SAGD cogeneration strategy would shrink the carbon footprint of both the Alberta electrical grid and the oil sands
Alberta could simultaneously achieve two of its biggest energy objectives – accelerating the phase-out of coal-fired power and reducing greenhouse gas emissions from oil sands crude production – using a readily available, proven technology, according to two major new studies (Figure 1) by the Canadian Energy Systems Analysis Research (CESAR) Initiative.
Expanding the use of combined heat and power (called cogeneration) technology) at steam assisted gravity drainage (SAGD) oil sands operations would cut more greenhouse gas (GHG) emissions from Alberta’s electrical grid – and at a lower cost – than simply replacing coal with stand alone natural gas-fired power, the studies show.
Figure 1. Cover pages of the two reports (click on the images to download the reports).
At the same time, assigning oil sands companies temporary GHG credits for investing in cogeneration and reducing the province’s overall GHG emissions would also reduce the GHG intensity of SAGD production to be equivalent to, or lower than conventional oil (Figure 2) – something that won’t happen by replacing coal with technologies like natural gas combined cycle (NGCC) to generate electricity.
SAGD cogeneration would also stabilize electricity prices and provide a reliable source of base load and backup power for the expanded renewable energy that the government wants to incorporate into the Alberta grid, as part of its Climate Leadership Plan.
Figure 2. Comparison of the five scenarios for the GHG intensity of SAGD production (SOR=3) in kg co2/bbl (A), and of the public electrical grid in kg co2/MWh (B) when emission reductions resulting from the early retirement of coal are temporarily assigned to oil sands crude production. In panel A, the shaded area shows the range of GHG intensities for conventional oil production and the dashed line shows intensity values when emission reductions are assigned only to those barrels recovered with the heat from SAGD cogeneration.
“Over the next 14 years, much of the province’s electricity generating infrastructure will be replaced, but if this is done with stand-alone thermal power generation technologies, at least 50 per cent of the energy in the fuel will be discarded as waste heat,” says David Layzell, Director of CESAR.
“SAGD cogeneration may be a better alternative, since it can use more than 70 per cent of the energy in the fuel. With SAGD cogeneration, oil sands operations can be part of the solution to climate change challenge, not just part of the problem.”
Cogeneration with gas turbines and heat recovery steam generators using natural gas is a commercial technology. It has been installed in several SAGD projects ranging in size from 80 megawatts to 400 megawatts and proven to be reliable and easy to operate.
“Compared with existing steam generation, cogeneration is much more energy efficient in generating the same amount of steam using less natural gas and electricity. This is a big advantage in the current low oil price environment for SAGD operators,” notes Dr. Song P. Sit, a Senior CESAR Associate and a 30-year veteran in the oil sands business.
“Cogeneration equipment is available from several suppliers, potentially offering price competition. Engineering services to install cogeneration in SAGD are also widely available, which will reduce the risks of install in new projects or retrofit in existing operating projects,” Sit adds.
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