Cement production is an energyintensive process. We have modernized our plants and improved our energy efficiency to reduce the carbon intensity of our products and lower our production costs, driving energy consumption per ton of clinker from 4,623 megajoules in 1990 to 3,526 megajoules in 2019, making us among the most efficient in the sector.
We also reduce the carbon intensity of our cement by replacing fossil fuels with pretreated waste and low-carbon fuels to operate our cement kilns. We currently source 20% of our energy from alternative fuels, low carbon fuels and biomass. In some of our operations, we’ve met over 90% of our energy requirements with alternative fuels. These alternative energy sources not only help reduce our CO2 emissions – they also divert waste from incineration or landfill.
Our primary carbon reduction lever is to lower the clinker-to-cement ratio. It is during the production of clinker, the main component of cement, when most CO2 emissions associated with cement occur. The majority of these emissions are unavoidable, as they result from the chemical reaction that occurs when the raw material (limestone) calcinates into clinker in the kiln. This decarbonation process is our largest source of CO2 emissions, accounting for 65% of our total scope 1 emissions in cement production. Replacing the clinker in our final cement products with alternative mineral components (a significant portion of which comes from waste or byproducts from other industries) reduces the carbon intensity. Our products currently use an average of 29% of constituents to replace clinker, resulting in one of the lowest levels of clinker content (or ‘clinker factor’) in the sector.
In 2019, we continued to expand our renewable energy portfolio, adding close to 250 MW equivalent of clean power to our global electricity mix. We also optimized our power-producing assets (for example by installing waste heat recovery units) across our production plant portfolio. We currently operate 5 waste heat recovery units in 4 countries and plan to increase this to 12 units by 2021, with a larger pipeline to be implemented in phases. We are also taking advantage of opportunities to generate renewable energy on our land by installing wind turbines and solar panel farms. In October 2019, for example, three wind turbines built on our site in Paulding, OH (US) began delivering 12 million Gigawatt hours per year to the plant, eliminating the emission of at least 9,000 tons of CO2 annually. In India Ambuja Cement has recently commissioned an onsite solar plant at its Rabriyawas plant. The plant will have a capacity of 11.5 Gigawatt hours per year and will avoid 8,900 tons of CO2 emissions per year.
We have made significant investments in low-carbon solutions, much of it through our Innovation Center in Lyon, France. Today we have a broad portfolio of low-carbon projects including low-carbon clinker, cement, concrete, and binders. We take it as our responsibility as a global leader in building materials to pave the way to low-carbon construction. For more information on our innovation program and products.
Apart from our ongoing activities to reduce CO2 emissions, reducing CO2 emissions from cement production to zero will require carbon capture and usage or storage (CCUS). The IEA Roadmap for the cement sector projects CCUS to begin at scale from 2030 onwards. LafargeHolcim is currently working with a number of partners on five projects in four countries, and plans to increase that number in the coming years. The potential carbon capture capacity from these projects is approximately 2 million tons of CO2 per year.
