The Great Plains Synfuels Plant (GPSP) has had the ability to capture carbon dioxide (CO2) through the Rectisol process for sequestration or sale as a byproduct. However, no viable market was found for the CO2 in the early years of operation, and the captured CO2 was simply discharged to the atmosphere. This changed in 2000, when the GPSP began selling CO2 emissions, becoming one of the first commercial coal facilities to have its CO2 sequestered. The program had begun in 1997, when EnCana (formerly PanCanadian Resources) sought a solution to declining production in their Weyburn Oil Fields. Dakota Gasification Company (DGC), owners of the GPSP, and EnCana made an agreement to sell CO2 for use in Enhanced Oil Recovery (EOR). DGC installed two large CO2 compressors and began shipping 105 million standard cubic feet per day of compressed CO2 (60% of the total CO2 produced at the plant) through a 205 mile pipeline from Beulah, North Dakota, to the Weyburn Oil Fields, located in Saskatchewan, Canada, for EOR. The pipeline was constructed and operated by a Basin Electric Power Cooperative (BEPC) subsidiary. The CO2, about 95.5% pure and very dry, is injected into the mature fields where it has doubled the oil recovery rate of the field. In 2006, a third compressor was installed and an additional agreement was reached with Apache Canada Ltd. to supply CO2 for EOR to their nearby oilfields. The three compressors increased CO2delivery to 160 million standard cubic feet (MMSCF; or 8,000 tonnes) per day. Through 2007, over 12 million tons of CO2 had been sold, and over the current expected lifetime of the program, an anticipated 20 million tons of CO2will be stored.
The agreements between GPSP and the oil producers result in multiple benefits, including byproduct revenue for GSPS (sales of CO2) and enhanced oil production from the mature oil fields which increases revenues for the oil producers and offsets imports of oil from outside North America. The use of CO2 from the GPSP for EOR is predicted to allow an extra 130 million barrels of oil to be produced and enable the oilfields to be productive an additional 25 years. The Dakota Gasification Company expects to see increased net revenue beyond the $100 million initial investment in the pipeline and compressors, with some sources placing the pre-Apache Canada Ltd. agreement at between $15 and $18 million per year.1
Additionally, there is the environmental benefit of sequestered carbon emissions; in fact the GPSP remains the only coal-based plant in the United States that captures and sequesters CO2 produced from its processes. In what can be viewed as a synergistic benefit of the Weyburn Project, which created a large CO2 compression and delivery capacity with GPSP's compressors and the pipeline from Beulah to Canada, BEPC recently began the development of a project to capture post-combustion CO2 emissions from flue gases at the adjacent Antelope Valley Power Station, compress it using GPSP's compressors, and deliver it via the pipeline to the same markets.
One of the key factors enabling the Weyburn Project was GPSP's relatively close proximity (205-miles) to an area of mature oil fields (the Williston Basin, which extends from northern North Dakota and Montana into Saskatchewan and Manitoba). Relative proximity to a CO2 buyer is important, as geographical limitations, expensive piping of CO2, and safety are all key factors. Other than the Weyburn oil fields, the oil fields of the Permian Basin in Texas utilize CO2 in EOR, which is supplied from natural sources as well as natural gas processing. Depending on availability and pricing of CO2 in areas having a market for CO2 for EOR, a carbon-separating gasification facility may become a viable, competitive source of CO2 as demonstrated by the success of GSPS in this area.
1. The Sinor Synthetic Fuels Report. J.E. Sinor Consultants Inc. July 2001.