Public Power - September 2008 - (Page 27)

Until recently, there were few—if any—workable options for capturing carbon emissions from the flue gas streams of U.S. coal-fired plants. That is changing. Several post-combustion technologies are in various stages of research, development and demonstration. While these technologies can be employed in new conventional coal-fired plants, it is their use as retrofit systems on existing plants that has piqued utility interest—and prompted a number of demonstration projects. Separating carbon dioxide from flue gas streams is not without its challenges, as the Department of Energy’s National Energy Technology Laboratory (NETL) points out. flue gas by Powerspan’s ECO technology or another air pollution control system, the CO2 is captured in an aqueous ammonia solution. The solution is regenerated to release the CO2 and ammonia. The ammonia is then recovered and returned to the scrubbing process for reuse. The CO2 is processed into a form that is ready for use or sequestration. Ammonia is not consumed in the scrubbing process, and no separate byproducts are created. The technology can be used at both existing and new coal plants. It is designed as an add-on system that could be used when needed. It is particularly advantageous for plants that employ ammonia-based scrub- sequestration projects. The MRCSP plans to inject a small amount of the CO2 captured during the pilot—between 1,000 and 3,000 metric tons—into an 8,300-foot well, which ends in a deep saline reservoir. The aim is to determine the potential suitability for carbon sequestration in the area. MRCSP expects to use the information it gains on rock strata to develop a more exact profile of the rocks underlying the sequestration site, which will confirm its suitability for CO2 sequestration. The aim of the Burger plant pilot is to confirm the technology’s process performance and energy requirements and provide While the nation’s coal-fired power plants emit nearly 2 billion tons of carbon dioxide into the atmosphere annually, they also provide half of the nation’s electricity. Among those challenges, say NETL researchers, are: • CO2 is present at diluted concentrations and low pressure, which dictates that a high volume of gas be treated. • Trace impurities (particulate matter, SO2, NOx) in the flue gas can degrade sorbents and reduce the effectiveness of certain carbon capture processes. • Compressing captured or separated CO2 from atmospheric pressure to pipeline pressure represents a large auxiliary power load on the overall power plant system. “There has been a lot of progress in the area of solvents, such as aqueous ammonia processes,” said Tom Feeley, NETL’s technology manager of innovations for existing plants. One of those processes—developed by Henry Pennline and fellow NETL researchers under a cooperative agreement with New Hampshire-based Powerspan Corp.—was patented by DOE and licensed to Powerspan in 2007. To date, it is the only U.S.-issued patent that covers a regenerative process for carbon dioxide capture with an ammonia-based solution. Here’s how the technology—known as ECO2—works. After SO2, NOx and fine particulates have been removed from the www.APPAnet.org bing of emissions. Market drivers—such as a cap-and-trade system or a carbon tax—will stimulate demand for carbon capture and storage technologies, such as ECO2, but some utilities are not waiting for a federal emissions mandate. A pilot test of the ECO2 technology will begin this summer at a conventional coalfired plant in Ohio. Based on extensive laboratory testing, Powerspan developed the design parameters for the system that has been built at FirstEnergy’s 413-MW R.E. Burger facility. The pilot will process a 1-MW slipstream drawn from the outlet of the plant’s 50-MW ECO—a multi-pollutant control—unit. The system is designed to produce approximately 20 tons of sequestration-ready CO2 per day and is expected to achieve a 90 percent capture rate. The pilot is expected to run through 2009. Capturing the carbon dioxide from a coal-fired plant is only half the equation, of course. The other half is ensuring its use or storage. As it happens, FirstEnergy’s Burger plant was selected in 2006 as a carbon sequestration test site by the Midwest Regional Carbon Sequestration Partnership (MRCSP), one of seven regional organizations set up by DOE to research carbon the basis for cost estimates. “If successful, the technology could help keep existing coal-fired power plants economically competitive in a carbon-constrained world,” said Frank Alix, Powerspan chairman and CEO. The pilot will also pave the way for two commercial-scale demonstrations of the technology, one in North Dakota and one in Texas. Antelope Valley demonstration. One of the largest generation and transmission co-ops in the country, North Dakota-based Basin Electric, has 120 members that provide power to more than 2.6 million consumers in nine states. Like other electric utilities, Basin Electric believes regulation of carbon emissions is coming, and it wants to be ready. “Technology development takes time,” said Daryl Hill, the G&T’s media relations coordinator. “We wanted to get out ahead of the curve. We wanted to see what technologies are out there, and how one of them might be used at our facilities.” That search started in 2007 with a request for proposals for a technology demonstration project. Basin Electric evaluated the proposals for technical and commercial feasibility, project business model and contractor approach, environSEPTEMBER 2008 27 http://www.APPAnet.org

Table of Contents Feed for the Digital Edition of Public Power - September 2008

Public Power - September 2008 Contents Perspective 10 Questions What’s Good About RTOs? Capturing Coal’s Carbon Carbon Safety Valves Greater Glass, Greater Savings Getting Customers to Embrace Compact Fluorescent Lights LEEDing Green Kansas City Shows How to Build Green For Governing Boards Safety Community Broadband Hometown Connections Parting Shot

Public Power - September 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.