Initially designed for use on the Moon, the Electro-Hydraulic Fracturing system — developed at Auburn University with NASA funding — relies upon short, high-pulse power created by ultra-high capacitors. Two electrodes featuring a high voltage difference are placed in a small amount of non-toxic liquid — an ounce of water, for example. After the proprietary probe is placed in a drilled hole within concrete or rock, a very rapid release of high-voltage electrical energy, stored in the capacitors, is discharged. The liquid provides the spark between electrodes, resulting in a high-temperature containable “plasma ball.” The ping-pong-ball-sized bead creates a shock wave with pressures that exceed the material’s compressive strength, causing a fracture.
Because the system is electrically sourced, users can control the energy “on-the-fly” to provide precision-controlled fractures, according to Frank Magnotti, Chief Executive Officer of Petram Technologies, the Cambridge, MA-based company prepared to commercialize the technology. By engineering the electrodes, liquid, and discharge strength, users can create specific breaks to match the material and surrounding constraints.
“You can dial up the intensity of the plasma ball to fracture greater pieces or smaller pieces, or just precisely crack the structure,” said Magnotti. The company has increased the performance of the probe threefold, presently yielding up to 3 cubic yards per “blast” — the quotation marks used by Magnotti to emphasize the quieter approach to demolition.
The Electro-Hydraulic Fracturing idea originally came about almost a decade ago as NASA brainstormed different ways to mine the resources of the Moon — a low-gravity environment where traditional explosives are unlikely to work. NASA also required an alternative to carrying a load of explosives, jackhammers, and combustible chemicals on the lengthy trip through space.
As a result, NASA funded a project with Auburn University to develop an alternative. Petram Technologies acquired the exclusive rights to the university’s patented electrical-probe technology, and expanded its use to include demolition and construction applications on Earth.
With the rapid release of the capacitor’s high-voltage electrical energy, the Electro-Hydraulic Fracturing probe is designed to operate more quickly than conventional, chemically driven explosive blasts — an advantage for workers trying to avoid bursts of noise and debris, said Steve Best, one of the Auburn patent-holders. “This allows us to virtually eliminate fly-rock, noise, and seismic vibrations,” Best said.
Because the approach is a quieter, more precise form of fracturing, the system potentially provides new efficiency benefits in the construction field. In urban foundation demolition, for example, the technology’s muted operation could allow crews to work at night and dramatically speed up project timelines.
“The noise levels are practically nonexistent,” said Magnotti. “It’s not like jackhammering a road. You could actually have demolition projects at night, near hospitals.” Also, being electrically driven, the technology does not require the chemicals and gas byproducts inherent with chemical blasting.
While initial applications for Electro-Hydraulic Fracturing were planned for mining and roadway construction, Magnotti and his team see more financial opportunity in precision, or “surgical” demolition, including compressor concrete foundation demolition — a space-constrained effort that compacts the soil around concrete pilings.
Petram has replicated Auburn’s previous lab testing setup in its Notasulga, Alabama test facility. Enhancements include a large water tank facility with hydrophones to characterize the plasma-blasting shock waves created. The Petram team also made a new simulation model to analyze the effects of simultaneous blasts and the effects of hole depth on crack size.
The company’s first commercial product, scheduled for release in February, is trailer-mounted for multiple field applications.