Today’s commissioning of SaskPower’s Boundary Dam Carbon Capture and Storage (CCS) Project at the Boundary Dam Power Station near Estevan, Saskatchewan is of global significance as it is the world’s first commercial-scale power plant with a fully integrated carbon capture system.
The capture system at Boundary Dam will remove 90 percent of the carbon dioxide (CO2) emissions generated from a power plant producing 110 megawatts of electricity. The flue gas leaving the power plant is passed through an amine solution to selectively remove CO2. The CO2–rich amine solution is then heated to drive off (strip) the CO2, which is then compressed and transported off-site for use in enhanced oil recovery (EOR) operations at a nearby oil field. The amine solution, after having been stripped of the captured CO2, can then be used again.
More to Cost Than Required Investment
With a price tag of $1.35 billion, at first glance Boundary Dam would seem to be expensive. But if you look a bit deeper, there is more to the cost story than just the investment required for this particular facility.
It is a well-established engineering axiom that any first-of-a-kind (FOAK) facility is significantly more expensive than subsequent similar facilities. The experience and lessons learned from the design, construction and operation of the Boundary Dam project can be applied to reduce the cost of subsequent projects. SaskPower has stated that a capital cost reduction of up to 30% is readily achievable for a similar project.
Significant Engineering Innovations
From an engineering perspective, Boundary Dam has fostered significant innovations in CO2 capture system design that could come to represent the new state-of-the-art for capture from a coal fired power station. The following achievements are particularly noteworthy:
- Prior to construction, there was great concern that a significant fraction of the energy generated by the power plant would be needed to run the carbon capture system. This diverted energy is referred to as parasitic power. Ultimately, the system design was able to reduce the parasitic power requirement by one-third.
- The project uses a single system for sulphur dioxide (SO2) removal and CO2 separation, which reduces costs by not requiring a separate flue gas desulphurization (FGD) unit. Heat integration between the two processes minimizes steam (parasitic energy) requirements.
- The amine reactors are made of concrete with internal linings. This results in significant cost reductions compared to stainless steel (which was initially thought to be needed) while maintaining process performance and corrosion tolerance.
- A rectangular/square design instead of a circular design allows for easier and cheaper on-site construction.
- Prefabrication and modular design saves project time and onsite costs. The pre‑fabricated CO2 stripper is reported to be one of the largest in the world. The design, fabrication, transportation and installation experience associated with this large equipment is valuable information to other CCS project developers.
- Developed procedures for commissioning and standard operations can be applied to new projects.
Learning By Doing
Cost reductions of the type noted for Boundary Dam are common in the evolution of environmental control processes and systems. In a 2005 paper, researchers from the University of California and Carnegie Mellon University described an analysis of cost reductions realized in FGD installations over time. Their findings indicated that the maturation of FGD technology over a 20 year period led to a 50 percent decrease in capital costs. In large part, these capital cost reductions can be tied to improvements in reliability. Increased reliability allowed designers to eliminate costly redundancies such as spare absorber modules. Additional capital cost savings resulted from technological trends that provided economies of scale, lowered unit costs, eliminated unnecessary components, and reduced reagent preparation costs. In addition, the analysis indicated that operating costs were reduced, on average, to 83 percent of their original values for each doubling of cumulative power generation through “learning-by-doing.” This value of 83 percent is known as the “progress ratio,” and is comparable to progress ratios found in many other industries.
There is ample reason to believe that similar cost reductions can be achieved as more experience is gained in carbon capture technology. The progress made in terms of cost just in the Boundary Dam project can be seen as a significant source of optimism for the future of carbon capture. As the proponents of the Boundary Dam project engage in a well-deserved celebration of the success of their efforts, CCS stakeholders will look to Saskatchewan for lessons learned and knowledge shared that can help inform their own projects under development – yet another reason to celebrate!