Mark Shortt
Editorial Director
Design-2-Part Magazine

Since coming online in 2007, the Nevada Solar One power plant has symbolized the utility-scale possibilities for concentrated solar power (CSP) generation. The 64-MW solar thermal generating station, located about 32 miles southeast of Las Vegas in Boulder City, Nevada, is reportedly the third largest solar generating station in the world and the biggest solar plant to be built in North America in 17 years. Combining proprietary sun-tracking technology with more than 700 parabolic concentrators and 182,000 mirrors to concentrate the sun's rays, the plant produces enough energy to power more than 14,000 households annually. But it's not just size that distinguishes Nevada Solar One. It's also the first solar thermal power plant to make use of an aluminum space-frame design in its supporting structure, thanks to the pioneering efforts of Acciona SA, Gossamer Space Frames, and Sapa Extrusions' Americas unit (www.sapagroup.com/na ).

Acciona SA (www.acciona.us), the developer and operations lead for the Nevada Solar One project, had been seeking a new way to build solar collector frames--a method that was more cost-effective while permitting easier assembly and greater precision. The company contacted Gossamer Space Frames, the developer of the Organic Connector space frame technology.

"This new technology would allow us to meet [Acciona's] requirements, but only if we had the right supplier," said Gossamer President Glenn Reynolds, in a prepared statement. "We needed an aluminum extrusion partner that had the right circle diameters, could produce in 6061 T6, extrude in a variety of complicated shapes, fabricate to extreme tolerances, and meet just-in-time delivery schedules. Only Sapa's Phoenix operation fit the bill."

By working together, Gossamer (www.gossamersf.com) and Sapa were able to fine-tune the design and manufacturing processes. The result of their collaboration was a tightly toleranced, highly accurate space frame to support the reflective mirrors--a critical function for the success of the overall project.

"Our frames were nearly perfect with no warping," explained Reynolds. "This was critical to the accuracy and efficiency of the solar collectors. When the National Renewable Energy Laboratory came out to check the accuracy of the Nevada Solar One mirror placement, they concluded our frames allowed the mirrors to be 34% more accurate than the nearest competitive design. This translated to an increase in energy production of 4%, or 2.56 megawatts. This was a substantial boost!"

Since providing fabricated aluminum frame components for the Nevada Solar One project, Sapa's Extrusion Americas unit has stepped up its role in manufacturing for this burgeoning industry, culminating in the unit's recent announcement that it has created a dedicated business team "to provide solar equipment makers and solar power-generation companies with expertise in the engineering and fabrication of extruded aluminum components for solar power generation."

The new team, based at Sapa's Phoenix, Arizona, facility, is led by Allan Bennett, recently named vice president, solar market development. Bennett was formerly vice president, sales and marketing, for Sapa's Extrusion Americas West region. The team includes Kwame Yeboah, an engineer with an MBA and a renewable energy specialist with over 10 years of experience in the solar industry, as Sapa's new director of development for solar marketing. It also includes Richard Foote as the new director of program management for the solar group. Foote, who has been with Sapa's Phoenix operation for 20 years in a variety of operational roles, was added-value operations manager for Sapa Phoenix during the Nevada Solar One project. He will lead project execution, including production coordination, project logistics, site support, and inventory management.

"Creating this 'center of competence' allows us to leverage Sapa's physical and intellectual assets to solve solar customers' challenges," said Lynn Brown, senior vice president for Sapa Aluminum North America, in a prepared statement. "We have talented people and valuable organizational experience that qualify Sapa not just as a supplier, but as a true partner to solar field developers, PV panel manufacturers, commercial energy producers, and first-tier suppliers. In addition, we are committed to producing extruded components with high recycled content using Sapa's proprietary remelt technology, so we can deliver an environmentally appropriate product for this environmentally beneficial energy source."

Characteristics such as design flexibility, high strength-to-weight ratio, machinability, and corrosion resistance make extruded aluminum desirable for components and support structures used in utility-scale solar plants, according to Sapa Aluminum. Because of these features, as well as its rigidity, durability, and tight tolerance to spec, extruded aluminum is also said to be well-suited for use in frames and mounts for photovoltaic installations in commercial and residential applications.

The Extrusion Americas unit recently completed a project in which it supplied similar extruded aluminum components to Acciona SA, for a 50-MW solar trough plant in Badajoz, Spain. It's also currently supplying extruded framing for two additional 50-MW facilities in Spain--the Palma del Rio II solar power plant, located in southern Spain, and the Majadas plant in Extremadura, east of Madrid. The extruded aluminum frames, measuring about 26 feet long and 12 feet high, hold parabolic mirrors that work with a computer-controlled system to track the sun. These mirrors focus the sun's rays on a tube filled with heat-transfer fluid. As the liquid heats up, steam is generated to drive a turbine that's connected to a generator to create electricity.

Sapa is manufacturing the support beams, clips, connectors, and other frame components for the solar arrays. The company extrudes the aluminum frames at its Phoenix, Arizona plant and fabricates them at its Guaymas, Mexico, facility.

Design-2-Part Magazine caught up with Sapa's Allan Bennett and Kwame Yeboah to discuss the company's role as a supplier and partner to solar equipment OEMs and power plant developers. Following is an edited transcript of our conversations with them.

D2P: Sapa President and CEO Eivind Reiten was quoted recently as saying that "solar energy is the right way to go for Sapa." He also said that "although solar energy is a relatively new industry, its framework includes several of our key areas of competence and experience, ranging from metallurgy to the industrialization of new technology." It sounds as though the company is very intent on pursuing this market.

Allan Bennett (AB): Absolutely. Sapa has always been a very environmentally conscious company. Our name comes from the hydroelectric power that we were invested in a hundred years ago. It's something that we're very excited about, and it's very visible inside the corporation at all levels.

D2P: What are some of the advantages of using extruded aluminum frames for solar arrays?

AB: Extruded aluminum frames really provide an excellent support system for any kind of a green renewable energy field, because aluminum itself is a fairly green metal. On the average, about 75% of our material has recycled content. Aluminum can be recycled infinitely with no loss in properties, and recycling aluminum takes only 5% of the energy it takes to refine aluminum. So, once you've got it, it takes a very low amount of energy, relatively speaking, to convert it into some other form. Meaning that at the end of the life cycle of these solar projects, 30-50 years down the road, they can take these frames, recycle them for the current metal value, and not lose anything on that. So that's a very good benefit.

It tends to be a good material to make frames out of because it is very lightweight. Depending on the design, it can be extremely quick to assemble, a very important thing when putting together thousands and thousands of frames. The labor can really be a very significant cost. So if we can have a simplified frame that can be assembled quickly, that saves them money in the long run.

D2P: What is it about the extruded aluminum that makes it easy to assemble?

AB: Part of it is that it's lightweight. The pieces can be put up by people without special equipment. The frames that we're making now--it takes about 5 man hours to assemble one frame. We're able to do that extremely quickly. These particular frames are held together virtually 100% with pins, meaning there are no rivets, no bolts. There's a zero fit pin that's put in, it's a friction fit; just stick a pin in there to hold them in place, and they're done. So they go together very quickly and very simply.

D2P: What does the solar power generation industry represent, as a market opportunity, for Sapa Extrusions?

Kwame Yeboah (KY): This is an excellent opportunity, because implementation or application of most of the solar technologies requires a supporting structure. By using extruded aluminum, we are able to play a critical role in reducing the number of components and to really streamline designs in such a way that an entire structure is more cost-effective. For solar thermal projects, we can use unique space frame designs that utilize extruded components quite easily. Prior to Sapa's working with Gossamer and Acciona, most of the technology that was demonstrated for use in solar thermal projects utilized steel. But working with Gossamer, Sapa was able to fabricate and reduce the number of parts and material without compromising either the rigidity or the strength of the structure.  We were able to build a cost-efficient structure that, in the long run, will have a much lower life cycle cost than if steel had been used.

Aluminum extruded components can also be used for photovoltaics (PV). We can build rails, racks, and clips, for roof mounts, or poles, or ground-mount support systems. I would say that extruded aluminum for structural support for the solar industry is technology-neutral, as well as application-independent, so whether it is the residential, commercial/industrial, or utility-scale market application, extruded aluminum systems can play a major part. I would, however, qualify the application-independence, because now, there are some PV structures that you can paste on the roof. Most applications require more robust support structure, though.

D2P: Sapa has stated that "because of tight manufacturing tolerances, and the design and precision of the extrusions, the frames in the Nevada plant are able to focus the mirrors quite precisely on the heat transfer tubes." Can you talk a little about how the tight manufacturing tolerances, as well as the design and precision of the extrusions, all come together to enable precision focusing of the mirrors?

AB: The precision focusing is really a key, because the more accurately the mirrors are focused on the heat transfer tube, the more of the sun's concentrated light hits it, therefore the hotter it gets, the quicker they can move the fluid through, and essentially, the more energy it can generate. So, if it's extremely accurate, they're going to generate more energy than they budgeted for, meaning cash in hand for the owner of the field.

The National Renewable Energy Lab (NREL) took several different frame designs and manufacturers--and this is a combination of Gossamer's design and our precision extrusion--and ours came out as 34% more accurate than our nearest competitor. And that means the 64 MW field in Nevada is actually generating 72 MW.

D2P: Who are your customers in the solar power generation industry--are they OEMs, power project developers, and/or power plant construction firms?

KY: In general, our customers are the power developers or producers, but they could also be OEMs or integrators. In the utility scale market, power developers or producers are our main customers, but their needs vary along evolving business models. Some customers are vertically integrated, build-own-and-operate, or contract developers, so they sometimes bring unique requirements. Presently, we have to look at the utility companies as potential customers because with the passing of the investment tax credits, utility companies may now own, develop, or purchase solar power. So if they choose to develop solar power infrastructure, they will be potential customers.

For the PV market, module manufacturers, vertically integrated companies--like SunEdison, Sun Power, et cetera--are potential customers, and OEM or third-party mounting structure manufacturing companies, such as Unirac, SunLink, et cetera, are as well.
 

D2P: What are their needs--technical, engineering, manufacturing--that you're looking to meet through your custom services?

KY: The needs of our customers vary. In general, our customers desire assistance in engineering support, fine tuning their designs, and provision of downstream value-add services. The scope of customer needs varies from startups to the mature companies. Companies that already have existing designs or drawings generally just request quotations and we custom manufacture the product for them. Those customers developing new products from scratch [will] demand engineering support and help in choosing which alloys to use, tolerances, kitting of products, et cetera--from design through manufacturing to delivery.

D2P: Can you tell us more about Sapa Extrusions' engineering and design assistance services?

AB: We've been able to work with customers to actually lower their costs by using our engineering expertise. We can suggest alloys, we can suggest alterations to the die drawings; we can do multiple things like that to help the end-user out.

We are not structural engineers, we're not design engineers, we're not architectural engineers. But what we've done with multiple customers, not just in the solar industry--is that people will bring their designs to us, and if they involve us early enough in the process, our engineers are able to look at the drawing and suggest changes that will make it more efficient for us to produce and, therefore, at a lower cost to the customer.

D2P: How is your understanding of the technology of benefit to customers who require manufacturing services?  

KY: By liasoning and providing focused service. Being able to speak the language of solar power developers makes it easier to communicate, resolve issues, and assist customers requiring manufacturing services in a timely and more productive way. As the solar marketing director, I'm using my background in the solar industry--my understanding of the technology and the systems--to help Sapa interface effectively with these companies and use our expertise in aluminum manufacturing to mutually come up with new cost-efficient solutions. For instance, every solar developer seems to want a customized structure to support their technology. Since that is a requirement (at least until there is a standardized structure, and I don't see it soon), you need effective communication, in-depth understanding of the solar development process, and the engineering expertise to shepherd a successful project.  Because I understand Sapa's manufacturing capabilities and value-add services, I can work with and help solar developers looking for increased optical efficiency, cost cutting, reliability, and other custom requirements to come out with products or systems that fulfill or exceed their expectations.

D2P: Why do solar developers want a customized structure to support their technology?

KY: It's because they consider the solar field as part of their intellectual property or crucial performance differentiator. Within the same technology classification, there are little nuances, and we know that every minor improvement in the solar field assembly results in increased performance or efficiency of the system and a lowering of the cost.

So you want the frame and the mirror to be designed in such a way as to take maximum advantage of the sun as well as the curvature of your design of your solar field. Customers demand seamless integration between a space frame, or the supporting structure, and the reflectors--the mirrors, the trough, or the dish--to maximize the performance of the solar field.

For instance, on the Acciona project, by designing the space frame seamlessly with the mirror, they were able to actually get 4% additional output. Four percent may not seem significant, but if you calculate the amount of power you get in a year, and project that over the lifespan of that system, it's huge! That's why they want easy-to-assemble components, seamless integration, and rigid structures that can withstand forces including heavy wind loads.

D2P: Why do customers choose your parts or services?

AB: One of the first things is experience. We've been through the learning curve; we know what it takes to manage a project like this. No one else has done one of this size in the last 30 years, and now we're on our fourth one. We feel like we've got this thing down. We can do this, we have the experience.

We also have a wide range of capabilities. With our plant in Mexico and all of our CNC machines and the punches, the drills, everything we have down there, we're very well equipped to handle just about any shape or design that comes our way. In addition, we have two of the larger presses within the Sapa system. We are the only plant within the Sapa System here in North America that has four presses, so we have a pretty good wide range of capabilities here (in Phoenix) as well.

D2P: Has Sapa also manufactured components (frames and mounting systems) for PV solar applications?

AB: We have some. We're just getting into that market really. With my appointment as head of the solar team, we have now turned our focus on the PV segment as well. We're communicating with and working with most of the major players. We have a lot active quotes out there, we have two or three customers--or prospects that have actually become customers--and we're working with several others. It helps that some of the companies coming over from Europe to start up here are already working with Sapa in Europe, so it's a natural evolution for them to come to us.

D2P: What kind of future do you anticipate for the solar power industry--globally and in the U.S.? 

KY: With the renewed momentum and quest for alternative energy, I would say the future is bright. In the long run, the price of fossil fuel is projected to go up. The higher it goes, the stronger the case for solar.

In the U.S., there is over 7,000 GW of solar power potential available in the Southwest. So the supply potential is huge, and will be harnessed to provide a larger percentage of U.S. energy use. Prices for solar collectors or panels will continue to fall because of economies of scale, advancements in manufacturing, and the use of mature manufacturing technology. We see solar being included in the energy portfolio mix of countries with abundant sunshine in the near future. Solar technologies are maturing and would bring a new source of employment and tremendous environmental and economic benefits.

D2P: By extension, what impact do you see this as having on U.S. manufacturing in general, and on Sapa Extrusions in particular?

KY: I think it will be good business for U.S. manufacturers because all these technologies and applications require manufacturing of components. So with increased demand for those products, it's going to result in increased production for manufacturing. I think Sapa, with our integrated Renewable Energy Group, is well positioned to take advantage of the growing demand in manufacturing.

AB: Aluminum extrusions--you're not going to see huge technological advances. What you're going to see with solar collecting technologies, as they advance, is that something's got to hold it together and hold them up. And we're kind of technology-independent, really. We can use our systems for PV mounts, a roof mount, a ground mount, a solar trough, or solar towers. Something's got to hold it all up.

D2P: No matter how the technology advances, there's a need for manufacturing.

AB: Yes. There are things out there that will use less aluminum than current technologies are, but no matter how you look at it, something's got to hold this all together and hold it in place.

Anything you'd like to add?

AB: Just the fact that we have an advantage in that we're flexible enough to add capacity when necessary. We fully expect to be able to meet the demands for these solar projects for many years to come without overextending ourselves. We've proven ourselves already, and we're saying 'bring it on.'

This technical information has been contributed by
Sapa Extrusions North America
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