The world's premier test facility for future power plants has achieved
a major milestone - and in the process, raised prospects for a new class
of coal technology that researchers now believe could lead to cleaner,
more efficient and lower cost electric power generation.
The Power System Development Facility at
Wilsonville, Alabama, is the Nation's state-of-the-art test facility
for 21st century power generating technologies.
The U.S. Department of Energy and Southern Company today jointly announced
the first successful test of a new type of technology for turning coal
into gas. The gas could then be used in future turbines or fuel cells
to generate electricity more cleanly than traditional power plants.
The innovative coal gasifier, called a "transport reactor,"
is installed at the Power Systems Development Facility in Wilsonville,
AL, the most advanced test facility for future power technologies in the
world. Southern Company operates the facility for the Energy Department.
The "transport reactor" is based on technology used in refineries
to "crack" crude oil into lighter products, such as gasoline
and diesel fuel. Originally it was intended to be used in the Power Systems
Development Facility to generate hot, particulate-laden coal gas for testing
the effectiveness of advanced pollution control filters. But as the technology
evolved, engineers from Southern Company and Kellogg Brown & Root,
the system's developers, saw its promise as a possible forerunner of a
new class of coal gasification technology.
The innovation is important because coal gasification is likely to be
used increasingly as the core of future power plants. Rather than burning
coal directly, gasification changes coal into a mixture of combustible
gases. In gaseous form, coal can be cleaned of virtually all of its pollutant-forming
With Americans ranking air quality as one of their most important priorities,
coal gasification could emerge as one of the most environmentally acceptable
ways to produce electricity from the nation's abundant coal supplies.
Today, nearly 56 percent of the nation's electricity is generated from
"Future coal systems will have to become increasingly cleaner and
more efficient if the United States wants to continue to use its most
abundant and economical fuel to meet energy needs and sustain economic
growth," said Robert W. Gee, DOE's Assistant Secretary for Fossil
Energy. "We are pleased to report that we are making huge progress
in our clean coal research at the Power Systems Development Facility."
Initially, researchers operated the "transport reactor" as
an advanced pressurized combustor. After nearly 5,000 hours of test runs,
they converted the device to operate as a gasifier.
Since September, the system has successfully operated for more
than 400 hours as a gasifier.
The "transport reactor" could prove to be a simpler, more compact,
and more efficient way to gasify coal - advantages that translate into
lower costs. Because it was developed for a highly fuel-flexible test
facility, it was designed to process a wide variety of coals and other
candidate utility fuels such as petroleum coke.
"Our goal is to make coal both cost competitive and environmentally
comparable to natural gas, and we're almost there," said Dr. Charles
H. Goodman, Southern Company's vice president for research and environmental
"When operating as a pressurized combustor, the transport reactor
performs better than any in the world, and we've now demonstrated that
we can operate it smoothly as a gasifier," Goodman said. "The
performance has exceeded our expectations. We're now in the process of
trying to optimize the reactor."
Goodman said Southern Company is on track to make a decision as early
as next year on whether to build a commercial power plant using the technology.
How It Works
The "transport reactor" is essentially a long tube
in the shape of a loop with coal and limestone fed at the top of a mixing
zone where they contact hot char and react to produce a fuel gas, sulfur
compounds, and a char containing carbon. These are circulated around the
reactor by the gas flow.
The sulfur compounds are collected by the limestone and the limestone
and char are separated from the product gas in a disengager. The char
is partially burned by oxygen or air introduced at the bottom of the mixing
zone to provide the heat to allow new coal to react. A slipstream of char
and sulfur compounds is removed from the system and sent to a sulfator
to recover additional heat and produce inert sulfur compounds.
In addition to virtually eliminating emissions of sulfur dioxide and
nitrogen oxides, the process is expected to surpass the 40-45 percent
efficiencies of today's integrated gasification combined cycle power plants.
Higher efficiencies mean that less fuel is used to produce electric power,
and in turn, emissions of carbon dioxide are reduced. Carbon dioxide is
the major focus of global warming concerns, and the new technology could
reduce the release of this gas by more than a third.
The technology also lends itself to carbon sequestration options -- an
emerging family of technologies that might one day be used to capture
and store greenhouse gases emitted from energy facilities. Oxygen rather
than air can be fed to the reactor which eliminates the large quantities
of nitrogen that would otherwise be present in the gas stream (air is
80% nitrogen) . This allows a concentrated stream of carbon dioxide to
be produced that can be more easily captured and sequestered.
A Source of Gas for Filter Testing
At the Power System Development Facility, researchers plan additional
tests of the transport reactor. It will continue to be used for its original
purpose, generating coal-derived gas to test other pollution control technologies,
such as high-temperature, particulate removal filters supplied by Siemens
Westinghouse Power Corporation and Combustion Power Corporation, who help
fund the project.
The facility is also capable of testing fuel cells, which can be fueled
by hydrogen or by reformed gas from the transport reactor to produce electricity
The $275 million project receives 20 percent of the funds from Southern
Company, the Electric Power Research Institute, Foster Wheeler Corporation,
Kellogg Brown & Root (a business unit of Halliburton Company), Peabody
Group, Combustion Power Corporation and Siemens Westinghouse Power Corporation.
The Department of Energy, as part of its Coal and Power Systems Program,
funds 80 percent.
The Power Systems Development Facility is the focal point for much of
the advanced coal-based power generation research supported through the
Energy Department's Office of Fossil Energy. The Energy Department's involvement
in the facility is overseen by the National Energy Technology Laboratory,
the major fossil energy research arm of the agency.
For more information
about the facility, log on to the Power Systems Development Web site:
There you will find more detailed information on the technologies being
researched at the facility as well as diagrams, flowcharts and photos.