Nova Scotia Power customers are months away from receiving electricity generated from the Bay of Fundy’s renowned tides.
After several years of research, design, and trial and error, Cape Sharp Tidal—a joint venture between Ireland-based OpenHydro and Nova Scotia Power affiliate Emera—will deploy a fully grid-connected, four-megawatt tidal array in the Bay of Fundy. One two-megawatt turbine is scheduled to be deployed by the end of 2015 with a second turbine deployed in early 2016. This tidal turbine project is expected to be the first of its kind in the world and will provide electricity for more than 1,000 customers in Nova Scotia.
The Bay of Fundy is uniquely suited for tidal energy generation; it has the world’s highest tides with a vertical range of 16 metres. The Minas Basin and Minas Passage are also well suited for tidal energy generation. Minas Basin, which forms the eastern part of the Bay of Fundy, is connected to the bay by Minas Passage, a small channel five kilometres wide and 15 kilometres long. Billions of tonnes of water flow through the passage at each turn of the tide, reaching speeds in excess of 18 kilometres per hour. As a result, Minas Passage was selected as the site of the Fundy Ocean Research Centre for Energy (FORCE), a test centre for in-stream tidal energy generation technology to study the potential for tidal turbines within the Bay of Fundy.
FORCE was established in 2009 with federal and provincial funding as well as support from EnCana Corp. and participating developers. Researchers have calculated that around 2,000 megawatts of power could be safely extracted from Minas Passage by an array of in-stream tidal turbines. (Read the full report at bit.ly/tidal1115.)
The idea of generating energy from tides is not new. In 1984, North America’s first and only tidal generating station opened at the foot of the Annapolis River in Nova Scotia. The Annapolis Tidal Station has a capacity of 20 megawatts and makes of use of technology similar to that of a conventional hydro-electric dam. This tidal power technology is known as a barrage.
A tidal barrage is essentially a dam across the width of a tidal estuary that makes use of the potential energy in the difference in the height between high and low tides. Sluice gates in the barrage are left open as the tide rises, allowing the estuary basin water levels to rise. At high tide, the sluice gates are closed and the water is held back for several hours while the tide ebbs and the sea level drops. The gates leading to the turbine channels are then opened and the water flows through the turbines generating power. The process is repeated with each turn of the tides.
The barrage model has not been adopted on a significant scale; construction is costly and, as with any large hydro-electric dam, the prospect of its construction raises numerous environmental concerns. One of the most significant limitations of this technology is the lack of viable sites. Currently, barrage generation facilities only operate in France, Korea, and Russia.
In-stream tidal turbines
In-stream tidal turbines make use of the kinetic energy of moving water to power turbines in a manner similar to wind turbines. Unlike barrages, tidal turbine technology is removable, it can be scaled up gradually, and has lower potential construction costs and environmental impacts.
There is a wide variety of turbine designs. The Cape Sharp Tidal project will consist of two 16-metre, commercial-scale open-centre turbines with a capacity of two megawatts. Each turbine is mounted on subsea gravity base and is connected via underwater cables to an onshore substation which is connected to Nova Scotia Power’s transmission grid. The Cape Sharp project is one of four planned for the FORCE site in the coming years.
Nova Scotia’s renewable strategy
In 2012, the Province of Nova Scotia published its Marine Renewable Energy Strategy aimed at establishing Nova Scotia as “a global leader in the development of technology and systems that produce environmentally sustainable, competitively priced electricity from the ocean.” Tidal energy generation is the primary focus of the strategy, although it also contemplates development of offshore wind and wave power. Part of the strategy was the creation of a feed-in tariff for tidal generation projects with a capacity of more than 500 kilowatts.
In May 2013, the Nova Scotia Utility and Review Board approved the Developmental Tidal Energy Feed-in Tariff (FIT). The FIT rates range from $0.375 to $0.575 per kilowatt-hour for a term of 15 years. The province indicated it would limit the total impact of the Developmental Tidal Energy FIT by setting a cap on the energy to be licensed to ensure that customers’ electricity bills would not rise by more than two per cent.
On April 29, 2015, the province introduced the Marine Renewable Energy Act to implement its Marine Renewable Energy Strategy and the development of marine renewable energy resources, including waves, tidal range, in-stream tidal, ocean currents, and offshore wind, in designated areas. The act will establish a licensing and permitting regime for the development of marine renewable energy generation. In May 2015 the Nova Scotia Utility and Review Board approved the standard form of power purchase agreement for in-stream tidal array projects.
The economic benefits of developing tidal generation are expected to be felt throughout the region. Cape Sharp Tidal estimates its project will create 950 direct and indirect jobs. As well, it has awarded contracts worth several million dollars to three Nova Scotian companies for the fabrication of turbine components; development of the barge, which will deploy the turbines; and the design and manufacturing of the heavy lift winches to be used on the barge.
The installation of the four-megawatt tidal array is a key step toward the province achieving its goal of producing 300 megawatts of power, or 10 per cent of its current power supply, from in-stream tidal energy projects.
Zoë Thoms is an energy and environmental lawyer with Toronto-based Aird & Berlis LLP.