With respect to new generating technology, AEP has indicated a desire to build large commercial-scale clean-coal plants using IGCC technology. Previously announced plans to build IGCC facilities in Ohio and West Virginia are on hold because the company has been unable to obtain regulatory approvals assuring cost recovery for these projects.
We believe that IGCC technology offers a variety of compelling technological advantages in the race to develop new power generation options in a carbon-constrained world.
IGCC is a clean coal technology that combines two technologies – coal gasification
and combined cycle – to offer the potential to achieve the
environmental benefits of gas-fired generation with the thermal performance
of a combined-cycle plant, yet with the low fuel cost associated with coal.
Coal gasification is the process by which coal is partially combusted with
oxygen and steam to form what is commonly called syngas. The syngas then is cleaned
to remove particulates and other emissions.
Combined cycle plants generate electricity more efficiently and consume less
fuel per kilowatthour of output than do conventional generators. A typical combined-cycle
plant employs one or more gas turbines, a heat recovery steam generator (HRSG) and
a steam turbine. Both the gas and steam turbines produce power.
The technology offers potential for future retrofit of carbon-capture systems at
a lower capital cost and with lower efficiency losses when compared with conventional
pulverized coal technologies.
IGCC technology offers a number of important environmental benefits:
- IGCC has the potential for the best emission characteristics among coal-based technologies.
- IGCC provides for efficient removal of sulfur compounds, particulates and mercury
before the gas is burned instead of removing the compounds from the exhaust gases
following combustion.
- Nitrogen oxide (NOx) emissions are on a par with emissions from a conventional coal-fired
plant equipped with state-of-the-art emission controls.
- Emissions of carbon dioxide are comparable to emissions from a conventional coal
plant. However, should future environmental regulations require the removal of CO2,
an IGCC plant can separate and sequester CO2 from the process at a significantly
lower cost than conventional technologies.
- The IGCC process requires about one-third less water than a pulverized coal plant
- The IGCC process generates less solid waste than a conventional coal plant.
- IGCC plants enjoy greater fuel flexibility than conventional coal plants. IGCC plants
can utilize various coal types, biomass, and other refinery by-products.
AEP has started building one of the first ultra-supercritical (USC) coal-fired units in the nation. The John W. Turk Jr. Plant is under construction in Hempstead County, Arkansas.
USC generation operates at greatly elevated steam temperatures and pressures, making the turbine cycle more efficient, thereby reducing coal consumption and, in turn, emissions levels.
Early supercritical units – such as AEP's Philo Unit 6 – successfully operated at similar elevated temperatures and pressures. However, in that era, metals that could tolerate extreme temperatures over sustained periods of operation were not available. Today’s chrome and nickel-based “super alloys” can perform under these operating conditions for prolonged periods, making USC a practical design for new, more efficient coal-fired power plants.
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