021 said:

UC Irvine’s Davis has been conducting a comparative economic analysis of various ways of putting kelp to use, including sinking it, converting it to potentially carbon-neutral biofuels, or using it as animal feed. The preliminary results show that even if every cost was at the lowest end of the ranges, seaweed sinking could run around $200 a ton, which is more than double the long-term, low-end cost estimates for carbon-sucking factories.

So as I outline the wonderful claims – keep those costs in mind. It might just be easier to have nuclear-powered factories sucking the CO2 out of the air on land. However, if a global carbon trading system could be brought to the table – they might fund this out of a desire for the other benefits of stimulating the world’s oceans on such a massive scale. For when a factory has dumped carbon underground, that’s all it has done. But when kelp has done it, you can have biofuel and huge new supplies of fresh fish as well.

Here are the claims: gigantic kelp farms floating out in the 98% deep sea could sequester all our carbon emissionss and solve climate change this century, reduce ocean acidity, and give us many other products as well. These farms would be so big experts put them in the geo-engineering category. They grow out in the 98% nutrient deserts by having solar-powered barges that pump nutrient rich water up from 500 meters below.

As Professor Tim Flannery writes:

The stupendous potential of seaweed farming as a tool to combat climate change was outlined in 2012 by the University of the South Pacific’s Dr Antoine De Ramon N’Yeurt and his team. Their analysis reveals that if 9% of the ocean were to be covered in seaweed farms, the farmed seaweed could produce 12 gigatonnes per year of biodigested methane which could be burned as a substitute for natural gas. The seaweed growth involved would capture 19 gigatonnes of CO₂. A further 34 gigatonnes per year of CO₂ could be taken from the atmosphere if the methane is burned to generate electricity and the CO₂ generated captured and stored. This, they say:

could produce sufficient biomethane to replace all of today’s needs in fossil-fuel energy, while removing 53 billion tonnes of CO₂ per year from the atmosphere… This amount of biomass could also increase sustainable fish production to potentially provide 200 kilograms per year, per person, for 10 billion people. Additional benefits are reduction in ocean acidification and increased ocean primary productivity and biodiversity.

University of the South Pacific’s Dr Antoine De Ramon N’Yeurt

Nine per cent of the world’s oceans is not a small area. It is equivalent to about four and a half times the area of Australia. But even at smaller scales, kelp farming has the potential to substantially lower atmospheric CO₂, and this realisation has had an energising impact on the research and commercial development of sustainable aquaculture. But kelp farming is not solely about reducing CO₂. In fact, it is being driven, from a commercial perspective, by sustainable production of high-quality protein.

A haven for fish. Daniel Poloha/

What might a kelp farming facility of the future look like? Dr Brian von Hertzen of the Climate Foundation has outlined one vision: a frame structure, most likely composed of a carbon polymer, up to a square kilometre in extent and sunk far enough below the surface (about 25 metres) to avoid being a shipping hazard. Planted with kelp, the frame would be interspersed with containers for shellfish and other kinds of fish as well. There would be no netting, but a kind of free-range aquaculture based on providing habitat to keep fish on location. Robotic removal of encrusting organisms would probably also be part of the facility. The marine permaculture would be designed to clip the bottom of the waves during heavy seas. Below it, a pipe reaching down to 200–500 metres would bring cool, nutrient-rich water to the frame, where it would be reticulated over the growing kelp.

Von Herzen’s objective is to create what he calls “permaculture arrays” – marine permaculture at a scale that will have an impact on the climate by growing kelp and bringing cooler ocean water to the surface. His vision also entails providing habitat for fish, generating food, feedstocks for animals, fertiliser and biofuels. He also hopes to help exploited fish populations rebound and to create jobs. “Given the transformative effect that marine permaculture can have on the ocean, there is much reason for hope that permaculture arrays can play a major part in globally balancing carbon,” he says.

The addition of a floating platform supporting solar panels, facilities such as accommodation (if the farms are not fully automated), refrigeration and processing equipment tethered to the floating framework would enhance the efficiency and viability of the permaculture arrays, as well as a dock for ships carrying produce to market.

Given its phenomenal growth rate, the kelp could be cut on a 90-day rotation basis. It’s possible that the only processing required would be the cutting of the kelp from the buoyancy devices and the disposal of the fronds overboard to sink. Once in the ocean depths, the carbon the kelp contains is essentially out of circulation and cannot return to the atmosphere.

Fuel: seaweed to replace oil for airlines?

That’s the claim. Just let that sink in for a moment. Because refineries could turn bio-methane into diesel or jet fuel for the airlines. Unlike other biofuel schemes it does not compete with farmland – and could supply enormous quantities of fuel for say the airline industry. But the economics are unclear. Note that others predict nuclear cracked seawater can provide all the carbon-neutral e-diesel we need, so this comes down to cost.

Tim Flannery TED talk: 17 minutes

Fibre: paper, plastics, pharmaceuticals and concrete!

These gigantic kelp farms could provide us with paper, building products and even seaweed concrete! So grab a coffee and watch the ABC special below.

Tim Flannery 1 hour documentary, “Can seaweed save the world?”

A look at wave-powered ocean pumps

Dr Antoine De Ramon N’Yeurt proposes that wave-powered pumps could bring nutrients up to increase plankton growth, but the same technology could help seaweed.

Part 3: Ocean Conservation

While we are talking about how the ocean can save us let’s also talk about how we can save the oceans. These conservation groups work to create marine parks and save threatened reefs and fisheries and protect the oceans from pollution. I’m recommending these 2 enormous organisations in particular because they also seem to accept the need for nuclear power. (Which is sadly rare in conservation groups these days.) If you love their ocean work, chances are you’ll love their forest habitat protection, wetlands work, and many other areas of environmental protection.

The Nature Conservancy are open to nuclear power.  Click this link to go to their page dedicated to the oceans.


Conservation International seem to allow nuclear power and have a beautiful page dedicated to the oceans.