Senken and Carbonsate Sign 50,000-Tonne Deal, Europe's Largest Biomass Storage Offtake

Senken and Berlin-based Carbonsate have signed a multi-year offtake agreement covering 50,000 tonnes of permanent carbon removal between 2026 and 2028, described as the largest biomass storage deal signed in Europe to date and the largest buyer commitment for a project operating in Africa. The credits come from Carbonsate's biomass geological storage project near Otjiwarongo, Namibia, verified under the Puro.earth standard, with Isometric certification under evaluation. Senken says the entire permanent carbon removal market has delivered approximately 1.5 million tonnes to date, meaning this single commitment equals roughly 4 percent of everything the sector has produced so far.

 

How Storing Wood Underground Achieves Permanent Removal Without Energy-Intensive Capture

 

Biomass storage, also known as biomass burial, works by sealing waste wood in engineered underground chambers where it cannot burn or decompose, keeping the carbon it contains locked away for centuries rather than releasing it back into the atmosphere as it would through natural decay or burning. That mechanism distinguishes biomass storage from carbon capture technologies like direct air capture, which require an energy-intensive process to pull carbon dioxide directly from ambient air before storing it. Because biomass storage instead prevents already-existing biogenic carbon in wood from being released in the first place, it avoids that capture step entirely, which is why the release states it delivers permanence at a fraction of direct air capture's cost.

That cost advantage is a significant factor in the durable carbon removal market, where direct air capture has historically commanded premium pricing precisely because of its energy requirements, giving lower-cost, comparably durable alternatives like biomass storage a genuine commercial opening as buyers seek permanent removal options at more accessible price points.

 

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Why the Namibia Project Delivers a Dual Environmental Benefit

 

Carbonsate's project targets a specific ecological problem in the Namibian savanna: encroacher bush, woody vegetation that has spread across former grassland over decades, has been reducing biodiversity and lowering groundwater recharge in the region. Clearing that bush restores rangeland ecosystem function, but the harvested wood would ordinarily be burned or left to decay, releasing its stored carbon back into the atmosphere either way. Carbonsate's approach instead diverts that harvested wood into underground storage, converting a routine land management practice, bush clearing, into a carbon removal mechanism rather than treating carbon storage and ecological restoration as separate, unrelated activities.

Namibia's arid climate is specifically suited to this storage method, providing conditions favourable for dry, stable underground storage of the wood over the multi-century timescales the technology depends on for its permanence claims.

 

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Why the Scale Relative to Total Market Supply Matters

 

Framing this single 50,000-tonne commitment as equivalent to roughly 4 percent of the entire permanent carbon removal market's cumulative delivery to date underscores how genuinely scarce verified permanent removal capacity remains, even as corporate demand for it accelerates. Senken chief executive Adrian Wons framed that scarcity as the defining dynamic likely to shape the market over the coming decade, with demand for permanent removal outrunning the small pool of verified capacity currently available.

That scarcity is why Senken pursued a multi-year commitment rather than a shorter-term or spot-market purchase, since securing volumes years ahead of delivery gives corporate buyers price and supply certainty in a market where available capacity is limited and demand is rising, driven partly by regulatory pressure including CSRD reporting requirements and the Science Based Targets initiative's Corporate Net-Zero Standard v2.0, both of which increasingly require companies to address residual emissions with durable removal rather than relying solely on avoidance or reduction measures.

 

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What the Verification Structure Signals About Credibility

 

Before signing, Carbonsate's project passed Senken's Sustainability Integrity Index, a proprietary review the company says fewer than 5 percent of carbon credit projects clear, layered on top of the project's existing independent verification under the Puro.earth standard and continuous monitoring through Carbonsate's own reporting system. That combination of independent third-party certification plus a buyer-side integrity screening process reflects the kind of layered verification increasingly expected in the durable carbon removal segment specifically, given how the broader carbon credit market's credibility has been affected by well-documented cases of overstated or unverifiable claims in less rigorously verified categories.

This agreement marks Senken's third multi-year supply commitment of 2026, following an earlier offtake for the aviation industry spanning direct air capture, industrial biochar and regenerative agriculture, indicating a company strategy of securing diversified permanent removal capacity across multiple technology types rather than concentrating exclusively on any single removal method. Whether Carbonsate's project scales beyond its current early-stage output, roughly 10,000 credits expected in 2026, toward the more than 100,000 tonnes per year capacity both companies say is achievable within the next few years, and whether that expansion proceeds on the timeline needed to fulfil the full 50,000-tonne commitment through 2028, will determine how significant this deal proves for closing the gap between corporate demand and available permanent removal supply.