If a number of technical, financial, and regulatory hurdles can be overcome, power generated by integrated gasification combined-cycle technology could become an important source for U.S. utilities. Our overview presents diverse perspectives from three industry experts about what it will take to move this technology off the design table and into the field.
In May, POWER interviewed representatives from two large consulting firms and a national electric energy research organization. From the challenges of adding carbon dioxide (CO2) capture technology to coal-fired plants to the impact of tax credits, the three experts shared their insights about integrated gasification combined-cycle (IGCC) technology. They discussed current and future IGCC technology developments and their predictions about when this technology might become commercially available in the U.S.
Increasingly viewed as having strong potential to provide abundant electricity in the U.S., IGCC technology still has to surmount a number of major challenges. As its name implies, the IGCC generation system integrates two different technologies: coal gasification from the chemical industry and combined-cycle power generation from the power industry. IGCC power plants can use synthetic gas (syngas) derived from a variety of sources such as coal, pet coke, and biomass as their fuel (Figure 1).
1. Dynamic duo. Integrated gasification combined-cycle (IGCC) plants integrate coal gasification with combined-cycle technology and can use synthetic gas derived from coal, pet coke, and other feedstocks. Source: Tampa Electric
Advantages of IGCC Plants
IGCC plants have a number of well-known advantages over traditional coal-fired power plants that use pulverized coal (PC), according to Steve Jenkins, the vice president of gasification services at CH2M HILL Inc., an international consulting, engineering, construction, and operations firm.
IGCC uses less water. IGCC uses about 33% less water for cooling purposes than a similar-size PC plant. This is because about two-thirds of the power generated in an IGCC plant is from the gas turbines and one-third is from a steam turbine-generator, which requires cooling water. Minimizing water needs can be a significant advantage in areas of the U.S. where water use is a major siting issue.
IGCC creates a usable by-product. When using high-temperature gasification technologies, the ash in the feedstock is removed in the form of a glassy, nonleachable slag that can be used in the manufacture of cement or roofing shingles, or as asphalt filler or aggregate. This slag is different from the bottom ash and fly ash produced by most PC units, which can be more leachable. Also, slag can be more easily handled, stored, and transported than fly ash.
IGCC has a carbon capture advantage. Although CO2 capture technologies are available for both IGCC plants (pre-combustion) and PC plants (post-combustion), IGCC plants may have an advantage because the technology required for pre-combustion CO2 capture has already been used successfully on coal gasification (but not IGCC) technology. Enhancements are being made to this technology for better performance in IGCC configuration. Furthermore, some of these capture technologies have the capability to produce the concentrated CO 2 stream at high enough pressures to match the needs of the compressors required to compress the CO2 for transport in pipelines for either sequestration or enhanced oil recovery. However, the costs and performance impacts for CO2 capture vary significantly between IGCC and PC plants.
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