Burying the Problem: Wood Vaulting as a Climate Solution
The fight against climate change requires a multi-pronged approach, and one increasingly promising strategy involves strategically burying the very fuel that feeds our warming planet: wood. Wood vaulting, a nascent carbon dioxide removal (CDR) technology, proposes a simple yet potentially impactful solution: burying woody debris and small trees deep underground to prevent them from decomposing and releasing their stored carbon into the atmosphere.
Across vast swaths of the western U.S., forests are grappling with the consequences of decades of fire suppression. Thick, dense undergrowth, choked with dead and downed trees, has created a tinderbox waiting to ignite. The U.S. Forest Service’s wildfire crisis strategy calls for thinning up to 50 million acres of land by 2032, generating a massive amount of biomass – potentially 2.2 billion metric tons of carbon dioxide equivalent – that must be managed responsibly.
Wood vaulting offers a potential solution to this dilemma. Instead of sending this woody material to a pulp mill or leaving it to rot and release its stored carbon, wood vaulting aims to lock it away underground for centuries. This emerging technique holds immense potential, particularly in regions plagued by forest overgrowth and wildfire risk.
How does wood vaulting work? It’s deceptively simple: a large excavator digs a hole 15 to 25 feet deep, and layers of woody biomass are carefully stacked inside. Gaps between the logs are filled with dirt, and the vault is capped with topsoil, effectively burying the wood deep underground.
The key to its success lies in creating a stable environment where decomposition is minimized. This means selecting appropriate locations with low water content and minimal oxygen intrusion, preferably in clay or silty soils away from groundwater. Monitoring systems are also essential to track oxygen, moisture, and methane levels over time, ensuring the vault remains intact for decades, even centuries.
While wood vaulting holds great promise, there are potential downsides to consider. Digging such deep trenches can disturb soil, potentially impacting habitats and nutrient cycling. Additionally, there are concerns that wood vaulting could unintentionally encourage increased logging. To mitigate these risks, companies are targeting specific types of biomass, including:
- Leftover biomass from wildfire risk reduction treatments: This ensures that wood vaulting complements, rather than incentivizes, existing forest management practices.
- Trees already burned or removed from urban areas: Wood already rendered unsafe for other uses presents a valuable opportunity for carbon sequestration.
Companies involved in wood vaulting prioritize transparency and responsible sourcing. Guidelines like those from Stripe Inc.’s Frontier fund, a leading purchaser of carbon dioxide removal credits, actively discourage the use of newly-harvested wood, emphasizing that wood vaults should focus on existing resources.
The science behind wood vaulting’s long-term effectiveness is still developing. While initial estimates suggest that wood vaults could effectively store carbon for hundreds, even thousands of years, further research is critical to confirm its durability. However, historical evidence provides a glimmer of hope. A 3,000-year-old red cedar log unearthed during excavation at a wood vault site in Canada revealed that only 5% of its original carbon had been lost.
Wood vaulting also holds a distinct advantage when compared to other established carbon sequestration methods. Its carbon yield is significantly higher than that of biochar, a charcoal-like soil amendment, which retains about 30% of the original biomass carbon, while wood vaulting is estimated to store over 90%. Furthermore, wood vaulting is relatively inexpensive compared to other approaches, such as direct air capture, estimated to cost between $600 and $1,000 per metric ton of CO2. The costs associated with wood vaulting are primarily driven by transportation, making proximity to source material a crucial factor in project viability.
Several companies are actively developing wood vaulting projects across the United States. The Carbon Lockdown Project, founded by Ning Zeng, has established research sites in Canada and Maryland, while Mast Reforestation, focused on reforestation after wildfires, plans to construct a large-scale wood vault in Montana, in partnership with Zeng’s team. Kodama Systems is pursuing a project in Nevada, aiming to store 1,000 metric tons of CO2 equivalent.
While the concept of wood vaulting is gaining traction, there are several hurdles to overcome before it can be implemented on a large scale. More scientific research is needed to verify the long-term carbon storage capabilities of wood vaults. Securing funding for pilot projects and scaling up operations, as well as creating a robust market for carbon dioxide removal credits, are also crucial.
Ultimately, the success of wood vaulting hinges on collaboration between the private sector and government agencies. While the Forest Service is a potential partner in the future, its notoriously slow pace of adopting new technologies means that public-private partnerships are still in their early stages.
Despite the challenges, wood vaulting presents a promising opportunity to address the dual concerns of forest overgrowth and climate change. By utilizing existing biomass, reducing wildfire risk, and effectively storing carbon underground, this simple yet innovative approach could play a significant role in mitigating the effects of a warming planet.
Will wood vaulting become a key tool in our fight against climate change? Only time will tell. But the potential is clear – burying the problem could be the solution we’ve been searching for.
