As a key input into concrete, the most widely used construction material in the world, cement is a major contributor to climate change . The chemical and thermal combustion processes involved in the production of cement are a large source of carbon dioxide (CO2) emissions. Each year, more than 4 billion tonnes of cement are produced, accounting for around 8 per cent of global CO2 emissions.
Per Middle East Magazine and according to Citi’s MENA Projects Tracker, $2.5 trillion of projects are under development or actually under construction across the MENA region. Of these, 90% are in the Gulf and 60% are in just two countries: the UAE and Saudi Arabia. By sector, just over $1 trillion of this total is being invested in MENA real estate projects and $812bn in infrastructural schemes. The scale of this investment can be seen in comparison with the $376bn that is being spent on the lynchpin of the regional economy: oil and gas. The report’s author, Farek Soussa, commented: “There is a heavy bias in the UAE towards real estate projects, while infrastructure projects dominate in Qatar. The oil and gas sector is of greatest significance in Algeria, while Jordan is spending most on power and water.” Cement is of course the main ingredient that is an absolute must in any building and / or infrastructure development.
A Chatham House report on Making Concrete Change: Innovation in Low-carbon Cement and Concrete by Johanna Lehne, Research Associate, Energy, Environment and Resources and Felix Preston, Senior Research, Fellow and Deputy Research Director, Energy, Environment is excerpted here below starting with its Executive Summary first few words.
No silver bullet
Shifting to a Paris-compliant pathway, with net-zero CO2 emissions by around 2050,7 will require going further and moving faster on all available solutions, as well as making sure that the next generation of innovative technology options is ready as soon as possible.
To illustrate the scale of this challenge, Figure 1 shows the decarbonization pathway set out by the IEA and CSI’s 2018 Technology Roadmap.8 This scenario shows action on four mitigation levers – energy efficiency, fuel switching, clinker substitution and innovative technologies (including CCS) – to achieve CO2 reductions consistent with at least a 50 per cent chance of limiting the average global temperature increase to 2°C above pre-industrial levels by 2100.
Figure 1: Towards a Paris-compatible pathway
Source: Authors’ analysis of scenario set out in International Energy Agency and Cement Sustainability Initiative (2018), Technology Roadmap: Low-Carbon Transition in the Cement Industry, Paris: International Energy Agency, https://www.wbcsdcement.org/index.php/key-issues/climate-protection/technology-roadmap (accessed 24 Apr. 2018). The B2DS is based on data in International Energy Agency (2017), Energy Technology Perspectives 2017.
Note: RTS stands for ‘reference technology scenario’, 2DS stands for ‘2°C Scenario’ and B2DS stands for ‘Beyond 2°C Scenario’. For descriptions of each model, refer to the original source. The ETP B2DS and roadmap models are not directly comparable as they are based on slightly different assumptions as to future demand for cement but they are shown together here as an indicative comparison.
As recognized in the 2018 roadmap, there is a considerable gap between this scenario and a scenario consistent with countries’ more ambitious aspirations in the Paris Agreement of limiting the temperature increase even further, towards 1.5°C. The IEA’s Beyond 2°C Scenario (B2DS) indicated earlier is only an illustration of the challenge such an emissions reduction would represent in relation to current industry ambitions.
Shifting towards B2DS will require more ambition across each of these levers, particularly in the short term:
· Although many of the relatively straightforward gains have already been made, there is still scope for improvement in energy efficiency. Europe and the US now lag behind India and China on energy efficiency, due to the continuing use of older equipment, and will need to at least close this gap in the next decade if they are to meet industry targets. The key challenges will be the capital investment required and the fact that action on other levers such as alternative fuels and CCS may slow progress on energy efficiency.
· Shifting away from the use of fossil fuels in cement production will also be key. China and India, in particular, have significant potential to switch to sustainable lower-carbon fuels. In Europe, cement plants have been shown to run on 90 per cent non-fossil fuels. A key challenge will be to ensure the availability of biomass from truly sustainable sources. Currently, the sector relies largely on waste-derived biomass; however, shifting towards a majority share of alternative fuels may eventually prompt the sector to turn to wood pellets.
· Clinker substitution involves replacing a share of the clinker content in cement with other materials. This could play a greater role than currently anticipated. Achieving an average global clinker ratio of 0.60 by 2050, as set out by the 2018 Technology Roadmap, has the potential to mitigate almost 0.2 gigatonnes (GT) of CO2 in 2050.9 The share of clinker needed can be reduced even further in individual applications, with the potential to lower the CO2 emissions of those applications by as much as 70–90 per cent. At the very ambitious end of the scale, if 70 per cent replacement was achieved on a global scale, this could represent almost 1.5 GT of CO2emissions saved in 2050.10 Clinker substitution is not only a very effective solution, but also one that can be deployed cheaply today, as it does not generally require investments in new equipment or changes in fuel sources. It is, therefore, especially important to scale up clinker substitution in the near term while more radical options, such as the introduction of novel and carbon-negative cements, are still under development. The greatest constraints are the uncertain availability of clinker substitute materials and the lack of customer demand for low-clinker cements.
· Many experts are understandably sceptical about the potential to rapidly scale up CCS. Although other technologies are included in this lever, as presented in Figure 1, in practice hopes are currently pinned on CCS. This is reflected in both the 2018 roadmap and other major modelling exercises today. Even if hopes for CCS prove optimistic, carbon-capture technology could still prove critical in moving to B2DS. Moreover, CCS could complement the development of some novel concretes, which rely on a source of pure captured CO2 for carbonation curing. One of the key challenges facing CCS is the cost of the technology versus that of other levers.
However, it will be impossible to even get close to B2DS without also achieving radical changes in cement consumption and breakthroughs in the development of novel cements:
· Most cement emissions scenarios depend on projections of consumption that deserve far greater scrutiny. Concrete demand can be reduced, sometimes by more than 50 per cent, by taking a new approach to design, using higher-quality concretes, substituting concrete for other materials, improving the efficiency with which it is used on construction sites, and increasing the share of concrete that is reused and recycled. Deploying an array of such demand-side approaches in key growth markets such as China, India and African countries will be essential if the sector is to reach net-zero emissions. Action on material efficiency will, however, depend on the cooperation and motivation of a host of actors beyond the cement sector.
· Moving towards net-zero emissions for all new construction will require a rapid scale-up in the deployment of novel cements. Some can achieve emissions reductions of more than 90 per cent. Others can sequester carbon, theoretically capturing more carbon than is emitted in their production, rendering them carbon-negative. So far, however, the majority of these products have failed to achieve commercial viability. Achieving breakthroughs in this area will require concerted investment in research and large-scale demonstration projects, as well as education and training of consumers to build the market for novel products.
Even with ambitious projections across all mitigation levers to meet the B2DS, more than o.8 GT of CO2 would still be emitted in 2050. These ‘residual emissions’ would need to be offset by other means. Achieving zero CO2 emissions, therefore, needs to remain an objective beyond 2050. Failure to do so will imply a greater reliance on negative-emissions technologies that have so far failed to scale.
