For Greg Glatzmaier, the road between innovation and implementation runs along a dusty stretch of highway about a dozen miles south of Boulder City, Nevada, where his patented idea could solve an industry problem. The destination for his idea is Nevada Solar One, an outpost in the desert where 186,000 parabolic shaped mirrors tilt to capture the sun’s rays.

Greg Glatzmaier tests the high-temperature thermal/mechanical stability of sealants that are being used in equipment installed at the Nevada Solar One power plant. The process reduces trace levels of hydrogen in the power plant and maintains its original design efficiency and power production. Photo by Dennis Schroeder, NREL

“When the plant first opened, there was nothing around it but open desert with mountains to the west and east,” said Glatzmaier, a senior engineer in the Thermal Energy Science and Technologies group at the National Renewable Energy Laboratory (NREL). “The only other landscape feature is a dry lakebed north of the plant.”

Since Nevada Solar One began operations in the summer of 2007, other utility-scale solar power plants have opened in that lakebed. Nevada Solar One is the only concentrating solar power (CSP) plant in the region, however, and the technology faces a unique set of challenges.

The CSP facility uses concentrated beams of sunlight to heat a fluid flowing through 20,000 tubes to as high as 752 degrees Fahrenheit. The process creates steam to spin a turbine that powers a generator and produces electricity. Over time, however, the heat transfer fluid begins to break down and form hydrogen, which reduces the effectiveness of the process. Tiny metal pellets in the tubes absorb the hydrogen, but after about seven years they become saturated and cannot be removed and replaced. Glatzmaier developed a method to address the hydrogen problem.

“To try to go in individually and address the situation for each tube is not really practical,” Glatzmaier said. “So, the method that I’ve developed, and what’s in that patent, and what this project has been all about, is to reduce and control the level of hydrogen that’s in the heat transfer fluid.”

NREL applied for a patent on Glatzmaier’s invention in the fall of 2017. The U.S. Patent and Trademark Office last May granted patent protection to what is simply called “Hydrogen sensing and separation.”

Laboratory Filed 188 Patent Applications

Glatzmaier’s patent was merely one of the 40 U.S. patents issued to NREL during fiscal 2020, a bump from the 32 issued during the prior fiscal year. Of the 269 disclosures filed with the laboratory’s Technology Transfer Office as the first step toward either patent or copyright protection, 153 fell in the category of a record of invention and 116 in the area of software.

“We continue to see strong engagement from researchers who submit their ideas for evaluation, with especially strong growth in software,” said Anne Miller, director of NREL’s Technology Transfer Office. “It’s great to see such growth because it tells us that the outreach to the lab to get people to report their innovations and work with us in getting them protected and deployed means that it’s working, that people know who to contact. Hopefully, it means that they have some confidence in our ability to be helpful and steer them in the right direction.”

Anne Miller, director of NREL’s Technology Transfer Office, speaks to laboratory employees at a 2019 event. Photo by Werner Slocum, NREL.

NREL filed 188 patent applications in FY20, up from 124 the year before.

Lance Wheeler, a research scientist at NREL, has about a dozen patent applications in the pipeline tied to the discovery several years ago of a way to turn windows into solar cells. The technology relies on perovskite solar cells that enable the glass to darken and generate electricity, and also switch back to a clear pane. The most recent patent approved, for “Energy-harvesting chromogenic devices,” was granted in November, or almost four years after the provisional application was filed.

“It’s much different than writing a paper because you can write a paper and get it published within months,” said Wheeler, who shares credit on the patent with colleagues Joey Luther, Jeffrey Christians, and Joe Berry. “You’ll never get a patent awarded in months. It’s usually at least a year, and three is not crazy.”

Buildings across the United States account for nearly two-thirds of energy used, so the notion of using these “smart windows” to take advantage of sunlight could bring that energy consumption down.

The patents issued so far for Wheeler’s dynamic photovoltaic windows cover foundational aspects of the technology and sprang from the initial research. A series of patent applications followed.

“When you write the first patent application, you don’t know everything,” Wheeler said. “As you learn more and especially for very particular market needs, or what a product might look like, you learn what’s important and you continue to protect the things that are working. Then you make more discoveries, and you patent more things, but they’re all aligned in the same area.”

Perovskite Composition Earns Patent Protection

Alignment, as it turns out, is a key part of making perovskites most effective in capturing the sun’s energy. Unlike widely used silicon, which is a naturally occurring mineral, perovskites used in solar cells are grown through chemistry. The crystalline structure of perovskites has proven exceptionally efficient at converting sunlight to electricity.

NREL researchers have explored possible combinations for perovskite formulas to find the best. That work resulted in a patent issued in April 2020 for “Oriented perovskite crystals and methods for making the same.” The process begins with a small crystal that’s attached to another crystal and then another and on and on. The crystals are also oriented in the same direction. Kai Zhu, a senior scientist and one of the inventors, uses bricklaying as an analogy.

“You lay one layer down, you put one next to another, you align them perfectly,” he said. “You have to do this in order to build a very large wall. But if you have some randomness in it, your wall will collapse.”

The patent, which covers the composition of the perovskite, was issued to Zhu, Berry, and Donghoe Kim of NREL and to a scientist in Japan. NREL filed the patent application in 2017. Compared to a perovskite solar cell made of crystals allowed to grow randomly instead of in a specific orientation, the NREL-developed composition has been proven to have fewer defects and able to move charge carriers quickly. The result is a perovskite solar cell capable of reaching the highest efficiency.

“This represents the current best performing perovskite composition for the single-junction solar cell,” Zhu said.

Software Filings Reach New Record

NREL’s Technology Transfer Office received 116 software record (SWR) disclosures in fiscal 2020, establishing a new record and marking a big increase from 72 the prior year. The growth in submittals is partly due to more software being developed and authorized for free open-source release. One software record approved for closed-source licensing last year and now available for commercial users is the Electric Vehicle Infrastructure Projection tool, or EVI-Pro. A simplified, open-source version, known as EVI-Pro Lite, also has been released.

The core of EVI-Pro allows users to forecast the demand for electric vehicle charging infrastructure in a particular area. The predictive nature of the software also enables users to determine in advance how an influx of electric vehicles might affect the grid and energy demand. EVI-Pro relies on real-world information.

Eric Wood, the NREL researcher who oversaw the development of EVI-Pro, said it is not enough to simply consider how many charging stations were installed in an area previously and make an educated guess based on that information.

“That misses some key points,” he said. “The vehicle technology is evolving. The charging technology is evolving. And the behavior of individuals that own these vehicles is evolving.”

Early adopters of electric vehicles could charge them at home, in their garage. As the market expands, Wood said, people living in apartments or who have to park on the street need to have a place to plug in.

“The role of public charging infrastructure is going to continue to elevate as the market grows,” he said. “Continuing to develop the software with an eye on reflecting the latest situation in the market is one of the challenges that we face, so keeping EVI-Pro relevant and current is important.”

From the Laboratory to the Outside World

For Glatzmaier, the journey to see how well his invention could perform at isolating and removing hydrogen from the concentrating solar power plant was not a quick one. Grounded from flying because of the pandemic, last year he made four trips to the Nevada site by car. Each trip took about 13 hours one way.

Scientists typically keep close to their laboratory space, with companies able to license ideas that sprang from the inventive minds at NREL. Often, with license in hand, a company will conduct research using its own people. In Glatzmaier’s case, Nevada Solar One signed cooperative research and development agreements that have kept the scientist and company working closely together since 2015.

Glatzmaier initially planned to address the hydrogen buildup using two processes: one to measure the amount of the gas, and a second to extract it. Laboratory-scale tests showed his ideas would work, but he still expected some hesitation from company executives when it came time to trying out the devices on a much larger scale.

“I was thinking, they’re going to be very reluctant because companies tend to not want to make changes to their power plants once they are up and running,” he said. So he proposed installing the mechanism to only measure hydrogen buildup. Instead, the company wanted him to move ahead and tackle both problems at once. From the initial idea to installation has been a long road, but it does not end in Nevada.

Glatzmaier said 80 concentrating solar power plants exist around the world, and talks are in their final stages to license the technology for its use in these plants.

Learn more about licensing NREL-developed technologies.

—Wayne Hicks

Article courtesy of the NREL, The U.S. Department of Energy.