By Isabel Rodriguez
Hydropower energy harvesters have potential to transform power generation
“Revolutionary” is the word NMSU electrical engineering professor Nadipuram Prasad uses to describe the turbine and generator system he’s developing as a result of his hydropower research.
Dubbed “HyPER harvesters,” the axial-flow flow turbine and generator systems are designed to generate power at any desired frequency from low-head waterways across the U.S. and worldwide.
Prasad and fellow professor Satishkuma Ranade obtained a $299,312 grant from the U.S. Department of Energy to fabricate and test their two 10 kW prototypes in the Elephant Butte Irrigation District.
“The HyPER project is aimed toward developing the cheapest and most efficient ways of harnessing energy from gravity-fed flowing water resources such as rivers, streams, irrigation canals and flood canals,” Prasad said. “The key benefit is that it requires minimal infrastructure for its installation and end use. As such, its use is practically unlimited.”
The hyperboloid shape of the turbine causes fluid forces to transfer energy efficiently onto an impeller, which then converts hydraulic energy into mechanical energy and provides force to rotate the permanent magnet rotor of the generator. The rotating magnetic field induces a potential across the terminals and is transformed to the desired frequency by a back-to-back AC-DC-AC converter.
Prasad described the submarine-type of enclosure that houses the generator as fish-like.
Although we are presently developing a technology with rotating machinery, the concept can be extended to the use of linear generators. “As water enters the inlet and increases in velocity, ‘fins’ and the ‘tail’ located on the submarine can be made to flap back and forth, causing a linear generator to produce electricity” he said. “The HyPER harvester concept is easily adaptable to any fluid-flow system. It can be implemented in urban water supply systems and in wastewater treatment systems.
“Urban water supply systems have a continuous flow of water. The harvester could be used to produce power from large water tanks, which provide sufficient pressure. The process is similar to a natural reservoir draining water into a lower basin.”
While the devices won’t be tested until spring 2014, Prasad said he believes its application could go beyond Elephant Butte.
“The goal would be to integrate hydro plants throughout the distribution system power grid,” he said. “Although we are building a small-scale prototype, it does not hurt to think that someday Hoover Dam and Grand Coulee Dam could be retrofitted with the technology we are developing to produce several hundred megawatts of additional power.
“I would speculate that extremely poor societies who inhabit areas rich in natural flowing water, such as the Mekong River Delta in Vietnam, would benefit the greatest,” he added. “Recent storms such as Hurricane Sandy are good examples of the need to harvest energy. It helps the Federal Emergency Management Agency to maintain sufficient power generating capacity to serve all critical centers.”
“The harvesters have the potential for a simple and economical manufacturing process and the potential for easy deployment,” said Ranade. “I would love to see implementations on small river systems; water delivery systems; and of course in developing nations.”
Prasad described the Drop 8 structure at Elephant Butte as an ideal testing site because it provides sufficient civil infrastructure to implement the test prototypes.
“Drop 8 is an extremely strong structure that offers continuous energy harvesting possibility during the entire irrigation season,” he said. “It’s a historical structure, one we had better not damage, and that’s exactly the type of structure where we want to test the prototypes.”
One challenge concerning the prototypes is ensuring the safety of its material, fiberglass.
The advantage of using fiberglass is that it’s stronger than steel and safer than plastic, Prasad explained.
“It’s important to research the type of material used in water supply systems,” he said. “Chlorinated water will be flowing through the pipes, and we need to know the long-term effects of fiberglass, whether it creates a threat to human safety.
“That’s where researchers with chemical engineering backgrounds are needed.”
The project, Prasad said, has also served as a learning opportunity for several students in his Electric Circuits course for non-electrical engineering students.
“I feel enlightened by the enormous interest it has generated among a large body of students from several engineering disciplines,” he added.
Ranade said he was impressed by “the awesome ingenuity of the students working on the prototype.”
Prasad is currently working to obtain more research grants for the project.
In September 2011, U.S. Department of Energy Secretary Steven Chu and U.S. Department of the Interior Secretary Ken Salazar announced almost $17 million in funding over the next three years for research and development projects to advance hydropower technology.
“This project has come out of a long-term thought process which I never imagined would be put to test,” Prasad said. “I feel like I’ve seen the light at the end of a very long tunnel. I’ve thought about it over the last 20 years, and the U.S. Department of Energy contract is making it happen.
“Electric power is the most critical component of any nation’s infrastructure. The first event at the onset of a hurricane, cyclone or typhoon is the loss of electricity. We must, therefore, think about how to use the energy in the storm, namely wind and water, to protect ourselves.”