Humans have looked to moving bodies of water to generate energy for centuries, but interest in this form of power generation has ebbed and flowed over time.
In the past half decade, the level of interest in the sector has risen as policymakers rifle through portfolios of research ideas for their potential contributions to the goal of freeing the nation from its dependence on foreign oil.
One of the specific areas that the Department of Energy has been financing is
the field of hydrokinetics.
Hydrokinetic power makes use of submerged turbines in rivers, estuaries and
even the ocean to generate energy over time.
Helical turbines are the predominant means to capture “tidal energy,” while moveable arms fixed to underwater platforms are in trial to capture vertical “wave
energy.”
Currently, the Department of Energy has a mandate to spend $50 million
a year on backing such research. For its part, the Federal Energy Regulatory Commission has approved 72 permits for pilot projects over the past two years , according to its records.
Ocean Renewable Energy Power Company, LLC , which has plans to build the largest ocean-based system in the U.S., is one of the companies that has won such funding.
The company has claimed a $10 million grant from the DOE, and has raised an added $20 million in funding, mostly from undisclosed sources.
After obtaining a preliminary permit for its pilot efforts, Ocean Renewable has applied for a full license from FERC to build a commercial hydrokinetic turbine system at Cobscook Bay, Maine near the Bay of Fundy, a site that yields a roaring 4.66 knots of tidal force.
President and CEO Chris Sauer says granted the approval, his company will move swiftly toward installation of a commercial system, which would tie into a regional power grid.
The company says its technology is proven after a year-long demonstration project.
However, the company declined a request to view its data, saying the amounts of sheer data were “staggering” and “not in publishable form.”
“We’ve gleaned from it what we need and are now totally focused on our grid-connected project that we hope to install by the end of the year,” Sauer said.
Virtually all hydrokinetic turbines resemble giant manual lawnmowers, a design patented by Alexander Gorlov of Northeastern University in 2001.
Sauer calls what his company uses an “advance cross-flow” model, and he says each of his 150 kilowatt units could power 50 to 75 homes.
However, power speaks to the concept of capacity and is measured in kilowatts or megawatts, while energy is a different concept which pegs the power against time, in terms of kilowatt hours.
The company plans to install one of its 150 kilowatt turbines this year, and four next year, anchoring them near the floor of the bay, and progressively build out to 3.2 megawatts by 2014. The system would tie into Bangor Hydro Electric Co. grid.
Successful installation of the project would inaugurate ocean power as an option in this region, where winds and brackish tidal currents are strongest on the east coast.
It would at the same time provide a much needed validation for an industry that is conflicted internally about its abilities to pass through the “valley of death,” a concept investors use to denote the gap between wistful potential and actual delivery on investment.
Hydrokinetics have faced numerous obstacles at places like the Piscataqua River estuary at Portsmouth, N.H., where Underwater Electric Kite Corp. and Oceana Energy Co. withdrew FERC permits in 2009 after public and academic concerns the turbines would obstruct shipping lanes and impact a historically delicate environment.
Another company, Verdant Power, is continuing to pursue build out of a 300-turbine system in the East River at New York City but has faced significant challenges, reclaiming installed turbines that had broken components after months of operation.
Martin Wosnik, a member of the University of New Hampshire’s Center for Ocean Renewable Energy, is testing a turbine from Indiana-based Lucid Energy Technologies, under the General Sullivan Bridge at Dover, N.H.
He said hydrokinetics is 20 years behind wind energy with unique challenges of a hostile environment in the saline waters of estuaries. Water is 850 times denser than air.
Turbines that are operating in estuaries must endure slack water time in-between tides when currents subside, and operate under high stress in spring tides (the highest tide patterns) and neap tides (the lowest tide patterns.) Each month, due to lunar cycles, there are two spring tides and two neap tides.
A competitor to Ocean Renewable is a firm called Tidewater Associates.
The company attained a permit in December to assess the impacts of a proposed $42 million tidal barrage system, which involve a 1,200 foot composite wall along Half-Moon Cove near the Bay of Fundy. The project includes gates and helical turbines to generate energy.
Company founder Norman Laberge says his project would provide much higher efficiencies since all tidal water would have to funnel through his gates and turbines, under the force of a head of detained water.
“The velocity of the water is increased relative to the head, so while Ocean Renewable claims a .3 efficiency rate we can claim a .6 efficiency rate,” he said.
Tidewater has yet to attract investment.
John Guidroz, director of project development for Gloucester, Mass.-based Free Flow Power, is currently based on the Mississippi River where his company is exploring development of a demonstration project for a unidirectional hydrokinetic system.
The company also holds a preliminary FERC permit to purse a demonstration at the Cape Cod Canal, and has landed a $1.4 million DOE grant.
The company declined to share its data.
No one has proven such “free flow” hydrokinetics are a reliable source
of energy over time. But they might.
“There are no clear conclusions,” Guidroz said. “Everyone has claims, including us. We are methodically approaching our research, and we’re focused on launching an industry, and a growth path for hydrokinetics that we believe will one day be ubiquitous.”
Some in Congress are interested in further funding and promoting these exploratory efforts.
Sen. Lisa Murkowski (R-AK) introduced the Marine and Hydrokinetic Renewable Energy Program Act this March.
The legislation has four Democrats as co-sponsors. Among other things,
it would designate $145 million over the next two years to fund early stage projects.
Jim Kozubek is a freelance science writer at Portsmouth, N.H.
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