SkyFuel, based in the US, is emerging as one of the world’s leading developers of innovative concentrating solar power systems. PEi talks to Randy Gee, chief technology officer and co-founder of SkyFuel, and CSP veteran.

PEi: How do you see the global concentrating solar power (CSP) market developing in next 10-15 years, and in the longer term? Do you expect Spain to continue to be the dominant market?

Randy Gee, co-founder of SkyFuel, believes CSP will be bigger than wind power in the next 10-15 years
Click here to enlarge image

Randy Gee: Right now, CSP is positioned to be the largest means of generating renewable electricity in the 10-15 year timeframe. By the end of that time period I believe CSP will be bigger than wind power. The reason I say this is because CSP systems can provide despatchable electricity, meaning they can deliver the electricity to the utility or customers wherever it is needed by virtue of the fact that CSP is a thermal technology and can therefore can incorporate thermal storage. This is what separates it from wind and photovoltaics.

Looking longer term, I believe it will turn out to be the most important way that renewable electricity will help remedy the global crisis with regard to climate change. I think the cost will come down dramatically as we begin to deploy CSP systems on a large-scale, and ultimately it will be the biggest means of generating electricity for the whole planet.

Right now, Spain is the dominant market and is basically where most alof the activity is currently taking place. However, there are lots of discussions with regard to the US, which is finally beginning to emerge as a big market. Very quickly in the next few years what will happen is the Spanish market will approach saturation and at that point the US will begin to emerge and emergy quickly as a much bigger, longer-term market.

Other markets will also come to the fore. There is a lot of discussions about North Africa, for example, being an emerging market especially for delivering power to Europe. There is also attention on South Africa, as well as a lot of activity taking place in the Middle East. However, throughout the 10-15 year timeframe the US will be the biggest one.

PEi: SkyFuel is emerging as one of the world’s leading developers of CSP systems. Can you tell me about the company?

Gee: SkyFuel is a young company. It has been around for less than two years. And it is only in the last year that has it been focused on the R&D of new CSP technology. What we are focused on as a company, is taking big steps in advancing the technology, but doing it in a very organized and credible way. This approach makes sure that when we come to market with a product it has been thoroughly tested, and therefore there are only have smiles from our customers.

The other thing, in my mind, that is unique about SkyFuel is that we move very quickly. We have that attribute of a small start-up company in that we have a tremendous amount of energy and activity. As a company we highly value the brisk pace of a start-up.

PEi: You designed SkyTrough™, which is described as a ‘breakthrough’ in parabolic trough collector technology. Can you explain why it deserves to be called a breakthrough?

Gee: SkyTrough can be described as a breakthrough because we are using a very different reflective material to what has been used over the last 20 years for the large-scale projects. Up to now all of the systems that have been built in Europe and the US have utilized relatively thick, heavy glass mirrors. And although they are a fine product they are costly. Furthermore, to-date it has only been possible to manufacture these mirrors in Germany, with the associated transportation step the risk of breakage can be high.

SkyFuel is set to unveil its SkyTrough concentrating solar power collector in September
Click here to enlarge image

What we have done is completely changed that approach. Instead of glass mirrors we are using a new material called Reflectech™ mirror film, which is a thin film that can be applied to a variety of substrates, such as sheet metal. It can be curved to whatever shape one desires, it does not break, and therefore it more robust and durable than a glass mirror.

Reflectech mirror film also allows us to move quickly in design changes. Up to now, glass mirrors have only been available in three sizes because of the tooling required to make them is significant.

With the Reflectech approach you can quickly redesign change, modify the size, the length or width, giving much greater design freedom. Thus, it has really changed the design space that can be explored as we improve CSP devices.

PEi: You previously designed the parabolic trough collector for the 64 MW Nevada Solar One in the USA, which began operation last year. What specific knowledge gained from working on that project did you bring to the development of SkyTrough?

Gee: The team that brought that 64 MW project to fruition was a fantastic group of people. It was the first big CSP project in 15 years, so it took a very dedicated group of people to make it a success.

One of the things we had to do was not make major departures from the state-of-the-art that had been developed and demonstrated 15 years earlier. We did made a number of improvements, but we could not make drastic changes relative to what had been in the field before because it would have raised a lot of questions about the project’s viability.

However, one thing that was fundamentally different with the Nevada Solar One project compared to the prior state-of-the-art was that we proved you could do a field-assembled structural space frame in a very accurate, precise and cost effective way. The space frame is the single biggest cost item of a solar field. The idea of doing it in a field assembled way, where you simply put the pieces together one by one in a prescribed way and at the end was assured that it would all fit together in an precise optical way had never been done before.

PEi: I understand that SkyTrough is now ready for commercial deployment. How is the market receiving it?

Gee: With open arms, and there is a great deal of interest in our progress, where we stand and what our next steps are. The first step is the commercial deployment of a small demonstration project, which will be internally funded and based at our R&D facility in Colorado. This is currently under construction and will be completed in September.

The next step after that is a larger, fully commercial operating system, albeit smaller than utility scale, which will give us the confidence to then move onto utility-scale, large-scale deployment.

Of course our customers, such as utilities are anxious that we get through those three steps as quickly as possible, but again we recognize that it is important that we do it in a logical and credible way, so that the market can have full confidence in SkyTrough.

PEi: Parabolic trough technology is one of the most mature of all CSP technologies, so why is there still so much interest in this technology when there are a number of newer technologies, such as dish-Stirling systems or solar chimneys?

Gee: The fact that parabolic trough is mature is exactly what is compelling about this technology. There is a great deal of confidence, and systems of this type have now been operation for 20 years.

A lot of the other emerging technologies are very early in their development. The dish-Sterling systems have some way to go before they will be ready for large-scale commercial use in a reliable way. With the solar chimney concept, again it promising but is very early in its commercialization.

Parabolic trough is well established and is known to work well. There is a great deal of interest from the investment community because parabolic trough is a proven commodity.

PEi: The new project that SkyFuel is working on is the development of the Linear Power Tower, which incorporates linear Fresnel technology. What will set this technology apart from competing solar tower technologies?

Gee: What will be unique about what we do in the linear Fresnel space is that we will be applying Reflectech mirror film to the technology equation. We will be utilizing things other than glass mirrors, which are largely what others are focusing on. We will have more design freedom and space by utilizing ReflectTech in developing what we think will be the optimum solution for a linear Fresnel concentrator.

Randy Gee using a reflectometer to measure the reflectance of the ReflecTech mirror film in commercial use on troughs at the SEGS VI plant in Kramer Junction, California, USA
Click here to enlarge image

When SkyFuels looks at the Linear Power Tower we are applying linear Fresnel at a higher temperature than others in this field. We are looking at using our linear Fresnel device at a temperature that will be in the 500 ºC range, which means we will be using molten salt as the heat transfer fluid. This has the advantage of being a very natural way of providing thermal storage because you use the same medium, i.e. molten salt, in the storage tank as in the solar field. Thus, avoiding the need for heat exchangers in between. It becomes a simpler and more cost effective system, and represents a departure from what others are doing with their linear Fresnel technology.

PEi: The large-scale solar plants that SkyFuel designs can be built as stand-alone power plants or integrated into existing facilities using its proprietary FuelSaver approach. Can you explain what the FuelSaver approach is?

Gee: In a nutshell what we do is take the solar produced steam and use it to supplement the fossil fuel steam that is used in a combined cycle (CC) power plant. It is an addition, supplemental energy stream, which a conventional fossil fuel fired CC plant wouldn’t normally have.

The solar steam is added between the two stages of a traditional CC plant. The first stage being the combustion turbine and the second stage the Rankine cycle turbine. It is a very simple, elegant, and cost-effective way of modifying existing CC plants to incorporate solar.

PEi: In the last 12 months SkyFuel has received a $400 000 grant from the US Department of Energy Solar Energy Technologies Programme and $17 million in financing from a consortium of investors led by Leaf Clean Energy Company. What do these awards mean for SkyFuel, both in the short and longer term?

Gee: It essentially means that we now have all the necessary resources to bring the SkyTrough to full commercialization. We are now fully funded to the point we can bring the SkyTrough into the market.

This is our second round of financing. The first round was a lot smaller, so we have been fairly ‘lean and mean’ in terms of not requiring a huge amount of money to get to the point where we are today. So the $17 million award will take us quite a long way along the progress chart in terms of bringing the SkyTrough to commercialization and also at least initiating and making major steps with our Linear Power Tower approach.

PEi: SkyFuel has technology development partnerships with the National Renewable Energy Laboratory (NREL) and Scandia National Laboratories. How important are these partnership for SkyFuel’s business?

Gee: The national labs have played a really critical role. They have given us access to special measurement tools and techniques that they have developed over the years, as well as a lot of support. Together, this has enabled SkyFuel to move ahead much quicker than it would have otherwise.

Randy Gee was closely involved with the parabolic trough development at the Nevada Solar One site
Click here to enlarge image

Without the support of the national labs, the company would still have moved forward, but it would have been a much slower pace. There is no doubt that they have played an integral part in determining the pace of SkyFuel’s progress.

PEi: Dr David Kearney, who is a widely recognized expert in CSP, was appointed as Senior Technical Advisor earlier this year. What does Dr Kearney’s appointment mean to SkyFuel?

Gee: David brings a lot of additional objectivity to the company. He has been in this industry a long time and has seen it evolve and move forward. He has also been through the times when nothing or very little was happening, so he brings an experienced eye and refined perspective not only to the technology side, but also on the business side. He has seen the ups and downs, and the wide-eyed ideas that never made it to fruition. So in essence it is welcome objectivity that Dave brings to the table.

PEi: In addition to co-founding SkyFuel, you also founded two other solar power businesses. Can you tell me about those companies? Did they play a role in the establishment of SkyFuel?

Gee: One of the two companies I co-founded was Industrial Solar Technology, now part of Abengoa Solar, which specifically looks at commercial andindustrial process heating system opposed to power generation. The other company is Reflectech.

We talked earlier about Reflectech mirror film and I was one of the co-inventors of that technology, along with a scientist at the NREL, so we return to NREL and its help in all this. Now that product, Reflectech mirror film is a key part of SkyFuel, and therefore fundamental to the our business plan.

PEi: Congratulations on becoming a Fellow of the American Solar Energy Society – the American chapter of the International Solar Energy Society. What does this appointment mean to you personally?

Gee: ASES is a great organization. For over 50 years it has stood strong in spreading the word about solar technology. What ASES has been particularly good at is bringing solar researchers and engineers together with the public and with solar businesses, even entry businesses that want to become involved in the solar market place. ASES has been a highly effective organization in bringing interested parties together, and as a consequence it is held in high regard. With this in mind, becoming a fellow of ASES is very satisfying for me.