Or Wherever the Sun Shines Brightly
We all know what a PV (photovoltaic) solar panel is, and nowadays there's a good chance you either have some or know someone who does. You may be less familiar with "CSP", or concentrated solar power. Local engineering company Norwich Solar Technologies (NST) deals in both types of solar power, so here's a crash course in what CSP is. Imagine huge fields full of troughs designed to collect and magnify solar energy.
Such a solar field.
The basic structure is akin to a sunbather with a folded sheet of aluminum foil redirecting more sun back to his or her face. Instead of a flat PV panel like on your roof, the rounded CSP trough is a parabola-shaped mirror that concentrates light to a receiver tube. Here's a simple diagram of a parabolic trough in action:
The parabolic trough redirects as much light as possible to a receiver.
The next step in this solar technology is understanding the receiver. It's a glass tube with a liquid core surrounded by an insulating vacuum, just like a thermos filled with coffee. The insulation keeps the heated liquid as hot as possible while it is piped to a heat engine which uses the energy to power machinery or to generate electricity. The process is fairly economical with thermal efficiency ranging between 60% to 80%.
A closeup of a Siemens receiver with an inner core of liquid and outer glass shell.
60% isn't that great, though. Think of it this way, if your parents found out you got a 60% grade on your homework, they'd be less than impressed. The lack of efficiency lies with the receivers, and that's where the local R&D engineering team at Norwich Technologies is focusing its efforts. They recognize the receiver has three problems: one, it's expensive maintaining an adequate vacuum for 30 years in harsh, sun-baked desert climates; two, 360° of the receiver is exposed and therefore suffers high thermal loss despite the outer insulating vacuum layer; and three, the glass tubes are complicated and expensive to manufacture, making them inefficient to operate in lower temperatures due to a lower rate of return.
The R&D engineers are working on a receiver that is more efficient operating at higher temperatures, with a simpler structure making it cheaper to manufacture, and without a vacuum so it is more reliable and reduces thermal loss.
NST works to improve concentrating solar power.
The design improvements include removing the vacuum which allows the air to naturally stratify by temperature based on proximity to the inner heat-transferring fluid. And because there's no vacuum to maintain in harsh desert environments, the tubes are dramatically more durable. Norwich Solar Technologies is also developing an air-stable coating on the receiver which absorbs more sunlight and suffers very little heat loss due to radiation.
Due to pending patents, the specifics of the NST engineers' work is a bit vague here, but the premise is exciting. Local R&D researchers are advancing solar technology typically found in rather distant arid environments. They believe this has the potential to disrupt the global concentrated solar power industry, all from their offices in sometimes sunny downtown White River Junction.