Q&A: Scott Potter (Engineering a Way To Clean Solar Mirrors)

Designer and technology executive Scott Potter won first prize in the 2012 RL78 Green Energy Challenge, presented by Renesas Electronics in partnership with Circuit Cellar and Elektor magazines. The global contest called on participants to develop green energy designs utilizing Renesas’s RL78 microcontrollers. Scott won with his solar-powered electrostatic cleaning robot, which removes dust and debris from the tracking mirrors of large-scale concentrating solar power plants.—Mary Wilson, Managing Editor

Scott Potter

MARY: Where do you live and what is your current occupation?

SCOTT: I live in Los Gatos, CA, and I’m a senior director at Jasper Wireless, a company providing machine-to-machine (M2M) data communications services. I have been with Jasper since the beginning in 2005 when the company started with four people and a plan. Now Jasper is approaching 150 employees and we are a global company. I have served many roles at Jasper, working on location technology, device middleware, back-end reporting, and front-end software.

My other job is as an inventor at Taft Instruments. We are just now forming around the technology I developed for the RL78 design challenge. We are finding there is a big need for this solution in the solar industry, which is poised for tremendous growth in the next few years.

MARY: How did you first become interested in embedded electrical design? What is your educational background?

SCOTT: I started working for my father at his startup in the basement of our home in Long Island when I was a teenager (child labor laws were more lax back then). We were doing embedded electronics design along with mechanical modeling and prototyping. I learned from the best and it has stuck with me all these years. I went on to get a BSEE from Tufts University and I toyed with the idea of business school, but it never gripped me like engineering.

MARY: Why did you enter the 2012 Renesas RL78 Green Energy Challenge? What about its focus appealed to you?

SCOTT: The green energy design challenge came along at the perfect time. I had been working on the cleaning robot for a few months when I saw the challenge. The microcontroller I had originally picked was turning out to be not a great choice, and the challenge made me take a look at the RL78. The part was perfect, and the challenge gave me a goal to work toward.

MARY: How did the idea of designing a robot to clean solar-tracking mirrors (i.e., heliostats) for solar power plants come to you?

SCOTT: I can’t say it came to me all at once. I have participated in solar technology development sporadically throughout my career, and I have always tried to stay abreast of the latest developments. After the lessons learned from the parabolic trough concentrators, the move to high-concentration concentrating solar power (CSP) plants, which more efficiently convert solar power to electrical power, struck me as the right thing to do.

The high-concentration CSP plant utilizes hundreds of thousands of mirrors spread over many acres. The mirrors reflect sunlight onto a centrally located tower, which creates intense heat that drives a steam turbine generator.

The efficiency gains from the higher temperatures will make this the dominant technology for utility scale power generation. But there is a high maintenance cost associated with all of those mirror surfaces, especially in environments where water is scarce. A number of people have realized this and proposed various solutions to keeping the surfaces clean. Unfortunately, none of the proposed solutions will work well at the scale of a large utility plant.

I experimented with quite a few waterless cleaning techniques before coming back to electrostatics. It was my wife, Dia, who reminded me that NASA had been cleaning dust off panels on space missions for years using electrostatic principles. She convinced me to stop working with the forced-air concept I was doing at the time and switch to electrostatics. It was definitely the right choice.

MARY: What does the system do? What problems does it solve for power plants? How is the device different from what is already available for the task of cleaning heliostats?

SCOTT: Our patent-pending device is unique in many ways. It is completely autonomous, requiring no external power or water. The installation time is less than 10 s per heliostat, after which the device will remain attached and operating maintenance free for the life of the plant. We borrowed a marketing term from the military for this: “Set it and forget it.”

Most of the competing products have a long installation time and require some external wiring and maintenance. These can be logistical problems in a field of hundreds of thousands of mirrors.

Our device is also unique in that it cleans continuously. This prevents accumulation of organic materials on the surface, which can mix with dew and make a bio-film on the surface. That film bakes on and requires vigorous scrubbing to remove. We also have a feature to handle the dew, or frost, if it’s present.

MARY: What were some of your design challenges along the way and how did you address them?

SCOTT: They were numerous. The first challenge was the power source. It is important that this device be entirely self-powered to avoid having to install any wiring. I had to find a solar-panel configuration that provided enough power at the right voltage levels. I started with lower voltages and had a lot of trouble with the boost converters.

I also couldn’t use any battery storage because of the life requirement. This means that everything has to operate intermittently, gracefully shutting down when the sun fades and then coming up where it left off when the sun returns.

The next challenge was the mechanical drive. This had to grip the mirror tightly enough to resist a stream of water from a cleaning hose (infrequent cleaning with water will probably still be performed). And it had to do this with no power applied.

Another big challenge was the high-voltage electronics. It turns out there is little off-the-shelf technology available for the kind of high-voltage circuitry I needed. Large line output power transformers (LOPTs) for old cathode ray tubes (CRTs) are too large and expensive.

Some of the resonant high-voltage circuits used for cold cathode fluorescent lighting (CCFL) can be used as building blocks, but I had to come up with quite a few innovations to be able to control this voltage to perform the cleaning task. I had more than a few scorched breadboards before arriving at the current design, which is very small, light, and powerful.

MARY: You recently formed Taft Instruments (click here for Taft website). Who are the players in the company and what services does it provide?

SCOTT: We formed Taft instruments to commercialize this cleaning technology. We have been very fortunate to attract a very talented team that has made tremendous progress promoting the company in industry and attracting investment.

We have Steve Gluck and Gary Valinoti, both highly respected Wall Street executives who have galvanized the company and provided opportunities I could never have imagined. They are now recruiting the rest of the team and we are talking to some extremely qualified people. And of course my wife, Dia, is making numerous contributions that she will probably never get credit for.

MARY: How’s business? How would you describe the market for your product and the potential for growth and reach (both domestically and globally)?

SCOTT: We are not at the commercial deployment stage just yet. Our immediate focus is on the field trials we are starting with a number of industry players and the US Department of Energy National Laboratories. We fully expect the trials to be successful and for our large-scale rollouts to begin in about a year.

The market potential for this is tremendous. I’m not sure anyone fully realizes yet the global transformation that is about to take place. Now that the “grid parity” point is near (the point where the cost of solar power is competitive with fossil fuels), solar will become one of the fastest-growing markets we have seen in a century.

Entire national energy pictures will change from single-digit percentages to being dominated by solar. It is a very exciting time in the solar industry, and we are very happy to be part of it.

MARY: Are you individually—or is your company—developing any new designs? If so, can you tell us something about them?

SCOTT: Yes. I can’t say much, but we are working on some very interesting new technologies that will improve on the electrostatic cleaning principles. This technology will vastly expand the base that we can work with.

MARY: You describe yourself as a “serial entrepreneur” with a strong technical background in electronics, software, hardware, and systems design. That combination of skills comes in handy when establishing a new business. But it also helped you land your day job eight years ago as Director of Location Technology at Jasper Wireless. What do you see as future key trends in M2M communications?

SCOTT: M2M has really taken off since we began in 2005. Back then, there were only a few applications people had envisioned taking wireless. That list has exploded, and some analysts are predicting volumes of M2M endpoints that exceed the human population by tenfold!

We have seen large growth in a number of different verticals over the years, the most apparent one right now being automotive, with all the car companies providing connected services. Jasper is uniquely positioned to offer a global solution to these companies through our carrier partners.

MARY: Over the years, you have gained expertise in areas ranging from embedded electronics and wireless, to applications of the global positioning and geographic information systems (GPS and GIS). What do you enjoy most and what are some career highlights? Is one your involvement in the development of a GPS for the New York fire department’s recovery operations after the collapse of the World Trade Center?

SCOTT: What I enjoy most is working with motivated teams to create compelling products and services. One of my proudest moments was when our team at Links Point rose to the 9/11 challenge. At the time, I was a founder and the chief technology officer of Links Point, which provided GPS and location mapping.

When the request came from the New York fire department for a solution to locating remains at the recovery site, the team dedicated themselves to providing a solution no first responder had ever had access to previously. And we did that in record time. We had to come up with a proposal in a half-day and implement it within three days. You have to realize that GPS and PDAs were very new at the time and there were a lot of technical challenges. We also had to compete with some other companies that were proposing more accurate surveying equipment, such as laser ranging.

Our product, a PDA with a GPS attachment, won out in the end. The advantages of our handheld devices were that they were rugged and that firefighters could easily carry them into Ground Zero. We got the opportunity and honor of serving the  FDNY because of the extreme talent, dedication, and professionalism of my team. I would like to mention them: Jerry Kochman, Bill Campbell, Murray Levine, Dave Mooney, and Lucas Hjelle.

MARY: What is the most important piece of advice you would give to someone trying to make a marketable product of his or her design for an electrical device?

SCOTT: Whatever the device, make sure you are passionate about it and committed to seeing it come through. There is a quote that Dia framed for me hanging in my lab—this is attributed to Goethe, but there is some question about that. Anyway, the quote is very inspirational:

“Until one is committed, there is hesitancy, the chance to draw back. Concerning all acts of initiative (and creation), there is one elementary truth that ignorance of which kills countless ideas and splendid plans: that the moment one definitely commits oneself, then Providence moves too. All sorts of things occur to help one that would never otherwise have occurred. A whole stream of events issues from the decision, raising in one’s favor all manner of unforeseen incidents and meetings and material assistance, which no man could have dreamed would have come his way. Whatever you can do, or dream you can do, begin it. Boldness has genius, power, and magic in it. Begin it now.” I

Editor’s note: For more details, schematics, and a video of Scott Potter’s solar-powered electrostatic cleaning robot, click here.

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