FAQ

What’s special about the Black Sea?

The Black Sea is already one of the largest natural carbon sinks in the world. The rivers around it deposit megatons of carbon every year, and in the anoxic bottom, the Black Sea preserves organic carbon for thousands of years. Its volume is big enough to contain all the CO₂ humanity needs to remove, and its special chemistry (no oxygen, high sulfide) ensures long-term preservation and environmental safety. Lastly, the Black Sea is also located in the middle of Europe’s bread basket, providing large quantities of residual biomass within reach.

Why are anoxic water basins good for carbon storage?

An anoxic water basin is an aquatic environment where there’s no dissolved oxygen. In the absence of oxygen, most aquatic organisms cannot survive. The only organisms that populate the anoxic part of the Black Sea are microorganisms, which can rely on molecules other than oxygen to metabolize. These microorganisms live at a much “slower pace” and they are limited in the types of organic matter they can consume. This is why anoxic water basins naturally preserve organic matter, aka biomass.

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What is biomass?

Biomass is a broad term describing all organic materials, from trees, through food, to food waste.

Is the Black Sea the only place in the world fit for anoxic biomass storage?

No. There are lakes that lack oxygen, as well as deep sea basins, or craters at the bottom of larger seas, which also lack oxygen. Having said that, the Black Sea is by far the largest anoxic basin in the world, which happens to be adjacent to an abundance of agriculture and forestry.

What types of biomass does Rewind use?

Rewind focuses on clean plants that have already been cut down for other uses, and are not utilized in agriculture or energy sectors. Usually, these residual plants are burnt or left to decompose in the field. Such sources of organic matter include forestry residue, orchard trimmings, and other agricultural crop residues.

Is the biomass sustainably sourced?

Our commitment to sustainability is at the forefront of our biomass sourcing strategy. We source biomass only from suppliers who adhere to stringent environmental standards. This includes ensuring that biomass comes from renewable resources, such as agricultural residues or sustainably managed forests. Our suppliers must demonstrate compliance with local and international environmental regulations, including maintaining biodiversity and preventing deforestation. Additionally, we prioritize using waste biomass, which not only diverts biomass from being burnt but also enhances the circularity of our operations. By continuously verify our sources and monitoring our supply chain, we ensure that our biomass is sustainably sourced, minimizing ecological impacts and supporting sustainable development goals.

Is it environmentally safe to store biomass at the bottom of the Black Sea?

Organic matter deposition and sequestration is a nature-based solution. The large rivers flow to the Black Sea, transporting millions of tons of terrestrial organic matter to the deep bottom of the Black Sea, where it is stored for thousands of years away from the atmosphere. Rewind enhances this natural process and is committed to measuring, monitoring, reporting, and verifying the ecological safety of the deposition of organic carbon.

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What environmental impacts need to be considered?

• Diverse Marine Ecosystems: The Black Sea's rich tapestry of life, from vibrant fish to microorganisms, is a top priority. Our biomass deposition strategy is fine-tuned to minimize disruption. We rapidly submerge the biomass through the upper oxygen-rich layers to minimize contact with the diverse marine life..
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• Microbial Dynamics in Depth: In the deeper, oxygen-deprived layers, our focus shifts to maintaining the balance of bacterial and archaeal communities. Through detailed sediment analysis, we monitor changes in microbial activity and composition.
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• Chemical Equilibrium in Waters: We're careful about potential shifts in chemical balances, like CO2 and methane emissions. Our strategy includes an environmental impact assessment, followed by a gradual biomass introduction. This phased approach allows us to monitor and adapt to maintain aquatic health.
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• Terrestrial Nutrient Preservation: Our approach integrates the value of biomass for soil health with rigorous MRV systems, ensuring balanced nutrient cycles and land integrity. We focus on regenerative agriculture and sustainable forestry, fostering a cycle of sustainable biomass use.

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What scale can biomass storage in the Black Sea achieve?

The Black Sea is surrounded by six countries with fertile land, forests, and agriculture, with hundreds of millions of tons of biomass residue every year. These conditions allow for an abundant supply of organic matter with low or no commercial value. We aim to tenfold our carbon removal every year, reaching a gigaton scale by 2030. In addition, the Black Sea contains 540,000 Gt of water. Rewind's models conservatively estimate that the Black Sea alone can store 300 GT of CO2, making 1 GT / year a drop in the ocean (literally) 😉.

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Will Rewind’s method stay environmentally safe even at a gigaton scale?

There's minimal biodiversity in the deeper parts of the Black Sea, so the potential for significant change or harm is quite limited.

Also, given the Black Sea's immense volume of about 540,000 gigatons of water, the addition of one gigaton is insignificant. For a comprehensive analysis, refer to the scientific paper "Biomass Storage in Anoxic Marine Basins: Initial Estimates of Geochemical Impacts and CO₂ Sequestration Capacity" by M. R. Raven et al.

What are the main benefits of biomass carbon removal and storage (BiCRS)?

The primary benefits of BiCRS include efficient and scalable carbon sequestration, reduced land and water usage compared to traditional methods, and the potential for long-term, stable carbon storage. Additionally, BiCRS can contribute to circular economy practices by utilizing waste biomass as a resource.

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Is there supporting scientific research for your method?

Several studies have examined the decomposition rate of terrestrial biomass on the seabed, along with studies of wooden shipwrecks preserved at the bottom of the Black Sea for over 2,000 years and how terrestrial biomass is deposited in sediments by rivers and preserved over geological time. Rewind's team not only bases their work on these studies but also actively engages in scientific experiments. Their collaboration with leading global scientific experts ensures that the methodology is robust and well-grounded in science.

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Is Rewind’s MRV (Monitoring, Reporting, and verification) based on measurements or statistical models?

Rewind employs direct measurements for processes like weighing the biomass and analyzing its chemical composition. In addition, the permanence of the sequestration is verified with real samples extracted during the lifetime of a storage site. Complementing the real-life measurements are predictive models for dispersion due to currents and for extrapolation.

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How much biomass is required to remove 1 ton of CO2?

In short: a 1:1 ratio, inclusive of factors such as supply chain emissions and long-term preservation.

On average, dry wood is about 50% carbon by weight. Therefore:
1 ton of dry wood = 0.5 ton of carbon atoms = 1.84 tons of CO2.
After taking into account supply chain emission, and guaranteed long-term preservation factor (66%), we are left with “1 ton of dry wood = 1 ton of CO₂”

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Doesn’t it require a lot of fuel to transport biomass to the Black Sea?

Not at all. Based on previous studies and our life cycle assessment calculation, the total transportation energy consumption of biomass to the bottom of the Black Sea is less than 10% of the carbon we fix.

Doesn’t carbon removal encourage continued emissions and delay solving the climate crisis?

While it's crucial to reduce emissions at the source, carbon removal is an essential complementary strategy. It addresses already emitted greenhouse gases and is a vital tool in our arsenal against climate change. Our approach is to work in tandem with emission reduction efforts, not to replace them.

How is storing plants in the sea removing carbon from the air?

One of nature’s ways to remove CO2 from the carbon cycle is by transporting plants through rivers and into the depths of the sea. Since the carbon in plants comes from CO2 in the air (via photosynthesis), plants that accumulate on the seabed form deep reservoirs of organic carbon. This is nature’s way of creating fossil fuels. Rewind mimics and accelerates this process by collecting agriculture & forestry residues and transporting them to the deep Black Sea, effectively removing CO2 for thousands of years.

Isn’t Rewind just reducing emissions from agriculture?

No. Since plants capture the CO₂ from the air, once it is released to the air it does not increase the concentration of CO₂. It is net-neutral. Emissions from agriculture come from livestock emissions (cows burping methane), from land use change (cutting down forests to grow crops), from plowing the soil (releasing carbon which was stored in the soil), and from over-fertilization (most commercial fertilizers are produced from fossil fuels).

Isn’t planting trees a simpler, better solution?

While planting trees is important for carbon absorption and ecological balance, it is not a standalone solution for climate change. Afforestation requires extensive land and has limitations, such as the eventual release of CO₂ when trees die. This is where Biomass Carbon Removal and Storage (BiCRS) complements nature-based solutions. BiCRS involves processing biomass for carbon capture and securely storing it, preventing its re-release into the atmosphere. This method offers a more scalable and permanent solution to carbon sequestration, effectively complementing tree planting by addressing the limitations of afforestation and providing a robust, long-term approach to managing atmospheric carbon levels.

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