The Ocean as Balance Sheet: Building a Bankable Case for Direct Ocean Capture

When the IRA expanded 45Q to $180 a tonne, Direct Air Capture looked underwritten by Washington. By 2026 the picture is more selective, and that gap is precisely the opening Direct Ocean Capture walks into.

Beyond Subsidies: Why the DAC Setback Opens a Door for Direct Ocean Capture

The One Big Beautiful Bill Act left the 45Q credit itself intact. What it did not protect was the federal grant money behind the flagship DAC hubs, which has been frozen or pulled back. That distinction matters more than the headlines suggest. The per-tonne credit survives; the capital subsidy meant to de-risk first-of-a-kind plants does not. For a technology whose core problem is capital intensity, losing the grant while keeping the credit is the worst half to lose.

That is the opening Direct Ocean Capture (DOC) walks into. Not because subsidies vanished, but because DOC's bankability was never built on a grant in the first place. The question worth an allocator's time is narrow: can DOC reach a tonne cost that clears the durable-credit price without a public cheque, and how far away is that today? The numbers below reconcile to costs that Captura, Equatic and Planetary have publicly disclosed, so every figure can be checked rather than taken on faith.

From Pilot to Commercial Scale: Where DOC Stands in 2026

The signal worth noting in 2026 is that DOC has moved from beaker to build. Based on public company announcements: Equatic is developing North America's first commercial-scale ocean-based removal facility; Captura is commercializing in Japan and adding a 1,000-tonne unit at a gas-processing site in Norway; and a Singapore plant is slated to draw down on the order of 3,650 tonnes a year. Alongside them, Ebb Carbon runs an electrochemical process that both removes CO₂ and reduces local ocean acidity. None of this is at gigatonne scale. But the move from single pilots to first commercial units is the inflection an early allocator underwrites before the cost curve fully bends.

Why Direct Ocean Capture Starts Cheaper Than Direct Air Capture

DAC's burden is thermodynamic. Air is roughly 0.04% CO₂, so a contactor must move enormous volumes to capture a single tonne. Seawater holds dissolved inorganic carbon at a concentration on the order of 140 times that of the atmosphere. Contacting a denser stream means less equipment per tonne, and equipment, not energy, is where the cost actually lives.

This is the correction worth making to most DOC commentary: DOC is not the lower-energy option. Electrochemical DOC (the approach taken by Captura, Equatic and Ebb Carbon) runs around 2.2 MWh of electricity per tonne. That is comparable to, sometimes higher than, solid-sorbent DAC, and it is high-grade electricity rather than low-grade heat. The advantage is not the power bill. It is threefold: lower capital intensity from the concentration gradient, a saleable hydrogen co-product that DAC does not produce, and the option to bolt onto existing water infrastructure instead of building greenfield.

What Direct Ocean Capture Costs Per Tonne Today

Cost component	First plant (today)	Early-commercial	At-scale
Energy (2,200 kWh/t × power price)	$198	$132	$80
Capex (amortised)	$200	$80	$40
Non-energy O&M	$70	$40	$25
Gross before co-product	$468	$252	$145
Less: hydrogen co-product	$0	($61)	($53)
Net cost per tonne	$468	$191	$93
Publicly disclosed anchor	~$475	~$200	<$100

The first-plant column lands within $7 of the ~$475/tonne Captura has disclosed for its Hawaii facility; the at-scale column lands just under the <$100 target Equatic and others have publicly stated. The path between them is a capex-and-co-product story, not a hand-wave. At a $60/MWh renewable PPA with hydrogen sold at $3/kg, a tonne lands near $147 today, already below DAC at any comparable stage.

DAC vs DOC: The Cost Structure That Decides Capital

Put the two side by side on the lines that actually move capital and the story is not energy. It is capex per tonne. DOC's denser feed means less steel for the same tonne, and the hydrogen by-product claws back cost that DAC simply does not have.

Cost line ($/t CO₂)	DAC today	DAC at-scale	DOC today	DOC at-scale
Energy intensity (kWh/t)	1,500–3,000	~1,500	~2,200	~2,000
Energy cost	~$110	~$70	$198	$80
Capex (amortised)	~$700	~$90	$200	$40
Non-energy O&M	~$200	~$45	$70	$25
Hydrogen co-product	n/a	n/a	$0	($53)
Net cost per tonne	>$1,000	~$200	~$475	~$93

DAC line items are illustrative estimates; published DAC cost decompositions vary widely. DOC figures are our build-up, calibrated to disclosed totals. The structural point holds across reasonable assumptions: DAC carries roughly 3 to 4 times DOC's capex per tonne at first-of-a-kind scale.

DOC is not risk-free. It trades DAC's energy-and-capex problem for a different one: ocean alkalinity and pH safeguards, measurement-reporting-verification (MRV) of removals that re-equilibrate over months, and an evolving crediting regime under UNCLOS and national EEZ rules. These are execution and regulatory risks an operator can diligence, not the structural energy penalty that has kept DAC tethered to subsidy.

The Hydrogen Co-Product That Reshapes DOC Economics

Electrolytic DOC co-produces roughly 35 kg of hydrogen per tonne of CO₂ captured. At even a modest $1.75/kg realisation that offsets about $61 of cost; at the $5.50/kg Equatic has publicly targeted it offsets nearly $190. This is what turns DOC from a pure cost centre into a dual-revenue asset, and why pairing DOC with green-hydrogen offtake (feeding synthetic fuels and e-chemicals) is a structural hedge rather than a slideware synergy. The carbon is the product; the hydrogen is the margin cushion when credit prices wobble.

CO2 Plus Hydrogen: From Cost Centre to Feedstock Platform

The hydrogen co-product is one source of value; the captured CO2 itself is another, and it points to the most strategic reframing of the asset. Combine the CO2 a DOC plant removes with green hydrogen and you hold the two inputs for synthetic hydrocarbons, the e-SAF and e-diesel of the power-to-liquid pathway. That turns DOC from a pure carbon-removal cost centre into a feedstock platform with a saleable, oil-linked product, and it lets the same molecule earn twice: once as a durable removal credit and once as the carbon in a drop-in fuel. The two assets also co-locate naturally, a capture unit and an electrolyzer share power, water handling and CO2 logistics, so they reinforce each other rather than compete for capital. The investor point is that DOC need not stand or fall on the carbon-credit price alone; paired with hydrogen it acquires a second, product-based revenue line that the standalone capture case ignores.

Is Direct Ocean Capture Bankable? The Margin Test

Durable carbon removal is being underwritten today. The cleanest public mark is Frontier's offtake with Planetary Technologies for ocean alkalinity enhancement: 115,211 tonnes at $270 a tonne, delivered 2026 to 2030. Against an early-commercial net cost of ~$191, that is a gross margin near $79/tonne, about 29%.

The honest stress test is where this gets useful. If durable-credit prices compress to a $150 floor before costs come down, the early-commercial tonne is underwater by ~$40. DOC's investability therefore rests on a race: riding the cost curve down to the ~$90/tonne at-scale zone faster than premium credit prices erode. Win that race and the at-scale economics throw off $100+/tonne of margin even against a $200 credit. Lose it and you own a subsidy-free business carrying subsidy-era unit costs. Underwrite the curve, not the snapshot.

The Path Below $100 a Tonne, and How We'd Weight It

Cost decline in DOC follows the same Wright's-law logic that fits solar PV (~20% per doubling) and desalination (~12 to 15%). At an 18% rate, which is central rather than aggressive, the model traces first-plant cost from ~$475 toward the ~$90 to $130 band as cumulative capacity passes the megatonne-per-year mark.

Trident's probability weighting (a judgment, not a forecast)

Rather than assert the $100/t target, here is how we'd actually weight the bridge:

• Sub-$200/t at early-commercial scale by ~2028: ~70% likely. Companies are already deploying toward this; the lever is capex standardisation, which is largely an engineering problem.

• Sub-$100/t at-scale by ~2031: ~40 to 45% likely. Requires all three of modular capex, firmed renewable power near $40/MWh, and a monetised hydrogen stream. Any one slipping pushes this out.

• Stuck above $150/t past 2032: ~30% likely. The downside case, where power stays expensive, hydrogen isn't contracted, MRV friction slows deployment, and the learning rate underperforms.

The investable read: the high-probability prize is the sub-$200 early-commercial tonne against today's $270 credit, not the speculative sub-$100. Deploy into the curve early, contract the hydrogen, and you do not need the optimistic case to clear.

How We'd Underwrite a DOC Pilot

If a DOC project crossed our desk, this is the diligence we'd run before committing capital, the same checklist any allocator should apply:

1. Validated MRV. Independent verification of net removals, accounting for months-long ocean re-equilibration and all upstream and energy emissions. No validated MRV, no deal.

2. Power cost and security. Is a low-cost firmed renewable PPA contracted, or is the plant grid-exposed? At what $/MWh does the tonne break even?

3. Hydrogen offtake. Is the co-product hydrogen contracted and at what price, and is it baked into the cost case or only claimed as upside?

4. Capex pathway. Standardised and modular design, or bespoke first-of-a-kind? Is the assumed learning rate defensible against solar and desalination analogues?

5. Permitting and jurisdiction. Alkalinity and pH discharge permits in hand? Is crediting under UNCLOS and the relevant EEZ actually clear, or still evolving?

6. Offtake quality. Durable-credit buyers under contract (term, volume, price floor), or merchant exposure to a volatile voluntary market?

7. Downside survival. At a $150 credit floor and no subsidy, what is the IRR? If the answer is negative, the thesis depends entirely on the cost curve, so size the position accordingly.

How Investors Should Read the Opportunity

DOC is not a moonshot bet on a single breakthrough. It is three linked theses you can underwrite separately: a capex-down learning curve with a credible path below $100/tonne; a co-product hedge DAC structurally lacks; and an infrastructure-integration play (desalination brine, port cooling water, wastewater outfalls) that trims siting and permitting risk by building on assets already moving millions of gallons a day. The ocean is not the next carbon-removal story to chase headlines. For a buy-side operator, it is the one where the unit economics are starting to pencil without a government cheque.

Direct Ocean Capture: Investor FAQ

What does Direct Ocean Capture cost per tonne today?

First-of-a-kind plants run roughly $475/tonne (Captura, Hawaii). A transparent build-up puts early-commercial cost near $190/tonne and an at-scale target just under $100/tonne, driven mainly by falling capex and monetising the hydrogen co-product.

Is DOC cheaper than Direct Air Capture?

On starting cost, yes: DOC's ~$475/t first-plant cost is well below DAC's >$1,000/t today, mainly because DAC carries roughly 3 to 4 times DOC's capex per tonne. The structural reason is concentration, since seawater holds carbon at ~140× the density of air. DOC is not, however, lower-energy.

Does DOC depend on subsidies?

Less than DAC. DAC's case leans on the 45Q credit (up to $180/t, preserved under the 2025 OBBBA, though DAC hub grants were frozen). DOC's bankability rests on durable-credit prices plus a hydrogen co-product rather than a public grant.

What is the hydrogen co-product worth?

Electrolytic DOC yields ~35 kg of hydrogen per tonne of CO₂. At $1.75 to $5.50/kg that offsets roughly $60 to $190 per tonne of capture cost.

Who are the main Direct Ocean Capture companies?

Captura, Equatic and Ebb Carbon lead the electrochemical DOC approaches, while Planetary Technologies is scaling ocean alkalinity enhancement, the pathway behind the 2025 Frontier offtake at $270/tonne.

What are the main risks?

Ocean alkalinity and pH safeguards, measurement-reporting-verification of removals that re-equilibrate over months, and an evolving marine crediting regime. Validated MRV should be a gating diligence item.

Methodology: cost figures are a bottoms-up Trident estimate calibrated to publicly disclosed cost points (Captura, Equatic) and benchmarked against a real durable-credit offtake (Frontier–Planetary). DAC line items are illustrative estimates drawn from public ranges. Probability weightings are Trident's judgment, not a forecast. Assumptions are documented in our DOC economics model and can be re-flexed. This is analysis, not investment advice.