(Photo courtesy TourismScotia Culture)Nova and courtesy (Photo

Nova Scotia Power’s Annapolis Generating Station, by the , attracts over 40,000 tourists annually. ... A Tidal Power Pioneer Adds Wind To Its Renewable Resources

ova Scotia Power Inc., (NSPI) In early February, in three of the ronment manager for power production, the first North American utility communities expressing a strong inter- Nova Scotia Power. “We are looking for Nto include tidal in its est in wind energy, NSPI, along with a community to be a partner with us in power grid, will soon be adding wind community representatives, co-hosted launching this program and showcasing power to its electrical system arsenal. open houses to give local residents the this technology in the province.” Based on available-wind studies, opportunity to gain a better understand- In addition to the purchase of two Nova Scotia Power has selected West- ing of the site selection process and of commercial wind turbines, Nova Scotia ern Valley, the Amherst area, and the wind power in general. Power has also requested independent western coast of Cape Breton as poten- “Providing emission-free power producers to supply up to 50 tial sites for installation of the first of harnessed from the wind is an important megawatts of wind power to the provin- two wind 600 kilowatt turbines pur- part of our goal to improve air quality in cial grid. The company wants to enter chased by the utility. Nova Scotia,” said Terry Toner, envi- into discussions leading to long-term March / April 2002 ELECTRICAL LINE 29 contracts with wind power producers, local or world wide, willing to build wind turbines in Nova Scotia to supply Generating Station the provincial grid. cross section “A number of circumstances are com- bining to make this the right time for wind power,” said Joan McDougall, manager of green power development. “The technology has matured. Nova Scotia has an abundance of this renew- able energy source. And consumers across the country and here in Nova head pond Scotia are saying they are ready for green power.” Criteria for the first Nova Scotia com- munity to be selected for commercial wind power will be based on factors water such as a stable wind regime, strong direction turbine community support, proximity to the power grid, and potential for expansion. Site selection will be made this spring and installation of the wind turbines is scheduled for completion this year. The selection of a launch community Tidal Generating Station, a federal and in France on the estuary of La Rance, for the first two wind turbines, which provincial government pilot project ini- near St. Malo, with a generating capac- will be able to produce enough energy tially designed to explore harnessing ity of 240 MW on the incoming and for about 400 homes, opens the door energy from the sea that now con- outgoing tide, while the smallest is for other communities in the province tributes its 20 MW capacity to the located in Russia on the White Sea, to participate in future wind power provincial grid. Construction of the with a capacity of 0.5 MW. development. Annapolis project began in 1980, was The Annapolis plant is located on a completed four years later, and carried small island at the mouth of the Annapolis... One Of Three Tidal with it high expectations for its technol- near , Generating Plants In The World ogy to find application not only for tidal by the Bay of Fundy - a bay noted for Nova Scotia Power distinguished power but also for low-head rivers producing the highest tides in the itself as being home to the first and only throughout . world. Tides at the Bay of Fundy’s east- modern tidal generating plant in North Annapolis station is one of three tidal ern extremity, in the , aver- America. In 1984, the company power plants in the world. Of its two age 12 metres but can reach up to 16 assumed operation of the Annapolis counterparts, the largest one is located metres in height. Besides the Bay’s 30 ELECTRICAL LINE March / April 2002 exceptional tides, another factor that Straflo Turbine 3 favoured locating the station at cut-away schematic 4 Annapolis was an existing causeway 1 wicket gates 3 stator 1 already equipped with sluice gates for 2 turbine 4 rotor control of a head pond that would be 2 required as a key component of the power plant’s operation. Tracing the plant’s generating cycle, starting with the incoming tide, when the sea level reaches the level of the head pond, the causeway’s sluice gates are opened to fill the head pond. When the pond reaches its maximum level (less than high tide in the case of water direction Annapolis), the sluice gates close to trap the seawater upstream from the “Depending on the cycle when a storm tion of such enormous proportions turbine. As the tide recedes, a head passes through, it can lower production would have upon tides along the coast. develops between the head pond and 3 to 5 per cent,” Mr. Berringer said. As far as the Annapolis area is con- the seaside. When a head of 1.6 metres But in order to maximize production, cerned, Nova Scotia Power’s tidal gen- or more is produced, the 18 wicket why doesn’t the Annapolis station use a erating station has been more than just a gates of the distributor assembly open. double-effect turbine that could gener- good source of clean, . These wicket gates, which resemble ate power in both directions? It has also been a source of tourist inter- venetian blinds arranged in a circle, “There are a couple of reasons”, Mr. est, attracting more than 40,000 visitors control the flow of water through the Berringer, said. “While double-effect annually, as well as engineers and turbine. When they open, water rushes turbines generate more than single-effect investors from around the world who through at the rate of 400 cubic metres turbines, their output is considerably less are interested in its technology and its per second and turn the turbine’s mas- than twice as much. More importantly, potential both as a resource, and an sive four-blade runner. This power- as far as the Annapolis is concerned, investment opportunity. generating phase of the cycle contin- they also require higher head.” Nova Scotia Power is the primary ues until the level of the head pond has By way of example, he added, operating subsidiary of Inc., a dropped to within 1.6 metres of the “Double-effect turbines as large as the diversified energy company, based in incoming tide, which it does in just one we’re using at the Annapolis plant Halifax, Nova Scotia, with a customer over five hours. Then, the wicket gates would be better suited for use farther base of 550,000 customers. Ω close, awaiting a repeat of this twice- up the Bay where the average tides are daily tidal cycle. The Annapolis sys- higher. The tides at Annapolis average Circle 30 on Reader Service Card tem uses a single-effect turbine that 7 metres, which is about 4.5 metres generates electricity only in one direc- short of what’s needed for a double- tion - when the flow of water is effect turbine”. towards the sea. With clockwork regu- The potential for tidal power in the ANNAPOLIS TIDAL larity, in harmony with the high-tide Bay of Fundy is enormous and many GENERATING STATION rhythm of the sea, the Annapolis sta- ambitious projects have been consid- tion feeds the grid every 12 hours and ered for sites in both the Cumberland SPECIFICATIONS 25 minutes. Basin and Minas Basin. The one pro- Location: “During that twenty-four hour posed for the Minas Basin would span Annapolis River between Granville’s period, the Annapolis station comes on eight kilometers, be outfitted with 97 Ferry And Annapolis Royal for five hours, then it’s off for seven sluice gates, a three-kilometre long Sluices: 2 hours, generating about 30 gigawatt powerhouse with 128 double-effect hours annually,” said Don Berringer, turbines, and have an installed capac- Units: 1 Nova Scotia Power’s manager of ity of more than 5,000 megawatts. A Depth: 30.5 m (100 ft.) hydro production. “That’s enough smaller development proposed for the energy to power over 4,000 homes,” Cumberland Basin would use 42 tur- Length: 46.5 m (153 ft.) he added. bines and have an installed capacity in Capacity: 20 MW Mr. Berringer also noted that the excess of 1,400 megawatts. electricity output is not in a straight However, before any such large Energy Production: line, but varies depending upon tides scale projects could be installed, more 50 GWh (annual operation) and weather. It almost doubles when environmental studies as to their Water Flow: tides are highest but also reacts notice- impact on fish populations, head pond 408m3/sec. (14,418 cu ft/sec) ably to the barometric pressure as siltration and, in the case of the of the storms move in and out of the area. Minas Basin project, the impact a sta-