Cooling is a significant end-use of energy globally and a major driver of peak electricity demand. Air conditioning for example, accounts for nearly 15 percent of the primary energy used by buildings in the United States. Therefore, former ARPA-e Ellen Williams, Director of ARPA-e, was very excited about radiant cooling as it allows for cooling with no energy input.
I was honored to speak with Erik Torgerson from SRI International who worked on the technology. Below are some excerpts from that interview.
Susan Neylon – Can you give our readers a summary of your technology?
Erik Torgerson – Our technology, which we call STATIC, stands for Spectrally Tuned All-polymer Technology for Inducing Cooling. STATIC is a cost effective solution that can be used as either a two layer insulative radiative cooler or a single layer system. It might be easier to think of the two designs as an infrared transparent batt insulation and a stand-off canopy film. In both embodiments, STATIC blocks over 98% of the solar spectrum, but is highly transparent in the infrared band, which allows heat to be removed from the system. Other radiative cooling technologies, such as those coming out of Stanford and the University of Colorado require various vacuum deposited coatings. Those technologies are not infrared transparent, and are focused on developing cooling panels for buildings. STATIC, due to its infrared transparency and all-polymer construction, allows for a myriad of other applications. Imagine those 90 million shade balls that filled the Los Angeles reservoir. We can thermoform STATIC into ball shapes, thus provide shade and the addition of cooling, in the same form factor as the shade balls. Imagine large STATIC canopies providing cooling to livestock in the California Central Valley during the height of the summer. Go to Arizona in the summer and sit outside, you’ll quickly understand the potential market for a passive cooling technology with the flexibility STATIC provides, and wish there was a STATIC awning or umbrella above you.
Susan Neylon – In developing the technology what sort of partnerships did you have to establish?
Erik Torgerson – We had IRADs dating back to 2010 where we worked to develop our concept for daytime radiative cooling, but we struggled to define a market for our technology. The ARPA-e ARID program was a major factor in our ability to transition our ideas into a working prototype. This also allowed us to seek out industry partnerships and we have had a very successful relationship with PPG Industries on this program.
Susan Neylon – What are your plans to commercialize the technology?
Erik Torgerson – The ARID program focuses on addressing water scarcity for the power plant industry. I expect this to be an important problem, but it isn’t a near-term problem. And it is one more affected by regulation than anything else at this point. There is long list of applications, some of which I mentioned, that have a market need right now. Radiative cooling is a nascent technology, one that requires a background in physics to understand. Our focus is on producing a large scale demo that allows us to skip the explanation, and go straight to the “wow” factor of experiencing the cooling power of STATIC firsthand.
Susan Neylon – What made you pursue this initiative in the first place?
Erik Torgerson – It’s a fascinating compilation of multiple physics phenomena, including the difference in the temperature of the sun (6000K) and earth (300K) produces blackbody curves that have nearly zero overlap, allowing the blocking of radiation from one, but allowing transmission of the other, and the large transparency window in our atmosphere right at the peak of the earth’s blackbody radiation. Combine those factors with the current concerns of a warming planet; it is a perfect storm for passive radiative cooling to enter the scene. Researchers predict a 40-fold increase in air-conditioning demand this century. Nobody wants that new demand to be powered by coal. How can we not investigate new ways to tackle this ever growing problem?
Susan Neylon – What keeps you up at night?
Erik Torgerson – Kids keep you up at night. This program has been a favorite of mine. One of the times when all the initial modeling and theory was shown to be correct after we built the prototypes and did the testing. My concerns are the myopia in the energy industry. The Solyndra Effect has scared investors; they just want the next hot app. We as a society need to take the long view, and start thinking about what will keep our kids up at night 20 years from now.