Building Saskatchewan's greener future

The prairie province of Saskatchewan in Canada is on an ambitious journey towards a low-carbon energy system. As well as investing substantially in wind energy projects and investigating renewable energy options such as biomass, it is developing one of the world’s largest commercial-scale carbon capture and storage (CCS) project.

Coal is an abundant, readily available and indigenous resource in Saskatchewan, and the Boundary Dam coal-fired power station has been generating electricity for over 50 years.

Saskatchewan corporation SaskPower, the power station’s owner, worked with Cansolv Technologies Inc.¹ to evaluate the options for reducing emissions of carbon dioxide (CO₂) and sulphur dioxide (SO₂). It chose to rebuild, modernise and upgrade one of the plant’s ageing coal-fired units and integrate it with a CCS system.

The unit did not have flue gas desulphurisation or carbon capture technology, so Cansolv suggested its integrated CO₂- and SO₂-capture process.

Stéphane Charest, Business Development Manager, Cansolv Technologies Inc., explains: “Essentially, there are two separate absorption columns, with two independent solvents, that operate in series. The post-combustion flue gas stream goes first to the SO₂scrubbing system and then to the CO₂ capture system. The two capture systems are heat integrated so that the available energy in the SO₂ scrubbing system is used in the CO₂one. This reduces the net utilities demand and the parasitic steam load on the power plant for carbon capture.

Charest adds that there are other important cost and environmental benefits. “Cansolv technology uses regenerable amines to capture both CO₂and SO₂, which means no direct waste by-products are generated,” he explains. “For example, when comparing SO₂scrubbing with wet limestone gas scrubbing technology, which produces contaminated waste, regenerable amines can reduce project operating costs, as the effluents are minimal. Further, limestone is not native to Saskatchewan, which not only implies additional transportation costs but also increases the project’s carbon footprint (life-cycle analysis).”

Importantly, the gases that will be extracted can be put to good use. The SO₂ captured from the flue gas will be converted into 60 tonnes per day of a marketable by-product: sulphuric acid. Among its many other potential applications, the acid can be used as a feedstock for the local fertiliser industry.

In addition, one million tonnes a year of CO₂ will be captured from the coal-fired unit, which is equivalent to the emissions from over 200,000 passenger cars. This will be compressed, transported through pipelines and used for enhanced oil recovery in nearby oilfields. Permanently stored in deep geological formations, the greenhouse gas will not contribute to climate change.

CCS: Meeting the energy challenge

The International Energy Agency says that CCS will play a vital role in worldwide efforts to limit global warming. It expects this relatively low-cost technique to contribute about one-fifth of the emission reductions that are required to stabilise the concentration of greenhouse gas in the atmosphere by 2050. However, it warns that uptake must be swift. 

The Saskatchewan project is scheduled to become operational in 2014, and successful operation of this carbon capture technology may lead to retrofitting of the three other units at the Boundary Dam power station. These units are also ageing, and Cansolv’s technology could be a cost-effective means of extending their useful lives and enabling SaskPower to continue using the region’s coal reserves (said to be equivalent to 300 years of years of power production at current production levels). This would be a huge boost for SaskPower.

But Mike Monea, President, Carbon Capture and Storage Initiatives, SaskPower, says that the project’s importance extends beyond Saskatchewan. “Right now, this is the project that the world is watching,” he says. “Its importance at both the local and international levels cannot be overstated. Given the volatility of natural gas prices, the urgent need to reduce greenhouse gas emissions worldwide and the available supply of coal, there is considerable interest in finding more environmentally sustainable ways to use coal in electricity production.”

Charest agrees. “This will be the first commercial scale CCS venture to be applied at a power plant. Others that have been developed to date have yet to receive approval for construction,” he says. “SaskPower is the first company to do this on a commercial scale, and the industry is waiting to see how it works. So, it will be important for the emission reductions that it will deliver and because it will help to determine the technical, economic and environmental performance of clean coal CCS technology.”

For more information contact Stéphane Charest.

^{1. Cansolv Technologies Inc. is wholly owned by Shell Global Solutions International BV. CANSOLV is a Cansolv Technologies Inc. trademark.}