Syngas Chemical Looping
|By Elena Chung, PhD Candidate, Ohio State University, Dept. of Chemical and Biomolecular Engineering|
According to projections by the International Energy Agency (IEA), for at least the next 18 years – until 2030 – approximately 80 percent of the world’s energy consumption will be derived from fossil fuels. Experts predict that petroleum, natural gas and coal will remain the primary energy sources because they are abundant, inexpensive and familiar. World coal consumption, according to the U.S. Energy Information Administration (EIA), is estimated to increase by 50 percent to 209 quadrillion Btus by 2035. In fact, EIA reports that the U.S. derived 21 percent of its primary energy source from coal in 2011, with coal currently generating one-half of the nation’s electricity. However, coal use is controversial because of its associated environmental concerns.
Combustion of coal emits sulfur dioxide (SO2 or SOx), nitrogen oxides (NO and NO2, also known as NOx), particulate matter (PM) and trace heavy metals. Scientists have studied sulfur dioxide and NOx extensively and have demonstrated their contribution to acid rain. Emissions of particulate matter lead to smog formation. The U.S Environmental Protection Agency (EPA) regulates these pollutants following the Clean Air Act. In addition, coal-fired power plants are a major source of carbon dioxide emissions. In March 2012, EPA, following a 2007 Supreme Court ruling, set forth new regulations limiting emissions on new coal-fired power plants. Thus, in order to meet growing energy demands and to utilize domestically abundant coal, carbon capture or clean coal technologies are more relevant today.
Carbon Capture Benefits
Behind meticulously color-coded, tagged stacks of scholarly papers, shelves of textbooks and dozens of student dissertations, Liang-Shih Fan, PhD, sits enthusiastically at his desk scrawling down new ideas and notes at his seemingly disarrayed office at Ohio State University (OSU). When prompted, he gestures energetically to the poster depicting one of his “crowning” accomplishments, the syngas chemical looping (SCL) technology. Fan, OSU professor of chemical and biomolecular engineering, has reason to be excited. As principal investigator on the SCL project, he is leading a joint development effort to scale-up chemical looping technology at the U.S. Department of Energy’s (DOE) National Carbon Capture Center (NCCC), operated by Southern Company in Wilsonville, Ala.
In March 2012, Ohio State and Southern Company signed a collaborative testing agreement to demonstrate the high pressure syngas-to-hydrogen chemical looping process. By early 2013, the construction of a 250 kWth SCL pilot plant will be constructed at the NCCC with sponsorship by DOE’s advanced research agency, ARPA-E. Chemical looping is an innovative process for effectively converting carbon-based fuels to electricity, hydrogen and/or liquid fuels while simultaneously capturing all the carbon emissions. This process could achieve one of the lowest cost and most efficient technologies yet developed for CO2-free energy from coal and biomass.
Such a novel project falls within the scope of ARPA-E goals, which was created to help close the commercialization development gap for high-risk technologies. According to ARPA-E Director Arun
Coal Fired Power Plant
CO2 capture and sequestration technologies can potentially reduce CO2 emissions for coal-fired power plants while simultaneously allowing coal to meet global energy demands. “Coal-fired power plants provide safe, affordable and reliable electricity, but they also release more than 30 percent of U.S. greenhouse gas emissions,” says ARPA-E Program Director Karma Sawyer. However, current CO2 capture technologies can be expensive. Sawyer adds, “The technologies that exist today for reducing those emissions could increase the cost of electricity by up to 80 percent.” Thus, new technologies that can reduce this electricity cost, such as Ohio State’s chemical looping process, are, potentially, the future for coal and next generation coal-fired power plants.
Liang-Shih Fan’s Evolution
For Fan, the promising SCL pilot project resulted from a natural evolution of his lifelong passion in research coupled with his devotion to clean fossil fuel conversion and environmental solutions. “We’ve studied it all – SO2, H2S, NOx and particulates for both air and water pollution,” explains Fan.
Rooted in fundamental research, Fan started in the 1970s with his doctoral thesis on sulfur removal by absorption at West Virginia University (WVU) with his inspiration-mentor, the late renowned Jimmy Wen, PhD, “the King of Coal,” as Wen was known within the research field.
Much of Fan’s research focuses on chemical engineering fundamentals, such as understanding particle science and technology, which can solve real-world pollution control problems. At Ohio State, he continued his work with sulfur removal using limestone. Then he progressed into research on SO2 capture using precipitated calcium carbonate and toxic heavy metal (arsenic, selenium and mercury) removal.
By the late 1990s and early 2000s, Fan and his research group successfully demonstrated the scale-up of these clean coal technologies, such as the Ohio State Carbonation Ash Reactivation (OSCAR) process for flue gas desulfurization and toxic heavy metal removal, and the CARBONOX process for NOx removal from the flue gas of activated carbonaceous fuels as coal char. With increasing public concern about CO2 emissions, CO2 removal became a natural research interest for Fan and his research group starting in 1998. This resulted in development of the carbonation-calcination reaction (CCR) process for CO2 removal. More recently, the calcium looping process and the iron chemical looping processes – SCL and coal-direct chemical looping (CDCL) – were developed for CO2 capture.
Fan’s research has garnered widespread attention and support from both inside and outside the Ohio State community. According to Gordon Gee, PhD and president of Ohio State University, this type of research is important for the state of Ohio and the nation. “Clean coal is important to me as a former president of West Virginia University and current president of OSU. Coal remains a driving force in our country. It’s still very much in use, but we must use it efficiently and cleanly. The work that Fan does is important to sustaining our future, and it’s critical to our national energy policies,” says Gee.
A train carrying a load of black coal snakes its way
Receive livebetter eMagazine; it’s free. One Earth. One Family. Live Better. Be Part of It.