Hemp vs. wood: which is the better carbon store?

The construction sector, a major contributor to greenhouse gas emissions, is increasingly seeking sustainable alternatives to traditional materials. Amid this shift, industrial hemp—a crop often overshadowed by its psychoactive relative, cannabis— becomes a promising candidate. A recent study by the nova-Institute, “Carbon Storage in Hemp and Wood Raw Materials for Construction Materials,” has provided compelling evidence for industrial hemp's potential as a carbon sink, positioning it alongside wood as a viable resource for the bioeconomy.

A comparison of carbon storage

The nova-Institute’s findings reveal that hemp can store between 9.5 and 11.4 tons of CO₂-equivalents per hectare annually, often surpassing common tree species like spruce or fir. With its rapid growth cycle—just five to six months compared to the decades needed for trees—hemp can sequester carbon far more quickly. This makes it an attractive option in the context of urgent climate targets.

However, when cultivation, harvesting, and processing emissions are factored in, hemp's net carbon storage capacity slightly lags behind certain tree species. This is largely due to the annual planting requirements and the emissions associated with fertilizers and processing. Yet, as Michael Carus, co-author of the study, points out, hemp's carbon storage could be even higher under optimised cultivation practices, such as increasing yields to match the upper range reported in some studies.

Agricultural benefits and challenges

Industrial hemp offers unique benefits for farmers and the environment. Hemp's ability to grow quickly and absorb significant amounts of carbon makes it an attractive option. Unlike forests, which take years to recover from damage, industrial hemp can be planted and harvested annually, which has a more immediate impact.

As a fast-growing annual plant, it can also adapt quickly to agricultural and market demands. Furthermore, it improves soil health by loosening compacted soils with its deep roots and sequestering carbon in the soil. Industrial hemp lends itself well to crop rotation, making it an excellent choice for sustainable farming systems.

However, challenges remain. Industrial hemp cultivation is sensitive to climatic conditions, such as spring droughts or overly wet harvest seasons. Additionally, its post-harvest processing and storage are logistically complex and costly, creating barriers for widespread adoption. In contrast, wood benefits from its established supply chains, longer storage life, and greater versatility in construction applications.

Hemp and EU carbon policies

One of the key obstacles for industrial hemp’s broader adoption as a carbon sink is its exclusion from the European Union’s Carbon Removal Certification Framework. Currently, wood is recognized under this framework, incentivizing its use in construction by allowing companies to trade carbon credits tied to its storage capacity. Despite its proven carbon storage capacity, hemp is currently excluded from the EU's carbon credit system.

The nova-Institute argues that hemp fits the EU’s criteria for carbon removal—quantification, additionality, long-term storage, and sustainability (QU.A.L.ITY). Its inclusion could diversify the bioeconomy and expand opportunities for farmers to participate in carbon markets.

The "Nutzhanfnetzwerk", an organisation that promotes industrial hemp, hopes that the nova-Institute's findings will encourage policy makers to rethink their approach. The inclusion of industrial hemp in the carbon credit system could create new incentives for industrial hemp cultivation, for example as part of broader carbon farming initiatives. It could also encourage the construction industry to use hemp-based materials. For example, hempcrete, a mixture of hemp hurds and lime, which offers a low-carbon alternative to conventional concrete. 

Incorporating industrial hemp into EU carbon markets could not only contribute to climate mitigation efforts but also provide financial stability for farmers. Industrial hemp’s dual-purpose nature—yielding both fiber and seeds—can offset cultivation costs, making it a profitable crop even without subsidies. With the additional potential for carbon credits, farmers could play a key role in the transition to a more sustainable construction sector.

The study also highlights the potential of industrial hemp in degraded agricultural landscapes and in areas where forests are suffering from climate stress. Germany's forests, which have long been considered important carbon sinks, are under increasing pressure from climate change. According to the latest National Forest Inventory, the country's forests have released 41.5 million tonnes of CO₂ since 2017, influenced by factors such as drought, pests and fires. As forests are no longer reliably sequestering carbon, the search for additional solutions has become urgent. Unlike traditional forestry, hemp does not require long-term land commitments and offers a flexible solution for regions where tree growth is declining due to drought, pest infestation or other climate impacts.

The Takeaway

The nova-Institute’s research paints a clear picture: industrial hemp can—and should—be part of Europe’s sustainable construction and carbon sequestration future. While challenges remain, its carbon storage capacity, agricultural versatility, and role in decarbonising the construction sector make a compelling case for its inclusion in EU climate policies. 

As forests continue to struggle under the weight of climate change, industrial hemp offers a resilient and efficient alternative that deserves the recognition—and action—of policy makers, such as recognising industrial hemp as a carbon sink in official frameworks, investing in hemp processing infrastructure and providing targeted subsidies. That could bring this versatile plant to the forefront of sustainable construction.