Canadian clean power coalition project: the evaluation of options for CO2 extraction from existing and new coal-fired power plants
The Canadian Clean Power Coalition (CCPC) was created in 2001 to protect and enhance Canada’s vast coal and other carbon-based resource wealth, and to ensure that environmental public policy decisions recognize that these resources are a Canadian asset, not an environmental liability. CCPC’s membership includes seven Canadian coal and coal-fired electricity producers: Atco, EPCOR, Luscar, Ontario Power Generation, Nova Scotia Power, SaskPower, and TransAlta Corporation. Together, these represent over 90% of Canada’s coal-fired power generators and coal suppliers. The Coalition also includes the US Electric Power Research Institute (EPRI) and the International Energy Agency (IEA). Support and additional research funding for Phase I has been provided by industry stakeholders, Natural Resources Canada, the Alberta Energy Research Institute (AERI), and Saskatchewan Industry and Resources (SIR).
To achieve its mandate, the CCPC has undertaken to demonstrate technologies for use in new coal-fired power plants to control air emissions including carbon dioxide (CO2), nitrogen oxides (NOx), sulphur dioxides (SOx), mercury (Hg), and particulates (PM). The first phase of the demonstration project, carried out over 2003 and 2004, assessed three existing technologies for coal-fired power plants which reduce all emissions, including CO2, to levels equivalent to or below that of gas-fired power plants. The technologies considered in this phase included integrated gasification combined cycle (IGCC), ‘oxy-fuel’ combustion, and amine scrubbing of pulverized coal. These technologies were evaluated with three coal types: eastern bituminous, western sub-bituminous, and lignite coals. Engineering studies determined the capital and operating costs, the cost of electricity produced (with CO2 removed), and the cost per tonne of CO2 avoided. These initial studies also evaluated the potential utilization of CO2 generated in western Canada for enhanced oil recovery (EOR) and storage in depleted oil reservoirs or deep saline aquifers. Finally, the first phase of the project identified process optimization and technology enhancements to improve the competitiveness of gasification of low rank western Canadian coals. The conclusions drawn from this first phase include the following.
IGCC performance and costs are highly dependent on the rank of the coal: the higher the rank, the lower the plant costs. Only very limited information is available for IGCC with low-rank coals incorporating CO2 capture, and further work is needed to optimize IGCC performance with these coals. There is considerable potential for improving IGCC performance and reducing costs by using blended fuels such as coal/coke mixtures, in locations where these fuels are available. IGCC has the unique advantage over other technologies in its capability of co-producing electricity, hydrogen, and heat (polygeneration). Attractive business cases could be developed where such mixed fuels are available and markets exist for the coproducts. Refineries, chemical complexes, and heavy oil plants in Saskatchewan and Alberta have these attributes and will be the focus of Phase 2. Further improvements can also be made in the power cycle by using advanced gas turbines and optimizing the performance with higher hydrogen content in the fuel gas, thereby increasing overall CO2 removal.
Considerable effort was expended in Phase 1 to optimize the amine scrubbing process through a highly heat integrated split flow amine cycle. Indeed, it proved more cost effective to design for 95% CO2 removal as opposed to the 90% achieved in the retrofit study. These enhancements improved amine scrubbing relative to the other technologies, which were not optimized to the same extent in the study. Phase 2 will evaluate additional options that exist with this technology.
Oxyfuel technology is at an early stage of development and showed considerably higher costs relative to the other technologies.
Phase II, started in late 2004, aims to optimize the design and develop business cases for one or more demonstration plants to be operational by 2012. These plants will be designed to produce clean power as well as steam and hydrogen for the recovery and upgrading of bitumen (polygeneration) and the utilization of CO2 for enhanced recovery of conventional oil. The unique combination of feedstock and product options favour demonstration and commercialization of clean coal polygeneration plants in western Canada.