The development of new and more sustainable solutions is a core of Snøhetta’s work and the creation of a new type of carbon-neutral concrete Biocrete is a result of this. For Biocrete Snøhetta has teamed up with some of Norway's most experienced contractors, researchers, producers, and suppliers within the concrete and biochar industry. After several rounds of in-lab testing, the first carbon-negative precast concrete wall was cast in 2021. This milestone resulted in more rounds of testing and evaluations, and finally, in 2023 Biocrete concrete was poured for the very first time in a building project – a new barn near Bjørkelangen, just outside Oslo, Norway.
2 For the future
Concrete is the world’s most used building material and accounts for around 7 percent of the world's total CO2 emissions. Even with this unpleasant backdrop in mind, it’s hard to imagine that we will build less in years to come, and likewise, it’s hard to see we will find materials as versatile and long-lasting as concrete. This was the trigger in Snøhetta’s search for more environmentally friendly solutions allowing us to build in a way that doesn’t compromise the ability of future generations to meet their needs.
The idea of Biocrete comes from looking at the waste stream in the building industry and the question of how waste can become a sensible resource to utilize and lower our CO2 footprint. The answer was wood waste and concrete.
3 Wood and concrete
In total 1 million tons of surplus wood is thrown away every year in Norway, resulting in CO2 emissions through incineration or decomposition. By heating the wood to its pyrolyzed, a process giving biochar with more than 90 percent pure carbon, the excess heat is used for energy and heating. When biochar is mixed into concrete, it will compensate for its CO2 emission coming from production, transportation, and rebar use because the carbon will be locked in the concrete. In fact, one kilogram of pure carbon corresponds to 3.7-3.8 kilograms of CO2. When contained in concrete we save the atmosphere for the same amount. This is carbon storage, CCS.
The right recipes in the blend of biochar and concrete have been mixed through many series of testing, and the components can be mixed to meet specific needs and goals. The tests have been carried out at the Con-Forms factory in Orkanger and have proved successful for execution, properties of concrete, and have even achieved carbon-negativity.