Canadian Consulting Engineer

C02 storage needs careful engineering to avoid risks, say researchers

March 22, 2010
By Canadian Consulting Engineer

A study by a team of researchers led by the University of Calgary into whether it is technologically feasibl...

A study by a team of researchers led by the University of Calgary into whether it is technologically feasible to store huge amounts of carbon dioxide underground was released on March 12.
The so called “Wabamum Area C02 Sequestration Project, or WASP” is the first comprehensive study of large-scale C02 storage to have all the findings made fully available to the public. It involved studies of geology, reservoir fluids flow and geomechanics, which province-wide studies don’t include.
The WASP project team undertook research in the Wabamum Area of Alberta, which is where most of Alberta’s coal fired power plants are located. The study took 16 months.  While their conclusions were overall positive, they warn that it is necessary to do more research – including drilling test wells on any site before going ahead.
Professor David Keith of U of C, one of the researchers, said in a press release: “Before a commercial-scale CCS operation can begin, there needs to be an array of geological and engineering studies done on the proposed CO2 storage reservoirs, to assess risk and facilitate safe and effective storage.” Keith is director of the ISEEE Energy and Environmental Systems Group and a professor of chemical and petroleum engineering at University of Calgary.
One finding, for example, was that the Nisku geological formation that is the primary target for C02 storage has brines that contain “significant concentrations of dissolved hydrogen sulphide.” This poisonous gas “could potentially mix with the leading edge of the plume of pure C0 injected into the formation.” Consequently, Keith warned: “This is an important and unique finding by WASP that underscores the importance of open-ended risk assessment, and highlights the need to characterize the geochemistry of fluids in the formation prior to starting a C02 storage project.”
The WASP team was examining the possibilities and costs of storing 20 million tonnes annually of C02 over 50 years in a 5,000 square-kilometre area.
They found that about half of that — 500 million tonnes of C02 — can be stored without managing the pressure of the geological formation. This volume of storage is equivalent to half the emissions for 30 years from all of Alberta’s centrally located coal-fired power plants.
The team therefore concluded that there is enough storage capacity in the area and that costs of injecting the C02 into the ground were relatively low — about $3 per tonne of C02. However, Keith noted that additional costs to capture, pressurize and transport the C02 could be 10 times the storage costs.
Sponsors of the WASP project included governmental organizations such as Alberta Energy Research Unit, Natural Sciences and Engineering Research Council (NSERC), several oil and gas companies, and Golder Associates.
The results are to be used by industry partner TransAlta Corporation which has received $770 million in provincial and federal funding for C02 projects. TransAlta plans to capture one million tonnes of C02 at its Keephills 3 coal fired power plant in the Wabamum area.
Carbon storage, or “sequestration,” is seen as being a possible technological answer to reducing the amount of carbon dioxide industry and power generation emits into the atmosphere contributing to greenhouse gases.



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