Cement is arguably the most important material to have shaped human civilisation and the global environment. Cement is a material used in many construction applications and products, originally invented by the Romans mixing volcanic ash and lime. These days it is manufactured in large energy intensive kilns and when combined with sand and gravel it is used to make concrete. Concrete is the most widely used material in existence, it is only behind water as the most consumed material.
According to Chatham House, the Cement industry contributes 8% to the worlds CO2 emissions. The main source of the emissions comes from the production of clinker made within the cement kiln, a conventional kiln operates at temperatures above 1,400oC, thus demanding a large amount on energy for production.
Approximately, 1 tonne of (Portland composition) cement using conventional practices generates 900 kgCO2. Emissions are generated both by burning fuel and the calcination process where CO2 is liberated from lime to make calcium oxide. Process emissions account for 50% of all industry CO2 emissions, thermal energy accounts for 40% which dwarfs the remaining emissions from quarrying, grinding, cooling, mixing and transport related emissions.
The economic recession in 2011 had a significant impact on global cement production, the past three years had showed signs of recovery. In 2017 the worlds cement production was estimated to be 4.1billion tonnes, crudely 3.7 billion tonnes of CO2 (assuming 100% Portland). This production comprised of China the worlds primary producer at 2.4 billion tonnes of cement, followed by India 280 million tonnes, USA at 88.5 million tonnes and the UK a mere 9.4 million tonnes (CEMBUREAU).
Prior to the COVID outbreak, the IEA CSI Cement Technology Roadmap predicts that global cement production was set to grow by 12‑23% by 2050, a significant rise in global CO2 emissions. The IEA states that from 2014 to 2017, the direct CO2 intensity of cement production increased 0.3% per year. So, in maintaining this course there is a global emissions problem, and a new direction is needed.
The industry has made improvements, such as fuel switching, improving thermal efficiencies and substitution of raw materials with cementitious by-products (e.g. granulated blast furnace slag and pulverised fuel ash from coal fired power stations). But for the industry to adequately decarbonise in line with sustainable development objectives and CO2 budgets, deeper cuts are desperately needed whilst simultaneously keeping the price of construction materials affordable. These challenges cover the entire supply chain, requiring different management approaches, different standards and specifications, new materials, new innovations in chemistry and thermal efficiency, and new technologies.
There are additional supply chain challenges for developed economies. The UK cement’s carbon intensity has historically benefited from the relative abundance and ease of access to by-product materials used in lime substitution. However, these sources have become scarce, due to global coal fired power station closures (a good thing) and steel making relocating to emerging economies (carbon leakage – not so good). These pressures have resulted in short term strategies for importation, and whilst the carbon emissions associated from transporting materials from further afield are still offset by removing lime from process emissions, there is now a strong global competition for securing by-products. A more sustainable strategy is required for an industry contributing £117 billion to the UK economy and supports 2.3 million people.
Like many global economies who have relied upon coal as a source of electricity, the UK does boast large stockpiles of pulverised fuel ash (PFA) which have been historically landfilled due to supply/demand imbalances. The UK Ash Quality Association has conservatively estimated there to be 40 million in reserves across the UK, and The American Coal Ash Association puts US resource estimates as 2.5 billion tons, however not all will be viable for recovery.
The rates of substitution in cement vary due to end application requirements and the quality of the ash which may be used, a substitution rate of 30% saves approximately 273kg/CO2 per tonne of cement produced. These savings are significant and will be useful tool for an industry which needs to significantly reduce its global emissions, whilst no single solution holds the key to decarbonisation, short term positive steps are needed now more than ever.
A solution which improves the viability of recovered minerals and other substitutes in the cementitious supply chain may be difficult, but it is not insurmountable as technology is emerging; for the UK economy to recover speedily the construction industry will need all its tools to hand.
In October 2017 the UK Government in conjunction with the Mineral Processing Association published its own sector roadmap for decarbonisation and improving efficiency (Link).
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National Innovation Support
The following R&D and innovation programmes are running to support UK industry transition and decarbonise.
Industrial Strategy Fund Challenge: Industrial Decarbonisation
- This challenge aims to accelerate the cost-effective decarbonisation of industry by developing and deploying low-carbon technologies. It also aims to enable the deployment of infrastructure at scale by the mid-2020s.
- The Industrial Decarbonisation programme is funded by £170 million from the Industrial Strategy Challenge Fund which is expected to be matched by funding of up to £261 million from industry.
Industrial Energy Transformation Fund
- UK Government have set targets to help businesses improve their energy efficiency by at least 20% by 2030, but it is acknowledged further support is needed.
- The £315 million Industrial Energy Transformation Fund (IETF) will support businesses with high energy to use, mature energy efficiency technologies, Deploy deep decarbonisation technologies, Feasibility and Front-End Engineering and Design (FEED) studies and capacity for resource support.
Industrial Heat Recovery Support Programme
- The Industrial Heat Recovery Support (IHRS) programme is designed to encourage and support investment in heat recovery technologies.
- Grant funding available from a total pot of £18 million (2020 – 2022), feasibility studies, preliminary engineering, and detailed design studies.