Slag is the molten runoff created during steel production in a traditional blast furnace. It has emerged as a promising alternative to cement for creating concrete, the most abundant human-made material on Earth. However, the supply chain for this runoff is facing challenges as the steel industry transitions towards greener production methods.
Steel producers in the U.S. and Europe are increasingly adopting electric arc furnaces (EAF) which are more efficient, smaller, and powered by electricity rather than coal. Cocoon is a startup that believes in the possibility of combining greener steel production with the creation of concrete slag.
Despite concerns surrounding concrete production, the demand for it continues to rise. Cement constitutes only 10-15% of a concrete mix but contributes to around 90% of its emissions. This has led the industry to seek eco-friendly alternatives. Cocoon is developing “e-slag,” a byproduct of energy-efficient steel production that can be used as a cement substitute.
Eliot Brooks, the cofounder and CEO of Cocoon, explains, “The challenge with steel slag is its high iron content, which limits its reactivity as a cementitious material. We have developed a two-step process to address this challenge and enhance its cementitious properties.”
Cocoon’s technology, still in the testing phase, aims to fit seamlessly into existing steel production processes. Their innovative system uses a shipping container to collect and process the molten material, providing a more efficient solution compared to traditional methods.
The company recently secured a $5.4 million pre-seed funding round with investments from Wireframe Ventures, Untitled, Gigascale Capital, and SOSV. Cocoon is using this funding to establish an R&D facility in London and conduct initial tests at steel plants in the UK and the U.S. The goal is to integrate their technology into a pilot plant by late 2025.
