Transformation pathway to a green lime offer

The Autoclaved Aerated Concrete (AAC) industry has announced an ambitious decarbonization roadmap to 2050 to keep its place as a reference product in the future market of building materials. AAC raw materials are contributing to a large share of the CO₂ footprint of AAC and need to be carefully assessed. Lime is today an essential raw material in the production of AAC and will remain so in the future as, unlike some other raw materials, it cannot be interchanged by a less carbon‐intensive alternative. Lime is essential in the formation of Tobermorite and provides the alkaline conditions required for the formation of the hydrogen bubbles structuring the mineral foam. Lime is produced by the calcination of limestone (CaCO₃) releasing carbon dioxide (CO₂). The CO₂ footprint of lime is considerable, and the production process is considered hard‐to‐abate. Today roughly two‐thirds of the CO₂ is inherent to the production process while only one‐third of the CO₂ is due to the required fuel. Lhoist has developed a Carbon Action 2030 plan with a range of low‐carbon and carbon‐neutral lime solutions. The approach is based on the principle of three pillars: Avoiding, Reducing, and Compensating with a pipeline of effective carbon reduction initiatives behind each pillar. The paper will provide a status update on the key projects in Belgium, France, and Germany. The transformation to low‐carbon lime has triggered projects in energy improvement, sustainable fuels, the usage of hydrogen, kiln electrification, oxyfuel kilns, carbon capture, and storage as well as CO₂ utilization. Once the CO₂ is captured during the production of lime, the carbonation of the AAC will lead to a carbon‐negative building material. Our roadmap will position Lhoist as a preferred partner for the AAC industry in the future. Our lime product portfolio ranging from Level|Blue™ to Level|Green™ will support the AAC industry to consolidate and develop its referential position in the building materials industry.