Existing coal-fired power plants, such as the Leland Olds Station near Stanton, N.D., will need to use new technologies such as those being developed by the EERC to meet future regulations related to particulates, acid gases, mercury, and carbon dioxide. (Photo: Chuck Kimmerle/University Relations)

EERC projects focus on new technologies for utilizing coal for energy production with high efficiency, ultra-low emissions

The conflict in Iraq and throughout the Middle East, as well as economic and political instability in Venezuela and Nigeria, continue to threaten world oil supplies, driving home the pressing need for energy security in the United States. In recent months, the United States and Europe have dealt with skyrocketing oil and gas prices; meanwhile, energy demand in emerging economies such as Brazil, India, and China is expected to double by 2020, causing further pressure to increase prices.

In a world requiring increasing amounts of energy, how do we deal with this demand while at the same time addressing the associated environmental issues?

The Energy and Environmental Research Center (EERC) is developing strategic solutions that will provide clean, affordable, sustainable energy in the face of concerns over global warming and other environmental problems. The ultimate goal, according to EERC Director Gerald Groenewold, is “to develop a family of technologies that are more energy efficient and yet result in a zero-emission power plant.”

In the United States, coal is the largest source of electricity and will continue to be for the foreseeable future if its environmental challenges can be met.

Says Michael Jones, EERC senior research advisor, “A zero-emission plant must be our goal if we are to effectively utilize this resource and ensure energy security for the United States.”

The zero-emission thermal electric system
Imagine a coal-fired power plant built with the same alloy used to make F-16 fighter jet engines and equipped with advanced coal utilization systems to improve energy efficiency and reduce fuel use and cost; advanced emission controls to dramatically reduce particulate, sulfur oxide, and nitrogen oxide, and capture hazardous trace metals like mercury; technology to minimize the use of water; and the capability to capture and sequester (store in an environmentally sound geologic location) carbon dioxide emissions to prevent global warming.

“This power plant will soon be a reality, thanks to a wide variety of technologies being developed and demonstrated by the EERC that will offer greatly enhanced efficiency and contribute to a healthier environment,” Groenewold said. Two of the most promising technologies are the oxygen-blown coal combustion high-temperature air furnace and coal gasification.

Oxygen-blown coal combustion high-temperature air furnace
By burning coal in pure oxygen instead of regular air and using advanced emission controls, this advanced power system could hypothetically have no emissions whatsoever. High temperature is the key to improving efficiency.

The further benefit of using pure oxygen is that there is no nitrogen in the flame (normal air is over 80 percent nitrogen) and fewer pollutants are produced. Also, the volume of gas is reduced, allowing the plant to be much smaller and less expensive to build. The cleaned flue gas from oxygen combustion essentially consists of only water vapor that can be reused within the plant and pure carbon dioxide ready for sequestration (i.e., safe storage).

In a demonstration project conducted at the EERC, a natural gas- and coal-fired system was used to test a very-high-temperature heat exchanger, which is the heart of an advanced high-efficiency power plant, otherwise known as an indirectly fired combined-cycle (IFCC) system. A power plant using the IFCC technology heats pressurized air to a very high temperature (2000 degrees Fahrenheit in EERC tests, a world record) in the heat exchanger and uses the hot air to turn a turbine, resulting in a much higher efficiency.

“The results of demonstrations firing with air prove that the efficiency of a power plant using this technology could improve by about one-third, resulting in cheaper, cleaner energy,” said EERC Senior Research Manager John Hurley.

Coal gasification
Coal gasification is the next generation of coal utilization technologies, with only a few commercial systems in existence around the world today. Coal gasification is more versatile than combustion because it can produce a variety of products, including electricity, synthetic natural gas, alternative liquid fuels, and hydrogen.

“The EERC has been researching and developing numerous gasification technologies in the past five decades,” said Tom Erickson, EERC associate director for research.

A promising near-term technology is the transport reactor, a fluidized-bed gasification system that can be optimized to convert a wide variety of solid fuels including different coals, petroleum coke, and biomass to a range of gas products including hydrogen. The system offers simplicity of design and operating flexibility that translates into reduced cost and improved efficiency. This technology has shown great promise for North Dakota’s lignite coal and the brown coals found in Australia.

Advanced emission capture technologies
Advanced emission controls for particulates, sulfur oxide, nitrogen oxide, and mercury are being developed to reduce levels of these pollutants to near zero in future power systems.

By retrofitting power plants with the EERC’s Advanced Hybrid TM filter, more than 99.99 percent of fine particulates can be captured, resulting in gas coming out of the facility that is cleaner than the air that went in. The Advanced Hybrid TM filter is currently being demonstrated at full-scale facilities including Otter Tail Power Company’s Big Stone Power Plant in Milbank, S.D., and the Sacci Cement Company in Cagnano, Italy.

The EERC is working with a variety of clients in developing the next generation of technologies for sulfur oxide and nitrogen oxide removal. These technologies are often coupled with other emission technologies and packaged as multipollutant systems.

“The main focus of recent activities at the EERC is in the control of acid aerosols, which lead to acid rain, in the flue gas of a coal-fired power plant,” said Greg Weber, EERC senior research advisor.

The EERC is recognized as the world leader in understanding and developing control strategies for mercury emissions from coal utilization. Over the last year, the EERC has participated in over $15 million worth of contracts focused on mercury measurement and control including full-scale demonstrations in North Dakota and Texas. Based on the results from numerous demonstration activities, the EERC is commercializing new, cost-effective mercury control approaches for industrial clients.

Technology to minimize the use of water
Future advanced coal combustion or gasification systems can also be equipped with a new technology that will recover water from the plant (the energy industry is second only to agriculture as the country’s largest user of water).

“Our technology will recover a large fraction of the water present in the plant stack gas, conserving scarce water resources, improving power plant efficiency, and reducing harmful emissions,” said Bruce Folkedahl, EERC research manager.

In partnership with Siemens Westinghouse Power Corp., Orlando, Fla., a global leader in the power industry, the EERC has been working on a $1.4 million, two-year contract with the U.S. Department of Energy (DOE) National Energy Technology Laboratory to evaluate and determine how such a technology can be integrated into various existing power systems. Depending on a plant’s configuration and location, recovered water could be reused within the power plant or exported to external customers.

“Integrating this technology with air cooling in a conventional power plant burning North Dakota lignite has the potential to reduce water consumption by 90 to 100 percent,” said Jones. “This would reduce competition between power plants and other industrial customers, agricultural interests, and households for this limited resource.”

Reduce and sequester carbon dioxide emissions
The final aspect of the zero-emission power plant is an option for carbon dioxide sequestration. Currently, the EERC is one of the leading organizations selected by DOE to determine the best ways to reduce the nation’s carbon dioxide emissions. That gas is believed to be a leading cause of global warming.

The EERC’s Plains CO2 Reduction (PCOR) Partnership is one of seven lead organizations around the nation heading up an effort to meet the President’s Global Climate Change Initiative, calling for an 18 percent reduction in carbon intensities by 2012. The PCOR Partnership incorporates the participation of more than 30 public and private stakeholders to identify significant sources of carbon dioxide in the Upper Great Plains and to evaluate the technical and economic feasibility of capturing and storing carbon dioxide.

In a recent article about the Red River Valley Research Corridor and the PCOR Partnership, Sen. Byron Dorgan (D-ND) stated that “UND’s EERC has positioned itself to compete and win major research projects, as evidenced by this prestigious DOE selection.”

The PCOR Partnership region, which includes nine states (Iowa, Minnesota, Missouri, Montana, Nebraska, North Dakota, South Dakota, Wisconsin, and Wyoming) and two Canadian provinces (Manitoba and Saskatchewan), generates about 11 percent (163 million tons) of the annual carbon dioxide emissions for the United States.

“Essentially, we are looking at what will actually work in this specific region and what the best economic and environmental opportunities for sequestration are. We believe the expertise and approaches developed here can be transferred to other regions,” said Ed Steadman, EERC senior research advisor and program manager for the PCOR Partnership.

One potential sequestration option being studied in the first phase of the project, the use of carbon dioxide for enhanced oil recovery, could jointly benefit North Dakota’s coal and petroleum industries and rejuvenate oil production in the Williston Basin in North Dakota, South Dakota, Montana, Manitoba, and Saskatchewan.

Dakota Gasification Company is one of the many PCOR project partners. Its facility in Beulah, N.D., produces carbon dioxide that is sent through a pipeline to Weyburn, Saskatchewan, where it is pumped into an oil field to produce an additional 9,000 barrels of oil a day.

“By pumping carbon dioxide into petroleum reservoirs, the pressure and temperature are such that the carbon dioxide and oil fully mix, providing a significant increase in oil production,” said EERC Associate Director for Research John Harju. “As you can imagine, the economics of 9,000 barrels of oil a day in today’s market are pretty good.”

Harju believes the EERC will be involved in the program’s next phase, which will open for competitive bid in the fall of 2005. “We are in the best position in the region to propose and move forward with Phase II projects,” he said.

Achieving the ultimate goal
“Because of the EERC’s ability to leverage and enhance government research dollars through partnerships with private industry throughout the United States and the world, the Center is on track to make zero emissions a reality,” said Groenewold.

“We believe a zero-emission system is the future for energy production,” he continued. “Achieving energy independence in this country depends on the commercialization of innovative, clean, energy-efficient technologies to meet the energy demands of the world, and the EERC is committed to providing the necessary strategic solutions.”