WHEN CANADIANS ponder the country’s energy resources, we tend to think about the West and the vast reserves of oil and gas. We often overlook our most abundant energy resource, hydro. Canada, because of its size and geography, is the world’s third largest generator of hydroelectricity, after only China and Brazil. By international standards, Canadians also depend far more on hydro than most of the world does.

In 2007, the Canadian Hydropower Association surveyed its members to determine the full potential of a form of low-carbon energy we tend to take for granted despite the fact that hydro accounts for more than 70 per cent of all renewable power in Canada.

For years, the conventional wisdom among energy experts was that most of the economically viable hydro sources in Canada had been harnessed. While almost two-thirds of Canadian electricity comes from hydro generating stations, the system’s total capacity has grown very modestly in recent years — a far cry from the 1950s, ’60s and ’70s, when Herculean dam projects in Quebec, Ontario, Manitoba and British Columbia flooded vast areas, displaced hundreds of aboriginal communities and funnelled power to the fastgrowing cities thousands of kilometres to the south. Today, hydroelectric facilities generate almost all the power used in British Columbia, Manitoba, Quebec, Newfoundland and Labrador, and the Yukon. Elsewhere, hydro stations co-exist with coal, natural gas and nuclear. Hydro’s overall share of Canada’s electricity mix has ebbed with the growth of wind, solar and biomass production in regions far closer to population centres.

The results of the association’s survey showed for the first time the full theoretical extent of the resource: the group’s consultants estimated that Canada has about 160,000 megawatts of untapped hydro power — more than twice the country’s current capacity, or the equivalent of 80 Niagara Falls. But as of 2014- 2015, only about 8,300 megawatts of hydro power capacity was either being built or under consideration, according to the federal government.

Of course, not everyone agrees that Canada should be gearing up for a new era of hydro ventures. Some environmental groups worry that hydro facilities will inflict irreversible ecological damage to ecosystems already stressed by the symptoms of climate change. “The premise that big hydro has to be part of the solution has a bunch of flaws,” says Jay Ritchlin, acting director of science policy for the David Suzuki Foundation in Vancouver. “The demand side has not been properly addressed.”

Still, the possibility exists that these very remote resources could not only be brought to market but also play a role in altering North America’s carbon performance. In recent years, Quebec and California have established a cap-and-trade market, and Ontario is poised to join. British Columbia and Alberta now levy carbon taxes, and Alberta, under Rachel Notley’s NDP government, is moving to phase out coal. The Paris climate accord further commits Canada and the United States to accelerated emissions reductions, and the federal government is promising a suite of new climate change policies.

If Canada and the United States begin to impose stiffer carbon pricing policies and accelerate the shift away from coalfired generation, Irving says the daunting economics of large-scale remote hydro development may begin to change. Such a shift, moreover, reflects the general trajectory of hydro development around the world. According to the Canadian Hydropower Association, global capacity has grown 27 per cent in the past decade alone, with significant investments in the developing world.

It remains to be seen if these trends will spark a renaissance in Canadian hydro power or if the economical and ecological challenges of building new facilities are too great.