Page 98 - Sigmaroc Annual-Report 2023

SIGMAROC ANNUAL REPORT 2023 STRATEGIC REPORT
Our ESG Journey
The calcination process is simply the formula of deriving CaO from CaCO3 using heat.
CaCO3 Energy CaO CO2
The two main sources of CO2 from the calcination part of the process are as follows: Combustion CO2 (~25% to 35%) is produced from the burning of fossil fuels, while process CO2 (~65% to 75%) results from the actual calcination of limestone.
Power and energy CO2 can be reduced through energy efficiency, renewable electricity, fuel efficiency and renewable / alternative fuels. We are actively working on renewable energy solutions and Power Purchase Agreements.
Combustion CO2 can be reduced by energy efficiency and fuel selection, as well as by carbon capture utilisation or sequestration (CCUS). We have achieved success with fossil free lime calcination, achieving 100% substitution by biomass at one site. Our first Carbon Capture unit has also been successfully installed and commissioned.
Process CO2 can only be addressed by CCUS, with our first Carbon Capture unit having been successfully installed and commissioned.
Carbon capture utilisation or sequestration
The emissions from lime kilns are well suited to technologies such as CCUS as they have a higher CO2 content than most post-combustion gases and contain fewer contaminants due to using only limestone as feedstock and, due to product requirements, more stringent fuel quality requirements and typically lower gas filtration temperatures.
Post-combustion capture (PCC) systems constitute a technically and economically viable solution to reduce emissions in a variety of sectors. Retrofitting existing plants with post-combustion capture units may be the only effective and economically viable way to reduce emissions at the stack, without affecting the process upstream. The availability of a range of commercially ready technologies suitable for different types of CO2 point sources is crucial for the wide deployment of CCUS systems. Given the wide ranges of plant sizes and flue gas specifications relevant to different emitting sources, it is unlikely that a single technology could fit best in all cases. Therefore, for effective
process design, it is convenient to consider multiple technologies and select the most efficient and economically viable option to serve the purpose.
In addition to the membrane technology currently in use by SigmaRoc, there are a few other options, some of which are more traditional and geared towards large emitters with each solution having their own opportunities and risks:
• Amine scrubbing is acknowledged as the most mature CCUS solution. Absorption-based processes for the separation of CO2 from flue gases have been widely researched, and their effectiveness has been proven through testing on a variety of scales, from laboratory to commercial. For lime, this solution is both costly and requires a substantial footprint with significant energy consumption and issues with disposal of waste residues.
• Cryogenic capture and separation is a more recent development offered by industrial gas companies as an extension of their in-house process. For lime, this solution is both costly and requires a substantial footprint with significant energy consumption.
SigmaRoc believes that membrane technology is optimally suited to our single kilns / small cluster of kilns due to the proven technology, small footprint, low capital and operating costs and high efficiencies. For our sites that have multiple kilns with larger emission volumes, carbon capture can be done via membrane, but also by other technologies, allowing a flexible approach to carbon capture based on the site, infrastructure and country policies and legislation.
Other technologies, that may be more suited to the SigmaRoc kiln network, are being trialled and investigated including Ocean GeoLoop which employs an all-electric pressure swing process for CO2 capture where a trial plant designed to capture 10,000 tonnes of CO2 is to be established with Nordkalk’s joint venture partner in Norway.
This allows the Company to constantly select the best option for both its operations and its operating jurisdictions.