It’s been 4 years since we commissioned our solar electric kitchen, and shut down the giant ground-based mirrors that launched BjornQorn. For the past ten years, solar electric has absolutely plummeted in price. This is great news for the world! Solar electricity is now broadly competitive in the marketplace with electricity from other sources. Just about every business should be investing in solar power. With almost zero maintenance, we have been able to generate significantly more power than our kitchen uses each year. Our ground-based mirror experiments have continued on the side, but have been mostly frustrating for the past few years. We’d been trying a modification of the original design but hadn’t been able to get it to work. We were almost ready to hang up our inventor’s spurs, and lay the solar basin project to rest. After all, why continue to pursue it with solar electric so cheap?
Solar electric may be the right answer for our American business, but it is still not nearly affordable for everyone everywhere. The solar basin will still come in 5x-10x cheaper per watt, which makes it accessible to a much broader swath of the world. A solar basin can also be operated completely off-grid without expensive and perishable batteries. The materials that need to be imported are minimal and can ship rolled up. Our end game has always been to create something that could be used by small food businesses in the developing world, but the basins we began BjornQorn with weren’t easy enough to build and operate, and didn’t last long enough.
This summer, we’ve had a bit of a breakthrough, and gotten the new trough-style solar basin to work. The crux of the new idea is still the same: the dish geometry can be built directly into the ground. This allows the use of dirt cheap materials, since it is literally made of dirt. But the trough solves a lot of problems with the original design. Here’s a list of some of the original basin problems, and the way the trough solves the problem:
Large holes required heavy equipment to dig
With the trough the excavation scales linearly, instead of the square of power output, so the holes are much more manageable to dig at a commercial scale.
Cooking surface was difficult to access
The cooking receiver is a long level tube with the trough design, which can always be easily accessed.
Deep Basins were hard to drain
The trough design is much shallower than the original basin for a given power, making it much easier to create a passive drain in most locations.
Surface deteriorated rapidly
The 2 dimensional curvature of the trough allows the use of a much more robust professional reflective film on a thin metal substrate, making it much more durable, with a quoted lifespan of 25 years.
Low winter sun angles and snow cover
Don’t build basins in the northeast! This is a design for equatorial regions.
solar roasted coffee
boiling water to test power
These pictures and video are from the first successful small scale test. The next step is to go back to a commercial scale prototype. We're targeting 10 Kilowatts, about 15 times the size of this test. We'll be blogging about it as we get underway.
infrared image of oven interior
ambient oven temperatures in the 400s F, surface temperatures in the 500s
some test popcorn popping