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As a Laboratory Fellow at the Energy Department's Pacific Northwest National Laboratory, Pete McGrail and his team are working to develop a more efficient adsorption chiller that could help the Navy cut its fuel costs. | Photo courtesy of Pacific Northwest National Laboratory.
ARPA-E sat down with Pete McGrail, Laboratory Fellow at Pacific Northwest National Laboratory (PNNL), to talk about PNNL’s adsorption chiller work and how a more efficient air conditioner that could help the U.S. military cut its fuel costs.
Question: Tell us a little about your background and your work at PNNL.
Pete McGrail: I came to PNNL after my post-graduate work at the University of Missouri -- that was about 30 years ago. Since the 1990s, I have been working on nano-structured materials. The initial application for these materials was for hydrogen storage and separating carbon from gas streams for carbon capture and sequestration. Over the years, my team noticed some interesting properties of nano-structured materials that would lend them to refrigeration or heating and cooling applications. That became the seed of an idea around trying to tailor them for use in an adsorption cooler.
Q: Your project aims to design more efficient adsorption chillers by incorporating improvements in materials that adsorb liquids or gases. What is an adsorption chiller, and what are the advantages over more traditional cooling systems?
PM: The typical air conditioner in your home or car uses a mechanical compressor, which uses energy like electricity or fuel to run the mechanical pump. By contrast, adsorption devices use almost no electricity or fuel -- the system uses a thermal-driven pump that employs chemical processes vaporization and condensation to create a cooling effect. Although it seems counterintuitive, the beauty of adsorption chillers is that they use heat to drive an air conditioning or refrigeration cycle.
Q: Earlier this year you were selected to be part of ARPA-E’s BEETIT program (short for "Building Energy Efficiency Through Innovative Thermodevices”) for the Navy. How can this technology help American troops in war zones?
PM: To keep forward operating bases functioning, the military needs to find a way to reduce fuel costs. Fuel delivery can cost as much as $500 per gallon, and troops transporting the fuel may become the target for attack. Many bases use diesel-powered generators to make electricity, but about 2/3 of that fuel’s energy content is exhausted out the tailpipe of the diesel generator, wasted in the form of heat. Rather than wasting that heat, it’s possible to attach a heat recovery unit to the exhaust on the diesel generator that can power the adsorption cooling device. This could potentially reduce a forward operating base’s fuel use by up to 50 percent.
Q: How can working with the military help take your technology to the next step?
PM: The Navy provides great operational clarity around their needs, which is important for us as we design devices. From a financial perspective, they also provide a good indicator of how many units would potentially be purchased after the ARPA-E project terminates. Having those two pieces -- knowing the conditions for success and having an idea of the business case at the end -- is very important to getting private business partners interested in commercializing the technology after the project ends.