By Mike Janes
Sandia researchers have designed and demonstrated key features of a hydrogen storage system that uses a complex metal hydride material known as sodium alanate. The system, developed through a multiyear project funded by General Motors, stores three kilograms of hydrogen, making it large enough to evaluate control strategies suitable for use in vehicle applications.
The design tools developed by Sandia researchers now provide GM with a workable template for future designs, which is expected to significantly save the company costs and time when developing hydrogen storage systems for onboard vehicular applications.
“For GM, the enduring value of this project can be found in the design concepts, computational tools, and control strategies that Sandia developed,” says Jim Spearot, GM lead executive for hydrogen storage. “With this new body of knowledge and information, we will be able to quickly design viable systems as new storage materials emerge.”
Methods have been validated
Sandia researchers are quick to point out that the system was not meant to fit on board a vehicle, and that sodium alanate will not be the material of choice for onboard storage of hydrogen. But, although it is indeed larger and heavier than a viable automotive storage system requires, the system’s engineered elements address many of the thermal management issues necessary for successful vehicular storage of hydrogen.
“We’ve shown that we can engineer vehicle-scale energy storage systems to meet a variety of operating requirements and driving cycles, and our design methods have been validated for relevant materials,” says Terry Johnson (8365).
Terry says Sandia is well-equipped to do similar work on behalf of other companies, including those that manufacture rolling stock, specialty, or heavy-duty vehicles. Companies that focus on other niche applications, including underwater, military, or unmanned aerial vehicles, would likely benefit from Sandia’s expertise, too, he says.
Modular heat exchange system
In addition to its storage capacity, the unique features of the Sandia system include an advanced heating system whereby a fraction of the stored hydrogen is used to provide heat to release the remaining hydrogen. This method — the catalytic combustion of hydrogen — is not new, Terry says, but is unique to this particular application and the first to be successfully demonstrated. “We chose not to use resistive [electrically driven] heating, because it would have necessarily resulted in a larger and heavier system,” he says.
After considering a number of thermal management options, Sandia selected a “shell-and-tube” heat exchanger, a heating technique common in many industrial processes. The “SmartBed” — a term coined by Sandia that refers to the method for controlling a modular storage system — consists of four identical modules, each of which contains a shell-and-tube heat exchanger. The material used to store the hydrogen — sodium alanate — resides within the tubes, which essentially serve as a high-pressure storage vessel. Inside the shell, a heating fluid circulates to transfer heat to and from the sodium alanate.
The modular design of the system means that only a minimum amount of the storage material needs to be heated at any one time. The design also aids in packaging the system to fit on board a vehicle.
Sandia’s work with GM on a hydrogen storage system reflects the Labs’ long history of exploring basic and applied science for energy and transportation. From developing renewable means of producing hydrogen, to discovering the science behind hydrogen safety, to creating the building blocks of hydrogen and fuel cell systems, Sandia scientists and engineers are actively working to help hydrogen and fuel cells take their place in a sustainable energy future.
-- Mike Janes
There’s a new supercomputer being born at Sandia, and it will stand on the shoulders of giants. But it will also be a more democratic supercomputer: of Sandia, by Sandia, and for all Sandians. Red Sky, now being assembled in the space where legendary system ASCI Red once stood, will replace Thunderbird, which currently serves as Sandia’s “everyday” computer.
Red Sky will deliver more than 160 tera-flops peak performance and will provide roughly three times the computing capacity of Thunderbird. Red Sky is designed to be expanded economically to several times this initial capacity to meet future growth in demand. That’s important because in-house requests for institutional computing cycles currently outpace supply by a factor of four.
“One thing that’s really exciting to me about this project,” says Rob Leland, director of Computing and Network Services Center 9300, “is that we’re taking the architectural philosophy and design principles that we pioneered in systems for the weapons program such as ASCI Red and Red Storm and building a machine that will be broadly available to the entire Laboratory.”
Rob says Red Sky is intended to be a capacity machine (intended to support a large number of small and medium-sized jobs) but to be much more scalable, (allowing larger, more complex jobs to be run) than typical commercially provided capacity systems. The trick, Rob says, is to leverage the economics of commodity parts and yet incorporate the design principles learned from previous generations of specialized high-performance computing systems.
The use of “red” in the name is meant to evoke the successful supercomputing systems and programs of Sandia’s past. The designers and builders of Red Sky built on the design principles and successes of earlier machines such as ASCI Red from the mid-1990s and Red Storm from early 2000.
“We use ‘red’ in the name to convey that we intend to deliver a very high-caliber system to the user community at Sandia,” Rob says. “It’s also intended to convey to the broader computing community that this is a machine consistent in its approach and its philosophy with those previous machines that were so highly regarded. We’re trying to create that continuity and that sense of legacy.”
Red Sky will be more than just a capacity machine. “It’s a scalable design,” Rob says, “which means that application codes can run very efficiently using lots of processors on the system. But it’s also an extensible machine, meaning we can physically build it out. We can add more computing power to it in an efficient way that doesn’t require us to rework the machine.”
Rob says that in a more typical machine designers have to add a whole bunch of infrastructure to it in a nonlinear way to improve performance.
“Normally,” Rob says, “if you doubled the size of the machine, for example, you’d need four times as much cabling. That’s not true here because the machine is very replicable and very extensible.”
One key feature that enables physically extending the machine is the simple “topology” used, Rob says, meaning that things are connected in a three-dimensional mesh-type grid.
“It turns out,” Rob says “that structure is a good choice for mapping physical codes onto the machine because physics is typically expressed mathematically in a three-dimensional grid that matches well to the machine.”
A project of this complexity and ambition requires a close partnership with leading-edge vendors. In this case, Sandia worked with Sun Microsystems and Intel.
“Sun was willing to take substantial risks and create and invest in technology for the partnership,” Rob says, “so it was a very good fit for our needs and goals.” Sun was also willing to work with Sandia to innovate in several key dimensions, he says.
“Intel gave us early access to their latest processing technology and very competitive pricing for that new technology,” Rob says. Intel was a natural choice because it has been very actively reestablishing itself in the scientific high-performance computing market in recent years. Rob says Intel’s processor technology is moving intentionally toward incorporating certain key technologies and design features that support Sandia’s goals for the machine.
The Red Sky project, Rob notes, required both a commitment to strong technical innovation and strong value because the machine must provide the highest-quality service for the lowest prices possible. The Labs also wanted the project to continue Sandia’s legacy of innovation and excellence in high-performance computing and leadership in the field.
Red Sky is expected to be online in full production service later this year. -- Stephanie Holinka
Sensors placed on Sandia research turbines in Bushland, Texas, are providing researchers from the Labs and Purdue University enhanced capabilities to monitor and control wind turbines.
A team from both institutions presented research on the topic in a paper at the Windpower 2009 Conference and Exhibition in Chicago in early May.
“Excessive loads on wind turbines can cause damage to components, which can then lead to costly repairs or even catastrophic failure in some circumstances,” says Josh Paquette (6333), one of the Sandia engineers who worked on the project. “We are investigating how an accelerometer system can help determine blade motions and structural health, and allow for operational modifications to avoid damage.”
The accelerometer systems consist of sensors and software that constantly monitor forces exerted on wind turbine blades. They measure two types of acceleration: those due to varying winds and those caused by gravity and rotation. It is essential to accurately measure and separate both sources of acceleration to estimate forces exerted on the blades.
Purdue is under contract with Sandia to help develop the technology. In this particular research relationship, the two institutions are collaborating on an experiment using these sensors to monitor turbines in real time. The goal is to determine how the blades were actually being loaded and then eventually feed that information into a turbine’s control system.
The sensor research, says Jose Zayas, manager of Wind Energy Technology Dept. 6333, has been conducted on subscale experimental-size blades. The results will then be extrapolated to full-size machines.
“This work is important because as more wind power is deployed, it is essential to continue to develop innovations that improve the technology and protect the capital investments,” Jose says. “Each utility-scale machine costs in the range of $2 million to $4 million and damaged components could lead to the loss of entire machines.”
Wind power is becoming a more prevalent part of the US energy portfolio, Jose notes. At the end of 2008 some 25 gigawatts of wind energy had been installed nationwide. Also, in 2008 — for the second year in a row — wind energy accounted for approximately 40 percent of all new energy installed in the US.
A wind turbine’s major components include rotor blades, a gearbox, and generator. The wind turbine blades are made primarily of fiberglass and balsa wood or foam, and occasionally are strengthened with carbon fiber.
“The aim is to operate the generator and the turbine in the most efficient way, but this is difficult because wind speeds fluctuate,” says Doug Adams, a professor of mechanical engineering and director of Purdue’s Center for Systems Integrity. “You want to be able to control the generator or the pitch of the blades to optimize energy capture by reducing forces on the components in the wind turbine during low winds. In addition to improving efficiency, this should help improve reliability.”
Jose calls the joint research between Sandia and Purdue “a perfect partnership between a national laboratory and an academic institution.
“It shows how the two can work together and collaborate to improve industry,” he says.-- Chris Burroughs