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Tapping into the Tides Provinces Explore Bay of Fundy's Renewable Power Potential
April, 2008
By Barbara Carss
Nova Scotia and New Brunswick are evaluating the viability of one of the world's most unique and predictable renewable energy supplies. The Bay of Fundy represents a particularly potent resource for Nova Scotia, where a 2006 feasibility study concluded that the Minas Passage and Minas Channel together have the capacity to generate nearly 300 megawatts (MW) of electricity.
This power source could be harnessed through in-stream tidal energy technology that employs submerged turbines to capture kinetic energy from inward and outward tides. In contrast, Nova Scotia's existing 20-MW tidal generating facility in Annapolis - one of only three such tidal power stations in the world - operates with now outmoded infrastructure that physically obstructs and redirects the tidal flow and the marine life within it.
"The beauty of in-stream tidal technology is that a dam is not required. It is using the kinetic energy in the moving water," explains Roger Bedard, Ocean Energy Leader with the Electric Power Research Institute (EPRI), which oversaw the 2006 feasibility study. "The best location is a constricted channel where a lot of water is flowing through during the tides, and the Minas Passage has a lot of fast-flowing water going through four times a day with the tides."
Provincially retained consultants coordinated through Nova Scotia's Offshore Energy Environmental Research Association have just delivered the findings and recommendations from a yearlong strategic environmental assessment (SEA) process to the Minister of Energy, Richard Hurlburt. If he gives the go-ahead later this spring, three proponents chosen through a parallel request for proposal (RFP) process will begin the project specific environmental assessments to allow three demonstration turbines somewhere in the Minas Channel or Passage. These projects have an envisioned total output of approximately 4 MW and could potentially be generating electricity as early as the fall of 2009.
CAUTIOUS AGENDA
Meanwhile, New Brunswick has just embarked on a strategic environmental assessment for its portion of the Bay of Fundy. The two provincial governments jointly funded a background study to inform their separate SEA processes, which recommended that further data on several unknown environmental impacts is still needed and should be collected in conjunction with future demonstration projects. For now, though, New Brunswick will limit its focus solely to research. Winning proponents should soon be announced from an RFP that called for researchers to conduct environmental studies that could be possible precursors to development.
"The RFP is not allowing anything to be tested. Rather than test devices at this time, because there is already a facility [in Europe] that does that now, we see the need for research," says Heather Quinn, a Policy Advisor with New Brunswick's Department of Energy. If the provincial government opts to proceed with in-steam tidal energy development, these research proponents would be given the first rights to do so in the areas where they've conducted the preparatory studies.
"It is kind of a gamble for industry," Quinn acknowledges. "We are asking them to invest money for research and we are not promising at this time that there will be an opportunity for development. If it's deemed to be not suitable for development then nothing will happen."
Similarly, the Nova Scotia government has confirmed that all plans will be halted if the strategic environmental assessment finds that development will pose a risk to the environment or to other major industries - notably fisheries - that the Bay of Fundy sustains. However, proponents are optimistic that both the SEA and the Minister of Energy will be supportive of the demonstration project. Indeed, the provincial government has committed $4.7 million from its Ecotrust for Clean Air and Climate Change Program to help cover capital costs, as well as $300,000 for studies and documentation required for environmental approvals and development permits.
TARGETS OPEN WAY TO TEST EMERGING TECHNOLOGY
The Nova Scotia government has also pledged to reduce province-wide greenhouse gas emissions to 10% below 1990 levels by 2020. To do so, the current reliance on coal-fired generation will have to be curbed. Regulations dictate that almost 20% of the province's electricity supply must come from renewable sources by 2013.
"That target is pretty aggressive and that's really required the Province to look at tidal energy," says Glen Darou, President and CEO of Vancouver-based Clean Current, the developer of one of the turbines chosen for the demonstration project. "There is a very large market about to explode and it's driven by the need for renewables, but it's also driven by governments setting these targets for renewable energy."
In addition to Clean Current, two Nova Scotia based companies have been chosen to participate in the proposed demonstration project. Minas Basin Pulp and Power Co. Ltd., which has a long history of operations on the Bay of Fundy, will build the facilities and install the subterranean cable for all three turbines. It will also test a UEK hydrokinetic turbine, which is tethered to the ocean floor and designed to float somewhat like a kite to the optimal place in the water column.
The Clean Current turbine and the OpenHydro Turbine, which was designed/developed by Ireland's Open Hydro Group Ltd. and will be operated by Nova Scotia Power Inc., are both round in shape with a sheath around the outer circumference of the blade tips. There is an opening in the middle that is primarily an efficiency feature of the design, but could also allow marine life to pass through.
"There is only one species of whale, the Blue Whale, that couldn't pass through a five-metre hole and it's not found in the Bay of Fundy, but, realistically, we don't think any whale will go near the device," Darou notes. "Marine biologists tell us that only fish and sea mammals that can handle fast moving currents swim in those waters. They will sense the turbine generator because of back-pressure on the water and the low frequency noise and they will swim around the turbines."
All three turbines are horizontal axis models - a design that's well suited to deep water where there will be plenty of room for the expansive radius of the turbine's blades and 15+ metres of clearance above to avoid any interference with overhead vessels. This configuration supports the greatest generating potential since power generation is proportional to the square of the turbine diameter and the cube of the water velocity flowing through it.
"If the velocity doubles, you get eight times as much power. If you double the radius or diameter of the unit, you get four times as much power," Darou says. "We need deep water as well as fast currents."
PRODUCTION CAPACITY AND COSTS
Depths in the Minas Channel and Passage are typically 40 to 50 metres. Other kinds of turbines, such as vertical axis, cross-flow or oscillating, may be better suited for shallower water.
Bedard points to San Francisco where a turbine placed to capitalize on the constricted waters flowing beneath the Golden Gate Bridge could produce a modest but viable output because of its proximity to the demand load. In most cases, tidal energy tends to be limited to this kind of distributed generation application where the power supply is located amid its consumers and is connected to the grid at lower level voltages or connected directly to the load itself. As such, it's really only feasible if there is sufficient demand nearby to take advantage of the renewable resource.
This is one of the possible obstacles to eight areas within New Brunswick's portion of the Bay of Fundy where the EPRI study identified tidal energy potential. "In New Brunswick the resource is up in the Cumberland Basin where there's not too much of a demand for the load," Bedard observes.
The Minas Channel and Passage offer a unique scenario in North America of producing enough power for central power generation that could be linked into a major transmission grid. Because it is highly predictable - unlike wind - tidal power is considered easier to sell into the marketplace, which could also make it an attractive export to the northeast United States.
Proponents see other cost efficiencies as well. Although the capital costs of building a generating facility will be steep because underwater construction is required - the cost of subterranean cabling is approximately 10 times the cost on land, for example - fewer and smaller turbines would be needed.
"The power density in water is about 50 times greater than the power density in air. It costs more to install it, for sure, but the cost is lower per unit amount of energy collected than with a wind turbine," Bedard says
ECONOMIC DEVELOPMENT OPPORTUNITIES
If environmental approvals are granted, the three turbines will be located in a cluster within the Minas Channel or Passage. Certain areas will likely be designated off-limits due to competing uses, so the three proponents will work together to identify the best generating conditions with the fewest logistical hurdles for installing equipment. "We're trying to find a location where everyone will be successful," says John Woods, Vice President, Energy, with Minas Basin Pulp and Power.
The companies will have a multiple year lease, with the possibility of further extensions, after which the turbines and associated infrastructure will have to be removed from the water. Decision makers will monitor and assess several different aspects of the projects' performance during the test period. Scientists will gather evidence of the turbines' environmental impact; financial analysts will consider the cost effectiveness of power production; engineers and researchers will look at ways to further refine the technology; and economic developers will measure and forecast spinoff effects on other businesses.
"People very much want to be sure that, if tidal energy does go ahead, this development benefits Nova Scotia and provides some benefit to the local region around the Bay," says Lesley Griffiths who has been on the frontline of public consultations as the lead coordinator of the strategic environmental assessment process. "I think it's safe to say that the majority of people are very supportive of renewable energy in general, and everyone knows the Fundy tides represent this specific potential for development. There is a lot of general interest and support, but people would not want to see development of renewable energy in the Bay adversely affect another renewable resource, namely fish harvesting and other marine resources for food."
Minas Basin Paper and Power, which is one of the longest established companies in Nova Scotia, is already an early example of the kind economic diversification that provincial strategists hope to see. The company has operated a 5-MW hydroelectric facility at its mill for about 80 years, but just launched its energy division in 2007.
In addition to the tidal energy demonstration project, it is working with Manitoba Hydro to test the UEK kinetic turbine on the Winnipeg River in Manitoba. The company recently announced plans for a 5 to 7-MW biomass-fueled cogeneration plant and is developing a 100-MW wind farm.
"Continuing to operate as a paper company may not be sustainable," Woods says. "Moving into the energy field was something that made sense."
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