Study on beneficial uses of CO2 from lignite-based power plants completed

(Prairie Business 2-25-2012) Carbon dioxide capture from lignite-based power plants has three potential opportunities for beneficial use, according to a recently completed study by the Energy and Environmental Research Center (EERC) in Grand Forks, North Dakota. The beneficial uses of purified carbon dioxide include: mineralization, greenhouse gas agriculture and enhanced oil recovery.
 
The study was commissioned by the Lignite Energy Council to identify the most promising technologies for the use of carbon dioxide produced at lignite-based power plants in North Dakota and eastern Montana. The North Dakota Industrial Commission along with the Department of Energy funded the $275,000 study.
 
“Finding beneficial uses of carbon dioxide is important given the capital and operating costs of equipment used to capture and compress CO2,” said Mike Jones, vice president of research and development for the Lignite Energy Council. “Utilities are interested in finding technologies to capture CO2 efficiently and also the most promising technologies that produce the best marketable product.”
 
Researchers at EERC looked at four broad areas that could enhance the value of CO2. Those included mineralization, photosynthetic reduction, chemical reduction and electrofuels. The study included a market assessment and an economic evaluation to determine the best current technologies.
 
Mineralization is a process where minerals are formed from the CO2 gas and is a relatively new concept. The gas is used to form a carbonate or bicarbonate, which turns the gas into part of a solid product, which may have commercial value. The process also requires a source of alkalinity, such as fly ash from lignite-based power plants.
 
“This technology can actually be used to make aggregates that can be used for roads or as a component for concrete,” Jones said.
 
The study looked at 19 different mineralization processes and companies. However, the most advanced use of CO2 in mineralization is currently only at pilot-scale tests. Also, the cost of aggregate from mineralization would be about twice the cost for gravel that is mined and, currently, a premium price is being paid for lignite-based fly ash because it is used in stabilization of waste pits in the western North Dakota oil fields.
 
A second beneficial use of CO2 involved growing plants in a greenhouse that is supplied with CO2, heat, light and humidity controls for maximum productivity. Common products grown in this type of greenhouse environment include flowers, specialty fruits – such as tomatoes – and vegetables. Lignite-based plants may eventually see a market for CO2 used at greenhouses that are built near the plants because low-grade heat and supplemental electricity from the power plants can also be used.
 
Finally, the CO2 can be used for enhanced oil recovery. The Great Plains Synfuels Plant at Beulah, North Dakota, captures about 3 million tons of CO2 per year, which is sold for enhanced oil recovery operations in the oil fields near Weyburn, Saskatchewan.
 
The Lignite Energy Council is a regional trade association representing North Dakota lignite producers, electric utilities and 380 businesses providing goods and services to the mines and plants. The lignite industry generates approximately $2.9 billion in gross business volume within the state.
 
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