For those who don't know, I'm at Sandia National Labs for the summer, specifically, at the National Solar Thermal Test Facility (NSTTF) working on dish/engine systems. We also design, prototype, and test parabolic trough and central tower systems.
With industry hoping to go commercial with dish/engine systems in the near future, the bulk of the work is toward reducing the capital and installation costs of the systems. Right now, each stand-alone dish/engine system is only 25kW, so many thousands will be linked up for a utility scale plant. Materials and installation costs add up pretty quickly when you're dealing with several thousands of something.
The optics of the concentrating dish is the first line of offense in the solar thermal game. If you have a crappy concentrating dish that only sort of focuses some of the sunlight onto the engine receiver, you've already shot the efficiency in the foot. These systems have about a 25 foot diameter parabolic mirror dish to concentrate sunlight into an aperture on the stirling engine perched on a steel frame boom at the dish's focal point. It is prohibitively expensive and nonsensical to manufacture 25 ft-diameter mirrored glass, so the parabolic shape is approximated with 40-80 spherical or parabolic (depending on the design) mirrors called 'facets'. Each of these facets has 3 contact points on the underlying steel frame, and each must be adjusted during system installation so that the whole dish optimally concentrates sunlight to the engine receiver. Currently, four engineers take four hours to accurately align all facets in one dish. To help make the dish/engine system a real competitor on the electric power generation market, we hope to bring this down to one to two non-engineers taking 20 minutes per dish. Kind of a tall order, I think.
But, the four of us interns have been hammering away at a quick alignment process and imaging software for only the past 4 weeks, with 6 weeks left to go, and I think we're going to nail it! I've learned a ton about visioning systems, camera optics, and edge detection. This optics stuff is nowhere near my area of "expertise" -- I'd love to work on some heat transfer problems in the engine itself -- but I think it's working out for the best because this work challenges me to learn and think beyond my comfort level. We already have spoken with the company that will manufacture the aligning device (whatever it will look like), and they're looking forward to receiving the software package we develop to work with their product.
Here's a quick intro to the other interns:
Kirill T. (KTrap, K-Money) is a PhD candidate in electrical engineering at Boston University. Originally hails from Ohio, and Russia before that. Has a tendency to lose and forget basic items, such as ID badge and/or bike helmet. Lives one block behind me, practically in my backyard. One of the regular weekend co-adventurers and morning commute bike buddy. Keeps 37.5 days worth of music on an external hard drive protected in a black hiking sock.
Brian M. (BMan, BMonster) is also a PhD candidate, but at the college of Optics (yes, there is a separate college) at University of Arizona in Tuscon. Speaks with a twang that belies his North Cackalacky roots. Plays after-work soccer in a dress shirt, basketball shorts, and hiking boots. Drives the rest of us interns in the official van from the main base to the NSTTF every morning. Has been happily married since the age of 19. Is learning flamenco guitar. Occasional co-adventurer, since he manages PhD work during his hours between Sandia work.
Scott S. (Special Sauce) is a masters student in flow physics at Stanford. A proud Northeasterner who calls Massachusetts, Vermont, and New Hampshire home, he is slowly becoming a California boy. Goes wild for bikes (road, mountain, dirt, and motor) and baseball. The other co-adventurer and occasional morning commute bike buddy. Can hold his own against a large Saggio's pizza and enjoys the simpler tastes in life, like vanilla softserve with rainbow sprinkles. Designed a reed valve while working at a dirt bike engineering company between college and grad school. Speaks Italian.
And now time for a little personal endorsement:
I think solar thermal electricty has a huge potential to provide utility-scale renewable energy in many parts of the United States. Compared to many other countries that already take advantage of the sun for power (Germany) and hot water (China), the US has more solar resource, especially here in the Southwest. Unlike solar photovoltaic systems that rely on complicated materials science, nanotech, and chemical engineering, solar thermal systems use well-developed turbine and engine technologies already used in conventional power plants. Stirling Energy Systems, Inc. -- the company with which we work here at Sandia -- is looking to break ground on the first MWs of their dish/engine systems in a little over a year. So keep your ears to the ground (or eyes to the sky?) for more info.
Engines in operation at the NSTTF:
Two on-sun, and two in stow position:
