Cement – The Covert Climate Criminal

Think of the major carbon dioxide producing industries around the globe and start then to name some of the methods that you are aware of that are helping that industry reduce its carbon footprint. It’s highly unlikely that you will have named “cement” as one of those major CO2 producing industries despite that fact that globally, cement production accounts for three to four times the amount of CO2 in our atmosphere annually by the aviation sector. 

The Paris Climate Accord of 2015 has proven to be an effective catalyst for mobilising nations across the globe to respond to the climate emergency, and force them to make clear their commitment to limiting global temperature rise to 1.5° centigrade. Each participating nation published its roadmap for decarbonisation in the form of Nationally Determined Contributions (NDC’s) which focus that nations efforts on making the biggest and most attainable reduction in the various sectors of its own economy. Sectors which received the most attention across all countries include; transport (including aviation), housing and power generation. While manufacturing was another of those categories, the cement industry remained free from especial focus despite having a huge carbon footprint, three to four times the size of the global aviation industry.

As a global society, we marvel at our construction expertise, admiring the scale, height and complexity of structures that we are capable of erecting. Skyscrapers, airports, roads, bridges and the like demonstrate the prowess with which we are able to fashion raw materials from the earth into the facilities we feel we need to lead our lives through the centuries. Virtually all of these monuments to our capabilities utalise concrete, which in turn is derived from cement. As our society becomes more and more aware of the measures it needs to take to combat climate change, most people will not link the construction of new buildings, particularly in inner city locations, with climate damage. Many might think that our new buildings, significantly more efficient to run than those which they replace, are likely to make a contribution to energy reductions. Those who are environmentally conscious are most likely to consider that the eradication of petrol and diesel vehicles and perhaps the curtailment of unnecessary air travel should be the primary focus of our efforts to meet the targets set out in the Paris Climate Accord. Few, if any, will be aware that the production of cement, the primary ingredient in the production of concrete is a massive contributor to CO2 levels in our atmosphere, and without a broader appreciation of this fact, lasting damage to our planet will continue as nations continue to build new structures, and readily discard older buildings. Additionally, while society remains blissfully unaware of the scale of the impact of cement production on the environment, little or no pressure will be applied to the global cement manufacturing sector to change the way in which it manufacturers this product which our dependency on is likely to last for some centuries yet.

To understand why cement is such a significant CO2 producer, we need to examine how cement is manufactured. The process of making cement starts with the base resources which are most commonly limestone and clay which are crushed and mixed with other materials such as iron ore or ash. This mixture is then fed into huge rotating cylindrical kilns which are heated to temperature in excess of 1,400° centigrade by hot air being blasted through one end of the kiln. This causes a process called ‘calcination’ which splits the materials into calcium oxide and CO2 which is released into the atmosphere as a waste gas. The remaining material emerges from the hot kiln as small grey balls known as clinker which is cooled, ground and mixed with limestone and gypsum, at which point we know it as cement. The vast majority (90%) of the CO2 produced in the manufacture of cement lays in the clinker manufacturing process with quarrying, processing materials and cooling accounting for the remainder.

The United Nations Climate Change Conference which we know as COP has been debating the impact of cement on our climate for several years. The 26th annual conference, known as COP26 will now take place in Glasgow in November 2021 following a one year delay due to the Coronavirus. At COP24 in Poland in 2018, Cement Industry leaders discussed ways in which the requirements of the Paris Agreement on climate change could be met, agreeing that annual emissions from cement will need to fall by at least 16% by 2030.

However, emerging economies such as China and India are going through a huge phase of infrastructure building which is fuelling demand for cement and concrete in their countries. Therefore, cement producers are looking for ways in which cement can be produced in a more environmentally friendly way, while other ideas include; carbon capture, clinker substitutes, alternative fuels for the process and something known as novel cements.

Novel cements, also known as low-carbon cements may be a real solution. One example is being pioneered by North Carolina company BioMason which uses a technique whereby sands are placed in moulds and injected with microorganisms which solidify the sand in a process similar to the way that coral is created. The system has been evolved to take only four days and the process involves no fossil fuels. However, construction as an industry is notoriously slow to adopt new technologies, especially around its most favoured solutions. Therefore, these products are going to require significant and widespread government support and encouragement in order to wean the industry off its dependency on carbon-heavy concrete.

Other solutions are available that merit consideration. Our propensity to demolish and rebuild structures in ever shorter time-cycles must be examined. The re-use and re-purposing of existing buildings is an extremely important option in terms of our attempts to reduce CO2 in construction as a whole, which equally has a lower impact on other environmental aspects such as landfill. Low and some medium rise buildings, particularly housing should be constructed of more sustainable materials such a timber. While cement and concrete will almost certainly play a part in the construction sector for many decades to come, proactive choices by designers to avoid cementitious materials could greatly reduce our dependency while other novel cement options are given time to develop a foothold in the sector.

It would be fair to assume that most people would be sceptical of our ability to reduce our dependency on cement in the short term given the fact that nations like China and India are presently the biggest consumers of the material. However, one might be surprised to learn that an Indian cement manufacturer is leading the way in terms of reducing the CO2 associated with the production of its cement. Dalmia Cement as a group has implemented a programme of low carbon fuels, green materials and cleaner fuels across all of its 14 cement plants in India. As a result its plants produce on average 578kg of carbon dioxide per one tonne of cement against a global benchmark of 900kg, while at its most efficient Eastern Operations plant, Dalmia has reduced this to as low as 342kg.

Cement and concrete is without doubt among of the most useful materials available to us on the planet, however the vast majority of us do not associate the huge buildings we see being constructed with the huge amount of damage that arises from our dependency on cement. A greater global public awareness of the damage that current cement production methods is doing to the environment is needed in order to redirect architects and engineers away from the material and to encourage cement producers such as Dalmia to amend their processes in order to lessen that environmental damage that the residual cement market does to our planet.