The massive 30-foot tides of Alaska’s Cook Inlet and the resulting ebb and flow of powerful tidal currents break up sea ice, shorten ship transit times in the inlet and provide an unforgettable spectacle for tourists. But could these tides also become a significant electrical energy generator for the state?
At least three companies see Alaska tidal energy power generation as a possibility within the next few years.
And in a report published in June, the Electric Power Research Institute (commonly known as EPRI), a California-based non-profit research organization, estimated that the tidal currents in Knik Arm could generate an average of 116 megawatts of electrical power, although environmental constraints would probably limit the output to about 17 megawatts. By comparison, the gas-fired Beluga power station that supplies electricity into the Anchorage area has a power rating of 385 megawatts, according to Chugach Electrical Association’s 2005 annual report.
Natural Currents Services LLC is proposing to build a tidal energy facility in Knik Arm, in the narrows between Cairn Point and Port MacKenzie. Natural Currents Energy Services is part of the Natural Currents Energy Group, a small, private, New York state-based firm that specializes in the design, manufacture and installation of renewable energy systems.
The Knik Arm facility would consist of a farm of turbine-powered generators, known in the parlance as tidal in-stream energy conversion (or TISEC) devices. The turbine generators would be tethered to the sea floor by cable and float inside the water column rather like submarine blimps, Natural Currents Services President Roger Bason explained to Petroleum News.
Bason said that he has been involved in test implementations of this type of tidal power technology in New York harbor, at Shelter Island at the end of Long Island, New York, and in Florida. His company is investigating several tidal energy implementations, including the proposal for Knik Arm. TISEC devices can be placed in any form of flowing water, such as a river or the outflow from a wastewater treatment plant.
“Over the past five years we’ve developed an expertise in this so-called in-stream or free-flow hydro generation, where it does not require dams or impoundments,” Bason said. “… This is a relatively new innovation that has effectively been developed over the last 10 years.”
New technology
State-of-the-art computer simulation of tidal power sites coupled with the use of thermoplastics for generator manufacture is driving rapid advances in tidal energy technology, Bason said. The computer simulations, known as computational fluid dynamics, enable the assessment of the operation of different turbine designs and turbine farm configurations at each specific tidal power site, prior to testing the site using actual equipment.
And in recent years, the technology of the tide-powered turbines has made major progress. For example, a breakthrough design called a Gorlov helical turbine involves a series of aerofoil blades twisted into helical spirals around the perimeter of a cylindrical turbine rotor.
“That’s one system that has been tested thoroughly and performs effectively,” Bason said.
And there is now a plethora of other designs for use in different tidal power settings. E3 Inc., Natural Currents Services’ sister company within the Natural Currents Energy Group, holds patents on some of these designs.
“From a technical perspective most of the industry is in a rapidly evolving pre-commercial field,” Bason said. “We have test units that have gone through various stages of testing and we anticipate accelerating development over the next year or so.”
Bason expects some of the smaller, kilowatt-scale turbines to be market ready in the first half of 2007. But the eventual aim is the production of bigger units that are capable of large-scale electricity generation.
“What we’re doing is working to develop a megawatt-scale unit within the next two years. … Those are the units we hope to install in the Knik Arm,” Bason said.
Meanwhile something of a bandwagon is under way for tidal power generation.
EPRI has published a series of reports on the topic and those reports have created a surge of interest in the burgeoning tidal power industry, Bason said. And because the Federal Energy Regulatory Commission regulates offshore electrical power generation in navigable water, a bunch of people have submitted FERC tidal energy permit applications, to reserve sites where tidal energy generation might work.
“Right now there are something like 35 or 40 tidal power applications in before FERC,” Bason said. “So there’s been an enormous boom in speculation … with a gold rush mentality to jump and acquire these sites, because the technology will shortly be available to utilize in these different locations.”
Environmental concerns
Bason sees addressing environmental concerns as a critical to his company’s Knik Arm project. He stressed that Natural Currents Services takes a flexible approach to doing things and is open to ideas for dealing with environmental issues — a major component of the project consists of environmental studies and environmental permitting.
In its New York harbor project, for example, the company has used fish migration periods as an opportunity to do turbine maintenance.
“In New York harbor we have 32 species of fish and a lot of migration down the rivers and out into the ocean, so during those fish migrations that happen during a two or three week period during the year we can pull these turbines up and let the fish go through and do our maintenance,” Bason said.
Bason said that his company has retained some of the world’s leading experts on fish and other marine wildlife, including Dr. Peter Henderson, a director of Pisces Conservation Ltd. and a senior research associate of the Department of Zoology in the University of Oxford, England.
“We will be required and we are prepared to do very detailed evaluations of the fish impacts,” Bason said.
Bason also said that FERC supports a “plug-and-play” protocol, involving the ability to quickly pull turbines out of the water at a test site if an environmental issue arises. He also stressed the importance of assessing wildlife impacts over at least several months, to establish the facts about any environmental impacts.
According to an EPRI report, the TISEC devices are likely to be environmentally friendly.
“Anecdotal information from numerous temporary testing activities in the United States, United Kingdom and abroad have not observed any harm to aquatic life. … The blades of TISEC devices turn very slowly (around 10 rpm for an 18 meter diameter rotor) and the speed at the tip of the blade is about 10-12 meters/second (22-27 mph). The devices are self limiting in that any faster speeds result in cavitation,” the report says.
Three to five year development
According to Bason it might be possible to deploy some small test units in the Knik Arm as early as next year. But the implementation of a full-scale power station would probably entail a three-to-five year project — that means that an operational system might come to fruition late in 2009. There are some very strong currents and some significant issues with respect to engineering, Bason said.
Natural Currents Services estimates that the studies leading to initial construction will cost $1 million to $2 million and the company hopes to hire local Alaska consultants in doing this work. The company would also welcome the involvement of the University of Alaska.
“We have equipment we’ve used in the New York area that we’ve partnered with the universities to provide ships and students, and we provide the instrumentation and overall direction,” Bason said.
Bason also said that his company has investment funding to cover the costs of the project.
“We have investors that are interested in moving the technology forward and who see a great future in this,” he said.
However, Bason emphasized that his company is anxious to coordinate its activities with other local and regional developments. In particular, the project site lies close to both Elmendorf Air Force Base and to the Municipality of Anchorage. Natural Currents Services would like to know what interest either of those entities has in renewable energy supplies.
“We come with open ears to listen — we’re at a very early stage with this,” Bason said.
Cook Inlet
Another company, Alaska Tidal Energy Co., has filed a FERC permit application for a tidal power project in Cook Inlet. Petroleum News has been unable to contact anyone from Alaska Tidal Power, but the FERC application describes a plan to deploy “one or more clusters of TISEC devices connected by underwater transmission cables to electrical infrastructure onshore.” The devices might be deployed anywhere in a broad area north from the east and west sides of Kalgin Island to a line just south of the Steelhead and Baker Platforms, north of the East and West Forelands.
Alaska Tidal Energy expects to refine the TISEC designs “from the company’s pending patent application.”
The FERC application envisages “(1) rotating propeller blades, approximately 20 to 50 feet in diameter; (2) an integrated generator, producing 500 kilowatts to 2 megawatts of electricity; (3) anchoring systems supporting the TISEC device at varying depths underwater; (4) a mooring umbilical line to an anchor on the sea bottom; and (5) an interconnection transmission line.” The number of units deployed will depend on site-specific issues, including other uses of the area — the total build-out could be anywhere from 50 to 500 units, according to the application.
Alaska Tidal Energy said that it has not yet determined the exact locations of onshore electrical tie-ins and that it plans to identify and discuss “partnerships and agreements with local entities” for “using and/or distributing the energy.”
The company’s plans include extensive environmental studies, and the company expects that an environmental impact statement will be required, under the terms of the National Environmental Policy Act. The company expects that the studies and permitting associated with the project will cost between $1 million and $4 million.
“All studies associated with this project will be fully funded by AKTidal and its participating partners and investors,” the company said.
Chevron Technology Ventures is also considering the use of tidal power generation in the Cook Inlet (see sidebar).
The big picture
Bason sees initiatives such as the Knik Arm tidal energy power plant as just the beginning of harnessing the vast power locked in the oceans and other sources of renewable energy. He said that in 1997 the Marine Oversight Committee of the British House of Commons evaluated the power potential of the world’s oceans and said that: “If one tenth of 1 percent of the energy in the oceans was converted into electric power it would satisfy the demands for the entire world’s energy five times over.”
And Alaska has 50,000 megawatts of potential capacity just from conventional hydropower, Bason said. Could Alaska become a significant source of electricity for North America, perhaps via a connection to the Canadian electrical grid, he speculated.
With fossil fuels certain to run out at some time, the future will see a changing mix of fuels. And renewable energy sources such as tidal and hydropower will form part of that mix, Bason thinks.
“We have a new frontier and, whether we like it or not, a changing picture in the energy mix that will be thrust upon us,” Bason said. “We have to participate and make it something that creates jobs and opportunity for people.”
