The University of Colorado Boulder has received a $3 million federal grant to develop cooling technology that will enable efficient, low-cost supplementary cooling for thermoelectric power plants.
The grant spans three years and is from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E).
The CU-Boulder research team, led by Ronggui Yang, associate professor of mechanical engineering in the College of Engineering and Applied Science, will develop cold storage modules and a system called RadiCold that cools by infrared thermal emission to enable efficient, low-cost supplementary cooling for thermoelectric power generation.
If successful, CU-Boulder’s design could provide power plant operators a low-cost way to supplement cooling without using as much water as they do now.
“I am confident that we will be successful in developing this novel cooling technology that could be useful for both power plants and buildings,” said Yang.
In thermoelectric power generation, only 40 percent of the energy in the fuel is used for power generation. The remaining 60 percent becomes low-grade heat that needs to be carried away by cooling systems.
There are two types of cooling systems: wet and dry. Wet-cooling systems use water resources such as a river, lake or ocean and pass it directly over tubes containing condenser water, and then return it, warmer, to the original source. Dry-cooling systems use air to cool condenser water.
Most U.S. power plants use wet-cooling technologies because water can cool better than air, which allows power plants to operate more efficiently.
In fact, thermo-electric power plants are among the biggest consumers of fresh water in the world. Forty-one percent of total fresh water withdrawal – about 139 billion gallons per day – is used to cool condenser water. Three percent of the cooling water is evaporated and lost. This has an enormous environmental impact, especially in areas already suffering from fresh water shortages. These systems also release heat waste into the environment, which adversely affects wildlife, said Marta Zgagacz, of the University of Colorado’s Office of Technology Transfer and part of the team that will evaluate the commercialization potential of this innovative technology.
Researchers say dry cooling has the potential to significantly reduce water consumption, but the high cost and low efficiency of current technologies discourage their use.
Improved air-cooled heat exchangers can help overcome these challenges. Since air-cooled heat exchangers can only cool water temperatures as low as the surrounding temperature, supplemental cooling technologies – such as RadiCold – are needed to further decrease water temperatures in certain conditions.
Methods to cool a building roof by sending long-wavelength infrared light into the dark night sky have been known for a long time. However, cooling under direct sunshine, and more critically, manufacturing these cooling systems in a scalable and cost-effective way are areas ripe for research, said Co-Principle Investigator Xiaobo Yin, an assistant professor in both mechanical engineering and in the materials science and engineering program.
A RadiCold surface, which is a metal-coated micro-structured polymer, reflects sunlight and allows radiative cooling through infrared thermal emission for both day- and night-time power plant operation.
Using the new system, a passive zero-energy consumption thermal syphon will collect cold water in a local storage unit beneath the RadiCold surface while a low power consumption pipe network collects the cold water from local storage modules into a central storage system that can be used to cool power plant condensers. Roll-to-roll manufacturing technology will enable effective radiative cooling at a low cost.
“I am excited to work with my colleagues at CU-Boulder to transform innovative materials and component research into engineering systems,” said Gang Tan, assistant professor in the Department of Civil and Architectural Engineering at the University of Wyoming. “I also foresee great potential in building energy savings by developing cooling roof and ceiling systems using RadiCold surfaces.”
Source: University of Colorado Boulder