Senken and Carbonsate Sign Europe’s Largest Biomass Storage Carbon Removal Deal
Senken has signed a multi-year carbon removal offtake agreement with Berlin-based Carbonsate covering 50,000 tonnes of permanent carbon removal from biomass geological storage projects in Namibia between 2026 and 2028.
The agreement represents the largest biomass storage deal signed in Europe to date and the second-largest buyer commitment globally in the biomass geological storage category. It also represents the largest such commitment for a project operating in Africa.
Deliveries under the agreement are scheduled to begin in 2026. Senken said the commitment reflects growing demand for durable carbon removal as companies seek access to a limited supply of independently verified permanent removals to support their longer-term net-zero strategies.
The 50,000-tonne commitment is equivalent to approximately 4% of the estimated 1.5 million tonnes of permanent carbon removal delivered by the entire market to date, highlighting the still-limited scale of the permanent carbon removal sector.
The carbon removals will come from Carbonsate’s biomass storage projects in Namibia. The company uses waste wood as the carbon feedstock, placing the biomass inside engineered underground chambers designed to prevent combustion and decomposition. By keeping the carbon contained, the process aims to prevent the carbon stored in the biomass from returning to the atmosphere for centuries.
Unlike carbon removal approaches that require energy-intensive carbon capture processes, biomass storage relies on the physical isolation of carbon-rich waste biomass. Carbonsate says this can provide a permanent storage pathway at substantially lower cost than technologies such as direct air capture.
The project is independently verified under the Puro.earth standard, with Carbonsate using a proprietary monitoring, reporting and verification system to track the storage sites and the permanence of the removals.
Senken’s multi-year purchase agreement provides Carbonsate with contracted demand through 2028, giving the developer greater visibility as it expands its storage capacity in Namibia. For Senken, the agreement secures future access to a relatively scarce category of high-durability carbon removal for European buyers.
Senken CEO Adrian Wons said demand for permanent carbon removal is already exceeding available supply, with corporate net-zero commitments competing for a limited pool of verified removal capacity. He said the multi-year agreement is intended to provide European buyers with access to credible removal volumes at prices that can be planned for over several years.
Carbonsate Co-founder and CEO Johanna Broell said long-term buyer commitments provide project developers with the certainty required to build storage capacity ahead of future demand. The company expects the agreement to support the expansion of its Namibia operations and increase the supply of verified carbon removal available to the market.
The transaction comes as the carbon removal market moves toward longer-term purchasing agreements, with buyers increasingly seeking durable removal technologies that can provide measurable and independently verified atmospheric carbon reductions.
Senken provides carbon credit procurement and due-diligence services to European companies, using its Sustainability Integrity Index to assess projects across more than 600 data points. The company says its screening process rejects the majority of projects reviewed and provides buyers with documentation designed to support audit and corporate reporting requirements.
Carbonsate specialises in biomass storage, developing projects that permanently store waste wood in engineered underground chambers. Its Namibia projects are designed around long-duration carbon storage, supported by monitoring, reporting and verification systems and independent certification under the Puro.earth framework.
The 50,000-tonne agreement therefore represents a significant commercial commitment to biomass-based permanent carbon removal, while providing Carbonsate with a long-term buyer for its expanding African storage capacity and giving European customers access to a larger volume of independently verified durable carbon removals.
