Lessons Learned from Carbon Capture Kickstart  | Part 3: The energy, cooling and water mix

Carbon Capture Kickstart Introduction 

In 2022, the Government of Alberta, through Emissions Reduction Alberta (ERA), launched the Carbon Capture Kickstart (CCK) program – a CAD $40 million investment supporting Front-End Engineering Design (FEED) studies for 11 large-scale carbon capture projects across the province. 
 
In our Lessons Learned from 11 Industrial CCS FEED Studies report, developed in partnership with ERA, we share key findings from the CCK program. To help you navigate the report, this blog series will walk through each of the key technical and operational insights from the FEED studies.  

Part 3: The energy, cooling and water mix  

In this blog, we highlight the lessons learned about energy, cooling and water requirements for amine-based carbon capture, which was the most studied capture technology by project teams. 

Energy equations 

Energy has a direct impact on operating costs and overall system efficiency. Carbon capture facilities use thermal energy (heat) for solvent regeneration (heating the amine solution to release captured CO₂) and electrical energy for everything from fans to pumps and heaters. CO₂ compressors can be driven by either steam or electricity. And overall, high energy demands significantly increase the cost of carbon capture activities. 

Thermal and electrical energy can be sourced from the host facility, but this can create a parasitic load (i.e., the portion of energy consumed by the capture system that reduces the host facility’s net output and overall efficiency).  
 
On the other hand, waste heat from the host site (i.e., leftover thermal energy) can be repurposed to provide thermal energy directly or converted into electrical energy for the capture plant. This approach reduces a project’s parasitic load and improves the system’s overall efficiency. To accomplish this, projects need to weigh the costs and operational impacts of using thermal energy, electrical energy, or waste heat from their host facility. 
 
Another option is to install a dedicated auxiliary boiler for thermal energy or a combined heat and power (CHP) plant to provide both thermal and electrical energy to the capture plant. This approach eliminates parasitic load but introduces additional capital costs. 
 
In the CCK program, project teams identified several strategies to improve energy efficiency, including: 

• Optimizing flue gas blower energy requirements to reduce power consumption
• Incorporating a mechanical vapour recompression unit downstream of the regenerator to reduce external thermal energy demand
• Evaluating the operating conditions of the regenerator and CO₂ compressor to determine the optimal operating pressure and temperature, thereby minimizing thermal and electrical demand 
• Recovering waste heat from existing processes to minimize new energy requirements
• Implementing a CHP plant, which can improve the business case for a CCS project by lowering the cost of self-supplied power and generating additional revenue from power sales

Other key insights: 

• Auxiliary boilers or CHP plants can reduce parasitic energy loads, but they will create additional emissions from fuel combustion. These emissions may be directed through the capture plant, impacting the overall design and cost of the plant.
• CO₂ compressor drivers significantly impact energy use. Most proponents started their evaluation with an electrically driven compressor, but as projects developed, some identified steam turbines as a more efficient alternative.
• Carbon capture’s high energy needs are driving companies to take a more holistic approach, integrating energy production (e.g., CHP generated power) with the host facility’s material production to reduce emissions and move towards net-zero electricity production.  

For more on energy requirements, go to Section 4.4. 

Keeping it cool 

In an amine-based CCS facility, cooling is needed for the flue gas and the amine solvent. This keeps everything at the right temperature so CO₂ capture can happen efficiently and safely. It also helps ensure pumps, compressors and other equipment run smoothly without overheating. 
 
There are three different types of cooling systems: water, air and hybrid (water and air). To see a comparison of these methods, go to page 26.  

Choosing a cooling system depends on: 

• Water availability: Sites near abundant water sources may choose water cooling due to its cost-effectiveness. However, in areas with water scarcity or usage restrictions, air cooling may be more practical. 
• Ambient temperature: Air cooling works well in cooler climates, but in warmer regions hybrid or water cooling performs better. 
• Regulatory requirements: Limits on water use or liquid disposal requirements can influence the selection of cooling technology. 

Key learnings from the FEED studies: 

• Air cooling was the prevalent cooling system identified. Notably, facilities using this technology often produce more water than they consume. For example, this can be positive with steam-assisted gravity drainage operations where the extra water can be used in the process. 
• Optimizing for ambient temperature can reduce a system’s footprint and cost. Designing for a temperature slightly below the maximum expected ambient temperature minimizes equipment size and capital cost. The trade-off is reduced cooling efficiency and slightly lower CO₂ capture on the hottest days. However, studies found this reduction to be acceptable when considering overall annual performance and cost savings.
• Seasonal variations impact operating costs. Cooling tower fan speeds and water demand fluctuate throughout the year. In Western Canada, modelling at various ambient conditions is recommended to create a design that is more representative of the annual operating cost of the system. 

For more on the cooling process and lessons learned, go to Section 4.5. 

Wading in on water needs 

While water or hybrid cooling is a major consumer, water is used throughout the whole CCS process: 

• Flue gas cooling: Direct contact coolers use water to lower the flue gas temperature during pre-treatment. 
• Solvent preparation: Demineralized water is used for solvent preparation and conditioning.
• Wash water section: Uses water for cooling and to remove impurities from the treated gas stream before being vented to the atmosphere.
• Amine regeneration:  Water, in the form of steam, is used to strip the captured CO₂ from the rich amine. If water is lost during amine regeneration, makeup water is added to the system. 

Two key insights include: 

• Cooling technology has a significant impact on water usage: Cooling methods strongly influence whether a CCS facility is a net consumer or net producer of water. Flue gas cooling can produce significant condensate that, once treated, can be reused within the process. Study participants noted that when using air cooling they were more likely to be a net producer of water, while those using wet or hybrid cooling typically needed additional raw water sourced from nearby water sources. 
• Additional water demand for some industries: Depending on the capture plant design, implementing CCS may increase water consumption. In industries that currently use little water, such as cement production, project developers may need to build new infrastructure and establish reliable water supply connections to support the added demand.

For more detail on water, go to Section 4.6. 

This part of the FEED study has proven there is a lot to consider when choosing the right mix of energy use, cooling technology and water management. Bringing out the best in each of these systems can help lower costs and improve efficiencies and performance.  
 
Note: The lessons learned in this report are as of July 2024. While the studies were initially intended to be complete by end of 2024, the majority will now be completed by end of 2025. At the time of completion, all projects will publish final public reports summarizing FEED outcomes. Final metrics, including costs and emissions reductions, will be collected, analyzed, and disseminated.