Abby L. Harvey
GHG Monitor
10/9/2015
One year after officially coming online, SaskPower’s Boundary Dam Unit 3 remains the world’s first and only commercial-scale post-combustion coal-fired carbon capture and storage project. The last year has been one of expanding knowledge, and SaskPower is happy to share the lessons it has learned, SaskPower CEO Mike Marsh told GHG Monitor on the sidelines of this week’s United States Energy Association’s Energy Supply Forum. “This is real, it is the future, and we’re happy to be a part of it,” Marsh said.
A few modifications have had to be made throughout the project in Estevan, Saskatchewan, including some adjustments to the steam path on the boiler. “We’ve modified the existing boiler, so it looks different the way we bring the steam off the superheater and the reheater sections are different than a traditional boiler. We have to be able to ferry the output from the turbine generator set in response to load and still maintain steam flow to the carbon capture," Marsh explained.
These are the kinds of lessons future CCS developers can glean from the Boundary Dam project, and SaskPower hopes other utilities can learn from its progress.“There’s a whole bunch of technology issues there, things like that [the steam path] I think any engineering team would be very, very interested to understand. It’s the unknowns on something like this where you think you’ve captured most of it in your initial design but as with any first-of-its-kind you’re always learning,” Marsh said.
The project, a retrofit of the power station’s aging Unit 3, has performed well in its first year of operation, Marsh said. “We had net megawatts of 139 off of a gross megawatt rated unit of 150 [before the retrofit]. When we refurbished this unit, we upgraded the design so with the same amount of coal that is used we can now achieve a better efficiency. We can achieve 161-162 megawatts when we’re not running the carbon capture facility. When the carbon capture facility is running, we’ll have a net megawatt of 120 so essentially 40 megawatts of parasitic load. At 90 percent capture we are emitting only 354 tons per day, as opposed to 3,600 prior,” he said during his presentation at the forum.
Another exciting statistic to come out of the first year of operation is the 99.9 percent purity of the CO2 stream. This makes it close to food grade, Marsh explained. “For food processing plants, for beverage facilities, you can clean up this just a little bit, and there is a whole other market that opens up for the sale of CO2, so we’re exploring that right now at the present time.”
Currently, the plant’s captured CO2 is used in two ways. The vast majority is sold to Cenovus for use in enhanced oil recovery, a revenue stream that has been crucial to the project, Marsh said during the interview. “At this point right now, just because we went with a first-of-its-kind, we needed the revenue from a CO2 stream to help make the economics work when we made that decision back in 2011,” he told GHG Monitor.
The CO2 remaining after the company has met its contractual obligations to the oil company is sent to Aquistore, a geologic storage project run by the Saskatchewan-based Petroleum Technology Research Center. Aquistore consists of two wells located on SaskPower land, less than 2 miles from the Boundary Dam plant. CO2 stored at the project will be injected more than 2 miles underground into the Deadwood and Winnipeg deep saline formations.
At this point, SaskPower has been able to contribute very little CO2 to the project, though that amount is hoped to increase in coming months. Unit 3 is currently off-line for an annual six-week overhaul, Marsh said in his presentation, during which time the company will “change out some of the heat exchangers, change out the normal things you would do on a big facility like this.” Following that overhaul, SaskPower should be able to boost the amount of CO2 sent to Aquistore, according to Marsh.
Based on performance in the first year of operation, SaskPower engineers report that the cost of future facilities could decrease rather significantly. “The estimates that we are getting back through our design team are indicating we could probably reduce the cost on the next facility in the order of 20-30 percent, we’ve learned enough in one year to know that we can take and modify some of the processes and really get this down to a price that lowers the capital cost,” Marsh said.
The final project was constructed at a total cost of about $1.4 billion, up from the original estimate of $1.24 billion. Cost overruns and construction delays were attributed to an asbestos scare and unanticipated engineering work. The asbestos issue alone halted nearly all construction work for almost a month, costing SaskPower $30 million, the utility reported. New engineering specifications cost an unanticipated $25 million to build in boiler reinforcement for Unit 3, and SaskPower also paid about $30 million to remove lead paint from the power unit. Other unforeseen engineering work cost the company another $35 million.
SaskPower is waiting a bit longer to make a decision on future projects, however, despite the positive reports. Boundary Dam Units 4 and 5 are reaching their end of life and will need to be refurbished in the next few years. The company expects to make a decision on whether to pursue CCS retrofits on those units until after Unit 3 has performed a full year at its designed performance, a milestone not yet reached. “We expect to be making that decision on [Units] 4 and 5 probably at the end of 2016 beginning of 2017,” Marsh said.
