US-based start-up Sublime Systems is ‘electrifying cement production and forgoing the kiln entirely’ — which is the most energy and fossil fuel-intensive part of the cement manufacturing process, according to a new World Economic Forum report
“Population growth and urbanization are driving the construction of cities equivalent to the size of New York City every month,” Nollaig Forrest, the Chief Sustainability Officer at Holcim, noted in a report carried by the World Economic Forum, writes Pooja Chhabria.
“Cement is a key ingredient in concrete, which is the most used construction material because it is local, affordable, versatile, recyclable, high-performing and resilient,” said Ms Forrest.
“But getting the materials to produce cement and concrete is putting increased pressure on our planet and its natural resources.”
Concrete and cement account for approximately 7% of global CO2 emissions, and if no action is taken, this number could grow dramatically, effectively undercutting decarbonization efforts in other sectors. The WEF has highlighted three solutions to cement emissions and Dr Leah Ellis represents one such solution towards decarbonising the manufacturing process by changing how cement is produced.
As co-founder and CEO at US-based startup Sublime Systems, Leah says they are building the ‘electric vehicle of cement-making’.
“We replace the fossil fuel kiln with an electric chemical approach,” she explains.
The most common method to produce cement today creates two sources of CO₂ emissions: about 40% comes from the burning of fossil fuels to heat kilns at 1300-1450°C, and about 60% is released during the thermal decomposition of limestone into carbon dioxide and lime, an essential element of clinker which is the main ingredient of cement (about 70%).
“We’re replacing a high-temperature, combustion-fuelled, fossil-fuelled kiln with an ambient temperature process that can be more efficient thermodynamically and make the same hardened cement that we’ve been using for millennia,” Leah says.
“And we can ultimately make it at the same cost.”
This approach to cement-making has been proven in the lab, and the team now remains focused on building scale. “We have scaled up in the past three years from a gram of cement in the lab to 100 tons per year in our pilot plant. But that is still a drop in the bucket,” Leah admits.
“We have to go from our pilot plant capacity today to a demonstration-scale capacity – so this is the minimum viable industrial scale plant, which is about 100 tonnes daily.
“And from there, we have to scale up to a million tonnes per year if we need to be relevant in the industry, produce relevant volumes and compete on cost.”
But she remains optimistic about the industry moving from chemistry-based standards to performance-based standards. “That means you’re defining cement not just by its chemistry but by its properties,” she says.
“So, does this cement react with water in the same ratios? Does it harden and form a gel in the same amount of time? Does it have the same strength and durability measured by specific tests?
Why is this important? “Because defining cement by its performance and not its chemistry allows you to solve the real problem: to have a high-performance, low-carbon building material.”
The World Economic Forum, in collaboration with Boston Consulting Group and industry input from the Global Cement and Concrete Association (GCCA), has examined the manufacturing and use of concrete to develop a seven-part framework that helps scale low-carbon design and reduce emissions from cement and concrete production.
It suggests pulling three key levers to reduce concrete emissions in construction projects by up to 40% by 2030:
1. Manufacturing process decarbonization, including tactics such as production efficiency and renewable electricity.
2. Specifying lower-carbon cement blends, which use supplementary cementitious materials to reduce the volume of cement in production, thus reducing the blend’s carbon footprint.
3. Optimizing the volume of material used in projects by applying design techniques that reduce the overall volumes of material required and balancing trade-offs between the carbon intensity of cement products and the required volumes.
Read the full WEF report HERE
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