Abstract
During the last decade, Nova Scotia has once again been exploring the potential for electricity
generation from the tides of the Province, particularly those of the Bay of Fundy and Cape
Breton. Unlike the previous hundred years, the focus has been on new tidal stream technologies
that convert energy from tidal flows without the need for barrages or dams. The objectives are: to
reduce dependence on fossil fuels and enhance Nova Scotia's energy security for the future; to
capitalize on development of new tidal-stream technologies; and to contribute technological and
scientific knowledge to the global development of renewable marine energy.
Previous environmental studies, including those at the Annapolis Tidal Generating Station,
identified numerous environmental issues of tidal power, many of which are attributed to the
dam rather than the turbines. Three Strategic Environmental Assessments (SEAs) have been
conducted, two on the Bay of Fundy (2008 and 2014) and one on Cape Breton waters (2012).
Each of these examined several options for marine renewable energy, including tides, waves and
offshore wind installations, and identified their major environmental and socioeconomic
implications. On the basis of the first Bay of Fundy SEA, the province moved to establish the
Fundy Ocean Research Centre for Energy (FORCE), and set aside an area in Minas Passage as a
test facility for commercial scale tidal stream devices. The FORCE site is now equipped with
subsea power and data cables, and will see devices installed for testing at its berths in the next
years. Testing of smaller devices is occurring in other locations in the Outer Bay.
The SEAs identified a number of environmental and socio-economic concerns about tidal stream-based electricity generation. Principal concerns have related to:
- the size of the tidal resource;
- the effects of extracting energy from tidal waters on tidal range, current flows, ice, shoreline erosion, turbulence (etc.):
- the direct and indirect effects on fish, birds and marine mammals;
- the direct and indirect effects on bottom-dwelling organisms, marshes and mudflats;
- the direct and indirect effects on fisheries and other resource uses of tidal waters; and
- the opportunities and benefits to the economy and local communities of investments in tidal power
Numerous research projects have been conducted to address these questions, and, in doing so, considerable technical and scientific innovation and expertise has been developed. A suite of numerical models that describe the energy resource, flows of water, and mixing (etc.) on both large and small scales has been developed, allowing more precise prediction of the effects of extracting energy from the tides. In Minas Passage, Grand Passage, Petit Passage and Digby Gut, the energy of tidal flows would be sufficient to provide more than 2.5 GW of electricity, a 3 quantity greater than the total installed electricity capacity (~2.3 GW) of the Province, with only a modest effect on the tidal ranges at those sites. Technologies for monitoring the movements of fish and marine mammals have been investigated, particularly in the Minas Passage, and four species of fish and some lobster have been fitted with acoustic tags to investigate their behaviour as they move through the passage where turbines are to be tested. Video and sonar technologies have also been used to examine benthic life in the areas suitable for tidal stream generation, and field investigations have looked at the changes in sediments that might arise from changes to tidal water flows.
As a result of these studies, several concerns have been laid to rest. Ice and electromagnetic forces are considered unlikely to interfere with the turbines or to affect significantly the movements of animals through the passages. Some issues remain to be resolved. Priority issues relate to the behaviour of fish, birds and marine mammals in the vicinity of working turbines, the possible mortality and deterrent effects that an array of turbines might have on the normal migratory behaviour of these animals, and the population level consequences of these. The effects on fisheries for lobster, herring and other finfish and shellfish are being examined, and in some cases this requires selection and further development of suitable monitoring technologies that can withstand the difficult environmental conditions under which tidal energy could be generated.
This assessment of the potential for tidal power generation using modern tidal stream devices is being pursued as a collaborative enterprise involving government agencies, universities and the private sector, with funding primarily from the federal and provincial governments. Costs and risks are high, but the potential benefits are even greater. In addition to the size of the tidal resource, there are immense benefits to accrue from increased knowledge and innovations in technology. An assessment of the value of early involvement in tidal stream development suggests that over the next decades more than $1.7 billion could be added to the provincial GDP, with creation of some 22,000 full time positions and $815 million in labour income.
Throughout the last decade, there has been considerable effort devoted to involving all stakeholders. Public meetings were held in connection with all three SEAs, consultations have been held with Mi'kmaq, fishers and other stakeholders to access local knowledge, and results of directed research made quickly available. In order to provide the public with ready access to information, results of studies have been placed on websites operated by the Offshore Energy Research Association (OERA), Fundy Energy Research Network (FERN) and the Fundy Ocean Research Centre for Energy (FORCE). Handbooks providing information for communities and businesses to participate in tidal energy discussions and guides to engagement of Mi'kmaq and other communities have also been made available. The intent is to ensure that development of tidal-stream energy in Nova Scotia is being pursued with full understanding of the implications among Nova Scotians.