Biochar: Capturing CO2 as insulation material

Researchers at the Swiss Federal Laboratories for Materials Science and Technology Empa, want to develop a novel type of insulating material from plant-based raw materials that can permanently bind CO2

A new research project by a team of scientists led by Jannis Wernery from Empa's Building Energy Materials and Components Lab is based on the idea of binding CO2 in newly developed insulation materials over the long term. The idea is to convert plant-based raw materials - ideally waste products from agriculture and forestry - into insulating materials for buildings. Most of the carbon bound in the biomass, can be permanently fixed by a special heat treatment. It remains bound in the resulting biochar throughout the life of the building - and even far beyond. Once the buildings have been deconstructed, this ‘biochar’ can be used in agriculture to increase soil fertility. Unlike other plant-based building materials, such as wood or cellulose insulation, which release the stored CO2 again when they rot or are utilized thermally.

However, according to Wernery, there is still a lot to do before the idea can be put into practice. For instance, it is important to ensure that all the ingredients of the novel insulation materials are suitable for later use as ‘fertilizer’. In addition, a marketable insulation material must also be able to compete with existing insulation products in terms of thermal insulation and must also be fire-resistant.

Still, Wernery is convinced that biochar-based insulation could significantly improve Switzerland's CO2 balance in the future. An initial analysis has shown that a realistic partial replacement of conventional insulating materials such as EPS or mineral wool with biochar could save a good half a million tons of CO2 equivalents annually.

This, by avoiding emissions during the production of the conventional materials, but also by long-term storage of CO2 in the biochar; which corresponds to more than one percent of Switzerland's total greenhouse gas emissions. According to Empa, the building sector is one of the most important drivers of global climate change. It is responsible for around 40 percent of global energy consumption, for 30 percent of greenhouse gas emissions and accounts for 36 percent of the waste generated in the EU.

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