ChatGPT & DALL-E generated panoramic image illustrating the metaphor of pH balance scales in a marine setting.

No, Dumping Tums In The Ocean Won’t Help Climate Change & Why Is Shopify Involved?

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Geoengineering raised its misshapen head today. Someone tagged me on a post on LinkedIn related to a firm that wants to put a common antacid into the oceans to bond with carbon dioxide they’ve absorbed. I nerded out and am deeply skeptical about the entire thing.

That’s a pity, as when I dug through geoengineering a few years ago, I concluded a couple of things. One, that if we have to use solar geoengineering — dumping millions of tons of sulfur dioxide into the stratosphere every year to increase reflectivity — we’d have lost the fight for climate action. It’s treating the symptom, not the cause, and the strong support for it by the fossil fuel industry and the Trump Administration made it clear that they saw it as another way to continue business as usual.

Secondly, that while eliminating anthropogenic greenhouse gas emissions as rapidly as possible was by far the best way to address global warming, another symptom of the excessive carbon dioxide in our atmosphere — reduced alkalinity in our oceans — might require some help.

Ocean acidification implications for shellfish diagram courtesy of US NOAA
Ocean acidification implications for shellfish diagram courtesy of US NOAA

The problem starts with the ocean lagging the atmosphere in carbon dioxide uptake. After a bunch of fumbling around, I estimated that the ocean was well behind the 420 parts per million we were at today and climbing.

The second is what happens with the carbon dioxide that enters the ocean. Some of it is absorbed by seaweed and the like, hence the geoengineering process of ocean fertilization, where nutrients are added to the water to promote growth. Some of it just sits in solution in the water, and often is cycled into deep waters. There’s more to this, as some of the carbon dioxide in solution or in plants returns to the atmosphere. Deep upwelling currents and winds in the Southern Ocean were found to have caused the entire massive area to stop being a net absorber of CO2. Some of that is natural, some of that is due to human caused changes in wind velocity.

And carbon dioxide has a much greater likelihood of being absorbed into solution in colder waters and returned from warmer waters. Human caused global warming is heating the waters too, so the balance of carbon dioxide entering the ocean is changing for the worse for atmospheric carbon dioxide.

But we’re interested in the last place where carbon dioxide goes when it enters the water. Some of it reacts with water to make carbonic acid, reducing the alkalinity of the water, which then changes again into biocarbonate ions. A problem is that this process grabs another carbon atom along the way from a carbonate ion. One carbon comes in with the CO2 molecule but the end of the process has two carbon atoms between the two bicarbonate atoms. Shellfish need carbon atoms from the carbonate ion to make calcium carbonate for their shells. Reduced free floating carbon, thinner shells, mass shellfish extinction, potential collapse of the ecosystem. Oops.

Enter Tums or more specifically, Milk of Magnesia. The first is calcium carbonate, aka pure oyster shells. The second is magnesium hydroxide. Completely different substances, but they have something in common, which is that humans consume them as antacids to reduce stomach acid and address occasional acid reflux.

If you put pure magnesium hydroxide into sea water, it bonds with the carbonic acid to make magnesium carbonate and water. This prevents the last step of the process which takes a carbonate ion out of circulation to be used by shellfish and reduces the alkalinity of the water.

In theory then, you could add magnesium hydroxide to sea water and at least address a symptom of global warming. But you’ll note that this is not drawing down atmospheric carbon dioxide or addressing the carbon dioxide in plants or dissolved in the seawater. In other words, this apparently isn’t removing carbon dioxide from the atmosphere, but like solar geoengineering, might be just another bandaid to prevent the worst of the impacts.

Except for the next bit. More alkaline seawater, all else being equal, absorbs more carbon dioxide. More acidic seawater reduces its absorption of carbon dioxide. By dumping magnesium hydroxide into seawater, we could indirectly increase oceanic uptake of carbon dioxide, which would then go one of the three directions covered. That varies quite substantially with temperature, so if this was a good idea, we’d be doing it in cold northern and southern waters.

Let’s look to the proposed Oxford Principles for Geoengineering.

  • Principle 1: Geoengineering to be regulated as a public good.
  • Principle 2: Public participation in geoengineering decision-making
  • Principle 3: Disclosure of geoengineering research and open publication of results
  • Principle 4: Independent assessment of impacts
  • Principle 5: Governance before deployment

All very reasonable. I like to say that we’ve proven that we can geoengineer our environment because that’s what global warming is, the result of an uncontrolled, ungoverned experiment in geoengineering which we’ve undertaken by massively increasing the levels of carbon dioxide, methane and other greenhouse gases in the atmosphere, mostly by extracting long buried hydrocarbons and burning them.

So will magnesium hydroxide have impacts? Will intentionally screwing with the pH balance of sea water mess with organisms in the water in ways we don’t understand? Early indications are just that, early. A few studies have been done showing that magnesium hydroxide is at least less harmful than other alkaline options, but they are hardly a slam dunk. And while the Oxford Principles are at least written down, it’s not like there’s a part of the UN with the mandate to regulate, govern and enforce adherence to them.

A billionaire could go out tomorrow and do a bunch of geoengineering with their money. A hundred tons of iron dust was already dumped into the Pacific Ocean off of BC by a rogue businessperson in 2012. The most prominent person behind solar geoengineering, David Keith, formerly a researcher and professor at Harvard but as of 2023 at the University of Chicago, has Bill Gates’ ear and funding, and as I’ve noted numerous times, Bill Gates’ climate investments have been mostly wrong headed. It’s not impossible that Gates’ will be convinced that the only way left to solve global warming is to rent a bunch of planes and dump tons of the sulfur dioxide into the stratosphere. He can certainly afford to.

Back to magnesium hydroxide. Would this be a net benefit? Well, the shellfish would appreciate it, but they’d really appreciate a lot less greenhouse gases entering the atmosphere to heat it and the ocean, and a lot less carbon dioxide entering the oceans to steal their carbonate ions. Enhancing the uptake of carbon dioxide in the oceans would lead to more carbonate ion thievery, so this is a big question mark. And biological assessments are deeply unclear.

Enter Planetary Technologies, a Canadian east coast firm that’s doing this. They’ve received almost C$8 million in grants and investments, along with the $1-million CDR XPRIZE milestone award, a competition Elon Musk and the Musk Foundation funded. It also included some money from Shopify which is long on atmospheric carbon drawdown and bought a bunch of carbon offsets off them in 2021. As a reminder, these are voluntary carbon offsets, and as Joe Romm published last year, thats a pretty dubious class of financial instruments. The cost per credit was unstated, but they aren’t selling a lot of them yet. And likely never will.

The timeline is a little unclear. When founded they apparently intended to use magnesium hydroxide and that’s what’s all over their website still. A few questions occurred to me. How much did magnesium hydroxide cost? How much of a carbon debt did it drag alone with it. How much real carbon drawdown would occur per ton of the stuff?

They get their product from Garrison Minerals which seems to be selling it at $500 per ton, so that’s one answer. Call it $700 delivered and put into the ocean.

There are three methods for making the stuff, from mining it at a couple of places like the interior of Russia which appear to be a long way from water, actually making it precipitate from seawater which seems counterintuitive and adding water to magnesium oxide. The processes range in carbon debt from 0.8 tons to 5.6 tons of carbon dioxide or equivalent per ton of product.

Per the CEO and co-founder of Planetary Mike Kelland, a ton of magnesium hydroxide would result in about 1.25 tons of additional drawdown.

Hmmm. If the mined magnesium hydroxide could be delivered to the oceans off of Russia at a carbon debt of 0.8 tons of carbon dioxide per ton of product, it would take 2.22 tons to create a net one ton drawdown. At $700 per ton, that would cost $1,550. That’s not a remotely fiscally viable solution.

And, of course, Garrison Minerals doesn’t get the low carbon stuff because it’s a tiny fraction of the global market. Sea water precipitation is the biggie and its bottom end is 1.6 tons of carbon dioxide and the like per ton of magnesium hydroxide. There’s no break even possible when every ton added to the ocean has a net 0.35 ton addition of carbon dioxide to the atmosphere.

Then there’s the kicker. The entire global market for magnesium hydroxide is only about 15 million tons a year. It’s a lucrative market sure, but when the entire manufacturing is in the millions of tons, it’s not going to turn into billions of tons.

So the magnesium hydroxide, which is what Planetary is selling today and what is literally all over their website and the basis of their current projects, is a non-starter. Is that what they won the X Prize with? It’s unclear, as I couldn’t find their X Prize submission. What they are trying to do now is to turn waste slag alkaline rocks from mining into a pure alkaline substance that can be added to water. Greg Rau, co-founder and CTO, has been researching this for decades, with one 1999 paper I found co-authored with Ken Caldeira, who was formerly advising Gates’ founded Breakthrough Energy Ventures and is now advising Gates Ventures, which resolves to working for Bill Gates much more directly.

Gates, as a reminder, was an early investor in David Keith’s Carbon Engineering, whose only natural market was enhanced oil recovery, is only building one facility which is doing enhanced oil recovery and was recently bought by oil giant Oxy so that they could continue to do enhanced oil recovery with a thin slurry of green paint. Breakthrough also invested in the hipster homeopathic direct air capture non-solution Heirloom. As I said, Gates — and many other climate aware billionaires — has a terrible track record on this file.

The mining tailings premise has some merit. It apparently uses a different process than the magnesium hydroxide process, but dumping alkaline substances into less alkaline solutions will increase alkalinity. Per Kelland again, after spending some time on the dead end of magnesium hydroxide — clearly a dead end from less than an hour of effort on my part, so why they bothered is a question mark — they’ve pivoted to this and are striving for a $50 per ton target for a pure alkaline product derived from mining waste. It’s deeply unclear how much alkalinity would be increased because it’s not directly removing an acid from the seawater.

Any problems with it? Well, yes. Alkaline rock waste from mining can have a lot of nasty stuff in it. Various attempts have been made to reduced acidity of mining tailing ponds with the stuff, but it increases heavy metal bioaccumulators. Generally speaking, solid mining waste is best put in places where it can’t leach nasty stuff into the ground and ecosystem, not dumped into water systems.

On a completely separate site from their website I found this description.

“Planetary Tech extracts key parts of the mine tailings, including metals such as nickel and cobalt (which can be used to produce batteries), and puts the remaining purified metal salt solution into an electrolyser to split it into green hydrogen and alkaline hydroxide.”

So they apparently are now trying to mine solid tailings for valuable metals and alkaline hydroxide. That last is actually a group of hydroxides including lithium hydroxide, sodium hydroxide and potassium hydroxide. To be clear, if this were easy and cheap, a lot of people would be doing this already. And the addition of green hydrogen as a by product doesn’t inspire confidence, although it may explain why they were originally called “Planetary Hydrogen”.

To be scrupulously fair, I can’t find any description from them of what they are actually up to now — remember that their website is still all about magnesium hydroxide —, but I’ll take the chance that this is it based on a couple of comments from Kelland and this reference.

Does this make any sense? Well, if they can extract lithium hydroxide for $50 or less, it’s worth almost $30,000 per ton, so they’d be selling that, not putting it in the ocean. Sodium hydroxide sells for $600 to $1,300 hundred per ton, so once again, if they could make it for $50, they’d be selling it at a massive profit. Potassium hydroxide? $905 per ton.

There are some other alkaline hydroxides like rubidium and cesium, but they are even more expensive.

Do I think that a carbon drawdown firm is somehow going to be manufacturing materials worth hundreds or thousands of dollars per ton for $50 or less and throwing it in the ocean? No. I don’t think they’ll succeed in successfully separating all of the mess of stuff in mining slag and waste at an economic price point. I don’t think that if they do, they’ll throw it in the ocean to sell carbon credits.

If they are able to manufacture millions of tons of these products from mining slag at a very low carbon debt, the best thing that they can do is sell them at a massive profit. A ton of lithium hydroxide has a carbon debt of 5.7 to 17.1 tons of carbon dioxide or equivalent. Selling it to displace brine and hard rock extraction and their emissions is a vastly more virtuous business and one that actually has a business case. Potassium hydroxide has a carbon debt of 1.9 tons CO2e per ton. Sodium hydroxide is about the same. Just sell low carbon hydroxides cheaply, undercut the high-carbon competition, make a massive profit, avoid a lot of carbon dioxide emissions globally and call it a day.

Frankly, after looking closely at the firm today, it doesn’t make any sense. If they keep using magnesium hydroxide, they are adding carbon dioxide, not removing it, and at great expense. If they can manufacture other alkaline hydroxides and valuable metals, they should be promoting that instead of continuing on the carbon drawdown nonsense pathway.

Every ton of carbon dioxide that is avoided is much more valuable than trying to put the trillions of microscopic horses back into the barn after they’ve left. It’s unclear what the X Prize was for, although I considered it a deeply stupid contest regardless, and it’s clear that Shopify did no technical or economic due diligence. The people involved in Planetary Technologies clearly care and are smart, but that doesn’t mean that they’ve ended up in a remotely rational place.

I’m glad I had a trigger to return to my assessment of ocean geoengineering techniques and implications. It gave me the opportunity to dig through the chemical balances and biological implications in more depth, reviewing more studies. But that’s the only value I got out of assessing Planetary Technologies. It’s just another mineral weathering direct carbon drawdown approach that clearly makes no sense, this one with the twist that it’s underwater.



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Michael Barnard

is a climate futurist, strategist and author. He spends his time projecting scenarios for decarbonization 40-80 years into the future. He assists multi-billion dollar investment funds and firms, executives, Boards and startups to pick wisely today. He is founder and Chief Strategist of TFIE Strategy Inc and a member of the Advisory Board of electric aviation startup FLIMAX. He hosts the Redefining Energy - Tech podcast ( , a part of the award-winning Redefining Energy team.

Michael Barnard has 686 posts and counting. See all posts by Michael Barnard