CCUS & Construction Materials

This is from a speech I gave at the CCUS Forum Masterclass in Doha at the end of last month.

I’m the Director Environment & Sustainability for Surbana Jurong Design Team on a NEOM project, based in Riyadh, although normally resident on Australia’s Gold Coast. My sponsor for our project was SMEC, the Snowy Mountains Engineering Corporation, who are constructing the Snowy 2.0 pumped hydro project, one of the top 10 largest globally. Unfortunately, the tunnel boring machine (TBM) has had challenges that highlight the fact that the natural world and geology in particular is complicated and challenging.

I have been an earth scientist for 40-years, starting as a wellsite geologist with Baker Hughes. However, for the last 20-years my personal email and trademark has been CQuest, now GoCQuest (geosequestration) so you can understand my keen interest in the CCUS Conference.

My talk is about Construction Materials & CCUS.

Although modern construction designs are required to meet the highest standards in sustainability, such as the internationally recognized rating system ENVISION for Infrastructure and LEED for Buildings: their main focus is on building operations and not the significant source of greenhouse gas emissions (GHGE) within the construction materials themselves (Scope 3 or embodied carbon).

The outdated focus on ‘value’ was short-term cost and not longer-term sustainable value in a long-life cycle (LCA) where only 1% of buildings worldwide are demolished. Only a longer-term focus on sustainable outcomes, with longer payback periods, purchasing and investment priorities to match, can change this ‘value’ proposition. The construction materials themselves are cement, steel, ‘aggregate’, water, transport and fossil fuels, have the greatest global warming potential (GWP).

According to the IEA, since the millennium (2000), global demand for cement and steel has more than doubled. The buildings and construction sectors combined were responsible for 30% of total global energy consumption and 27% of total energy sector emissions. Since 2021, building and construction accounts for 35% of the world’s total energy.

All building products come from high emission energy intensive heavy industries, from mining abundant fossil resources such as iron ore, limestone, aggregate, gypsum, quartz, fuel, water; and processing and transportation. Of course, the same applies to the critical minerals needed for all renewable technologies only more challenging given their rarity, greater mining impacts and more polluting processing (LiO2).

Looking at processing minerals, in the case of good old iron ore, it requires a temperature of 2000oC for heating and the addition of pre-cooked bituminous coal (coke) to produce pig iron, and heating again to remove excess carbon with the addition of trace metals, to produce various steel grades.?Ordinary Portland Cement (OPC) requires heating limestone (clinker) to 1500oC with the addition of gypsum, and pozzolanic supplemental cementitious material (SCM), such as Kaolin (replacing shortages of high-quality steel slag and coal fly ash), this clinker process also requires 750oC. Glass requires heating pure quartz sand (75%), limestone (10%) and soda ash to 1500oC. Asphalt for sealing surfaces is made from oil distillation to produce fuel and petrochemical feedstock and because of its high asphaltene content requires 400oC at low pressure (0.1 bar) to produce asphalt. Lastly, gypsum is also produced for acoustic and fire retardation board totaling ~0.7Mkm2 requires heating to nearly 200oC to dehydrate it. All energy intensive heavy industries require energy dense fuels to heat and water to cool.

A hidden cost is also due to the production of all the broken rock and that is the use of explosives, a refined fertilizer (AN) product, mainly produced from methane. In the case of concrete aggregate, some 50 Bt are mined annually from 200,000+ quarries according to the Global Aggregates Information Network (GAIN). However, it doesn’t mention how much waste, usually fines too small to use, are produced to get the grades (psd) required. In the case of Aluminium production, for example, bauxite waste red-mud fines are dumped in ever expanding tailings dams that could be used. However, waste fines can now be used in reducing limestone by using basaltic type rocks as seeds and injecting CO2 to grow new carbonate nodules, produced by a California based company called Blue Pacific. In fact, using Ca-Mg-Fe rich rocks?can produce carbonates to capture CO2 in concrete, or the fractured rocks can be injected with CO2 in solution to lock-in carbonates such as the Carbfix process in Iceland or with supercritical CO2 (7.5MPa @ 25oC) in CCS mineralization.

The hidden cost that should outweigh all others, is the cost of producing sufficient cool clean water. Apart from poor water management practices worldwide, the greatest impact on water resources is climate change. The ultimate loss of recharging shallow water aquifers, tree (and biodiversity) removal causing soil salination and moisture and soil loss due to erosion, loss of mountain glacial ice, such as the Tibetan Plateau will have a devastating impact on the planets greatest concentration of people triggering further waves of climate refugees. Not an Arab Spring, but the loss of all springs/oasis’s, the source of life for all living things.

To reduce the embodied carbon, construction with lightweight and longer-life products, material use efficiency and modules (pre- cast, pre-fabricated or pre-formed), low carbon wood alternatives and reusability, and recycling waste from mining, all can contribute to the sustainable use of resources during their life cycle. Steel for example is the most recycled product on the planet and its reprocessing, using electric arc furnaces (EAF), produces half the GHGEs than raw pig iron. The eventual use of H2 reduction could replace the production of CO2 from using coke. Asphalt can be recycled into more asphalt. Kaolin (35%) with limestone (15%) can reduce CO2 in cement by 30% however cooking cheap readily available limestone will always produce CO2, therefore CCS is the only permanent solution to large point-source GHGEs.

Renewable energy sources to produce electricity will eventually replace fossil fuel. However, there is no substitute for water, the most undervalued and critical substance on the planet. As an example, when my home state had a long drought on a large desert island called Australia, they were looking at recycling wastewater, which is 99% water, recoverable and fit for irrigation, with nutrients already included, however the media hype was such that we couldn’t use human waste!

Desalination is a critical requirement in all countries, not just the Middle East, even if we have it on standby, but thermo and filtration (UF-RO) technologies still require high energy inputs. Again, much like carbon capture, amines may provide a more sustainable solution here as well!

Unfortunately, due to human nature, we rely on technology to solve the challenge of living in harmony with our natural world. Fortunately, efficient and cost-effective technologies already exist that do not require ‘black box’ investments rather global political leadership and a Carbon Price to make it happen.