Developing Alternative Energy Sources
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As part of our efforts to sustain a safe and healthy environment, RTI is developing innovative technologies for the production and use of clean energy alternatives.
Polymer Membranes Help Purify Hydrogen
In the February 3, 2006 issue of Science, a team of engineers and scientists at RTI and the University of Texas at Austin reported the development of new polymer membranes for producing hydrogen that bring an energy-efficient, low-cost hydrogen purification process a step closer to reality -- an important stride toward making hydrogen a viable energy alternative.
Because hydrogen is pollution free and can be produced from abundant domestic energy resources, including fossil fuel, nuclear power, and renewable energy, it has been considered a leading choice in the search for alternative energy sources.
One of the major barriers to hydrogen as an alternative motor fuel has been the cost of purifying it. Because hydrogen is produced in high volumes, even a small improvement in purification efficiency could substantially reduce costs. These next-generation membranes could be a huge step in forming the basis of a purification process that makes hydrogen an affordable energy alternative.
With funding from the U.S. Department of Energy (DOE) and the National Science Foundation, the research team developed a family of molecularly engineered, polar, rubbery copolymer membranes that selectively remove larger gases such as carbon dioxide and hydrogen sulfide from the smaller hydrogen. These reverse-selective materials purify hydrogen more efficiently than existing methods, producing hydrogen at high pressures without requiring expensive recompression.
Although plasticization has traditionally been thought of as having a detrimental effect on membrane selectivity, the separation performance of the new membranes is enhanced by their being plasticized by gases such as carbon dioxide and water vapor.
Non-Polymer-Based Methods to Purify Hydrogen
Through other funding from DOE, RTI scientists are also developing non-polymer-based methods to purify hydrogen. One technique uses palladium alloy-based composite membranes developed by RTI. Because these metal membranes operate at higher-temperature process gas streams than do the copolymer membranes, they avoid thermal penalties associated with cooling gas streams down to temperatures suitable for separating polymer membranes. The palladium membranes generate a higher purity of hydrogen than that of the method previously described, but their material and manufacturing costs are much higher.
RTI scientists are also creating a lithium-based sorbent separation process that effectively removes carbon dioxide from hydrogen, thereby purifying the hydrogen. The novel sorbent is regenerable, allowing it to be used again and again. Like the palladium membrane, it operates at high temperatures.
These research projects are part of President Bush's 2003 Hydrogen Fuel Initiative, which dedicated $1.2 billion to reversing America's growing dependence on imported oil by developing the technology needed to make hydrogen cost-competitive with gasoline by 2010.
Reducing Greenhouse Gas Emissions
As part of an effort to reduce global greenhouse gas emissions, RTI International will further develop a novel and cost-effective process aimed at reducing the amount of carbon dioxide released from coal-fired power plants. Funded by the U.S. Department of Energy National Energy Technology Laboratory, RTI will continue the development of a carbon dioxide capture technology that is based on an inexpensive, dry, reusable sorbent. The technology has been in development at RTI for the past five years and is designed to reduce carbon dioxide emissions at coal-fired power plants as well as natural gas plants, cement plants, and petroleum refineries.
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