Three of Ravensdown’s seven lime quarries use coal to fuel the drying process, and drying limestone produced 3,889 tonnes of greenhouse gas emissions in 2019, 25% of Ravensdown’s core annual emissions.
The team at Dipton Lime has succeeded in producing lime while burning wood in place of coal, resulting in a much lower carbon product. Now work resumes to refine the process to produce lime to the highest quality standards, and at the lowest cost. The investigation into alternative fuels for drying lime has been in-depth and is ongoing as part of the carbon reduction roadmap that the Operations team has developed. Last year we undertook a large-scale scoping study to identify alternatives to coal for drying lime. Woody biomass was identified as one of the preferred options and so a technical feasibility study followed. The recent trials at Dipton proved that alternatives exist for processing lime sustainably.
Early results reflect substantial efficiencies gained by selective mining, eliminating drying in favourable conditions and investment in improved infrastructure for screening, monitoring moisture and conserving heat. Continued investment and trials are underway on various energy options and improved production processes for further reductions. In 2019, the lime business reduced reliance on coal by 33% representing a saving of 1,378 tonnes of CO2, and 9% of Ravensdown’s total direct emissions.
Following these reduction measures, several options for full replacement of coal are being studied and several retired areas of the quarries, particularly those with erosion-prone land or ecological value, have been put forward for a native forestry planting programme, designed to sequester carbon while offering ecological, biodiversity and aesthetic benefits to the local areas.