Traveling-Wave Hydrokinetic Generator

Traveling-Wave Hydrokinetic Generator

The first project I was involved with at Pliant Energy Systems was the development and testing of a hydrokinetic generator concept using undulating, flexible fins instead of spinning blades. This work was funded by a SBIR grant from the Office of Naval Research, who were seeking a human-portable generator for expeditionary power, along with a grant from NYSERDA for early-stage renewable energy technology prototype development.

Pliant Energy Systems' prototype traveling-wave hydrokinetic generator

The video above shows a tow-tank test of a four-finned prototype generator at Stevens Institute of Technology's Davidson Lab. I was responsible for much of the electromechanical design and performance characterization for this prototype. I designed the 3D printed white "vertebrae" along the device's spine. A subset of these contain power-take-off units of my design that convert the fin's reciprocating rotation into DC electrical power.

I characterized the power-take-off units' mechanical-to-electrical conversion efficiency into a range of electrical loads using voltage, current, torque and speed measurements. I set up the acquisition systems and designed the experiments for towed power performance testing, and analyzed the power performance results.

This test shows the culmination of a series of iterative design and test cycles of the traveling-wave generator concept. Along the way, I was involved in theoretical power performance characterization, prototyping of other power-take-off systems using dielectric elastomers for a totally soft machine, materials selection and testing for the flexible fins, and the development of enhanced in-house computational geometry software tools for the design of the generator's fins.

For the test pictured here, the hydrodynamic thrust force on the generator was measured using the load cells built into the Davidson Lab's towing rig. Earlier prototype tests during the project were conducted a flume at Alden Laboratories in Massachusetts, and I designed and constructed a thrust-measuring frame and portable acquisition system for those tests.

Traveling-Wave Hydrokinetic Pump

The last project I worked on at Pliant was also a hydrokinetic project. We secured a $200k Department of Energy Phase I SBIR to execute a proof-of concept prototype for a completely mechanical self-powered hydrokinetic pump shown below.

Pliant Energy Systems' prototype traveling-wave hydrokinetic pump

You can read more about the traveling-wave hydrokinetic generator and pumping concepts on Pliant's website. The small team's R&D focus shifted toward using the same undulating fins for robotic propulsion, and many of the years I worked at Pliant were focused on that robotic development. However, the energy harvesting applications remain on the table as targets for commercialization as well as interesting possibilities for persistent robotic presence in areas where strong currents could be tapped for recharging.