Biochar is a form of charcoal created by heating organic material, known as biomass, in an environment without oxygen at temperatures of 400°C or higher. This process, called pyrolysis, produces energy-rich gases and liquids as well as a solid product—biochar.

When this solid product is designed to sequester carbon, whether in soil or in other applications such as construction materials, it is referred to as biochar. By adjusting the conditions during pyrolysis, the properties of this material can be tailored. Generally, higher pyrolysis temperatures result in less biochar but with a higher content of stable carbon.

This stable carbon in biochar can remain stored for centuries, making biochar a significant tool in combating climate change. While most biochar is not a fertiliser in itself, it has been shown to improve soil structure by acting as a porous sponge that retains water and nutrients, thereby enhancing the effectiveness of existing soil amendments.

Beyond soil improvement, biochar has a range of alternative applications. It can be used in afforestation efforts to enhance soil conditions for tree planting, integrated into construction materials like concrete and asphalt to improve durability and carbon storage, and employed in environmental management to filter contaminants from water and air. In the built environment, biochar can also be used as an additive in green building materials to enhance insulation properties and reduce the carbon footprint of construction projects. These diverse uses underscore biochar's versatility and potential in various sectors.

Biochar can be produced from almost any dry organic material, including waste products. This makes biochar production a key component in the circular economy and sustainable agriculture, offering an opportunity to recycle organic waste, enhance soil health, and sequester carbon, contributing to long-term environmental and economic sustainability.

Historical Pedigree

Biochar, in various forms including plant and animal char, has been utilised for soil enhancement for thousands of years. The most compelling evidence of its long-term benefits comes from the Terra Preta soils in the Amazon Basin. These "dark earth" soils, created by indigenous peoples through the addition of char and organic waste, are renowned for their extraordinary fertility and high levels of stable carbon. Remarkably, these soils remain rich and productive even after thousands of years, serving as a testament to the enduring benefits of biochar.

In addition to the Amazon, historical use of char as a soil amendment has been documented in various regions of the world. In northern Europe, particularly in the Netherlands, Northwest Germany, and Belgium, char was traditionally added to soils to improve their quality. Similarly, biochar has a long history of use in Japan, where it is still applied today to enhance soil fertility. In West Africa, char remains an integral part of traditional farming practices, demonstrating its continued relevance in modern agriculture.

Linking the Past to the Present

These historical practices offer valuable insights for addressing modern-day climate change mitigation and adaptation challenges. The ancient use of biochar not only improved soil health but also contributed to long-term carbon storage—a principle that is at the heart of current climate strategies. As we confront the urgent need to reduce greenhouse gas emissions and enhance carbon sequestration, the enduring success of biochar in historical contexts underscores its potential as a sustainable solution today.

Learning from these traditional practices, modern biochar systems can be designed to mitigate climate change by locking away carbon in soils, improving soil fertility, and enhancing agricultural resilience. By integrating these ancient techniques with contemporary technologies, we can create sustainable land management practices that address the pressing environmental challenges of our time, proving that lessons from our past can indeed guide us towards a more sustainable future.