OAK RIDGE, TN - America's vast coal resources have
long been viewed as a potential hedge against future energy needs. Increased
use of this resource, however, is complicated by the emission of pollutants
and concerns about global warming.
One promising approach is the deployment of more efficient energy producing
plants that rely on cleaner, more efficient coal gasification technology.
The DOE Office of Fossil Energy through the National Energy Technology
Laboratory (NETL) has sponsored and performed research and development
of an advanced system known as the Integrated Gasification Combined Cycle
In concept, ICGG will be 30 to 50 percent more efficient than current
coal systems, or in other words, it will provide 30 to 50 percent more
energy from the same amount of coal.
The development and demonstration
of the IGCC technology, which offersthe potential for greater use of coal,
has been a collaborative effort between NETL, other national laboratories,
universities, and industry. Through this combined effort, the IGCC technology
is moving toward commercial acceptance.
Supporting this development is the work of a group of researchers at
DOE facilities in Oak Ridge, Tennessee, who are developing novel uses
for inorganic membranes -- a technology that offers an extremely efficient
means of separating a wide variety of compounds. The Oak Ridge team has
found a potential solution to a key technical issue with IGCC that may
eventually expand the economical uses of coal.
When coal is gasified, a large fraction of the very hot gas produced
is hydrogen. Hydrogen itself is a high-value-added fuel. One way to help
make the IGCC system economical is to have a unit that can separate and
collect a significant portion of the hydrogen for use in more valuable
ways, such as fuel for fuel cells or for use in petroleum refinery catalytic
crackers. This approach is often termed "fuels decarbonization,"
and quite simply refers to the process of converting a hydrocarbon fuel
into a fuel, i.e., hydrogen, that does not contain carbon. For such a
process to be viable, it must include provisions for separating and capturing
carbon dioxide and other oxides of carbon that are produced.
Using inorganic membrane technology, the researchers at the Inorganic
Membrane Technology Laboratory (IMTL) in Oak Ridge, Tennessee, have developed
a process to manufacture a super-efficient, defect-free separation system
that can effectively separate and isolate hydrogen from other gases in
coal-derived synthesis gas.
The Oak Ridge-developed gas separation system consists of a porous membrane
made of a ceramic material. Molecules of hydrogen are extremely small,
as compared to molecules of carbon monoxide, carbon dioxide, and hydrocarbon
gases. The difference in size allows the smaller molecules of hydrogen
to pass through the porous material and away from the remaining gases.
The high-purity coal-derived hydrogen may then be collected and used
as a feedstock for other advanced energy producing technologies, such
as hydrogen-fueled turbines or fuel cells or for chemical and petroleum
processing, such as hydrotreating.
Development of an inorganic porous membrane for separating hydrogen from
very hot gases posed a tremendous technological challenge for the Oak
Ridge researchers. A separation device must be able to tolerate both high
temperatures and harsh environments associated with coal gasification
processes. Laboratory tests have shown that the Oak Ridge-developed process
can provide sufficiently high separation factors. Additional tests will
be made at NETL as well as at the Oak Ridge National Laboratory to determine
their stability under simulated operating conditions.
In a related development, IMTL researchers are developing an economical
means of producing a membrane separation system consisting of a carbon
membrane on a porous metal support. While being developed primarily for
use in petroleum-refining operations to economically recover unused hydrogen
from the refinery purge gases. Variants of either of these systems may
also be used in existing fossil fuel facilities to remove greenhouse gases.
Further development and use of this system promises to help alleviate
global warming concerns with increased fossil fuel use.
Prototype testing of these new products will be conducted at the NETL
and ORNL later this year. Funding for this research was provided through
the DOE's Office of Fossil Energy through the Advanced Research Materials
Program and the Petroleum Technology Program, both of which are administered
The IMTL is located at the DOE's East Tennessee Technology
Park, which is operated by Bechtel Jacobs Company LLC.