in 1992 by Shawn Lawlor, who learned about ramjet engine principles while studying aeronautics and astronautics in bachelor’s and masters programs at the University of Washington. The concept is pretty simple. Supersonic airplanes like F-18 fighter jets create shock waves that, with a little clever engineering using air inlet structures that have been around for decades, can be used to tightly compress the air as it passes into the engine, allowing for more efficient combustion of the jet fuel, and therefore, a more efficient engine. “You get more pop out of the fuel if it’s mixed with highly compressed air,” Jewett says.
So what does this have to do with coal-fired power plants, which aren’t designed to hurtle through the air at Mach 2? Lawlor wondered if there was a way to design inlets that could perform this function in a stationary environment by spinning discs, at tremendous speeds like Mach 2 and above, harnessing the resulting shock waves so that they could compress a lot of air. This could then lead to significant energy and compressor efficiency gains for industrial customers.
The company raised $2 million in angel funding in its first five years, and got its first patents on rotating supersonic compression. Jewett, a former Seattle City Attorney, entered the picture as an angel investor in 1998 and was soon installed as president and CEO. But the company’s initial application, for making a 10 Megawatt engine for electric power generation, ran out of money during the Enron-led energy crisis in 2001, and the subsequent economic downturn following that year’s terrorist attacks, Jewett says.
Ramgen bounced back in 2002 with private funding and support from the U.S. Department of Energy to develop an air compressor. Then in 2005, it won a design competition sponsored by the DOE that committed $11 million over four years. The Department of Energy told the company that it would like to focus on developing its ramjet shock wave technology to compress air, and more specifically the carbon dioxide part, because it’s one of the critical steps needed as part of a larger strategy for carbon capture and storage, Jewett says.
So how does it compare with the existing paradigm for industrial air compression, and how is Ramgen’s technology really different? Jewett had to step up to the white board to answer that.
Industrial centrifugal air compressors that do all sorts of things—everything from running power tools in automated factories to the manufacture of computer chips—aren’t really set up to handle shock waves that result when blades spin faster than the speed of sound, about 700 miles per hour. The waves actually disrupt their compression, so these machines have to run their blades below the speed of sound, Jewett says.
But at the slower speeds, these machines can only achieve about 3-to-1 levels of compression, while generating a lot of extra heat—an increase of as much as 200 degrees Fahrenheit. To get rid of that waste heat, the air has to run through a water-fed cooling apparatus, on its way to another compression chamber, and then another intercooling step, for each attempt to compress air further, Jewett says. To really compress air tightly, several steps of compression and cooling are required.
By comparison, the Ramgen system is designed to take the regular air we breathe
