Canadian hydropower is a climate disaster, not a climate solution.

As of June 2021, there are more than 36 significant scientific studies that have analyzed the GHG emissions caused by the construction and operation of dams and reservoirs. (This does not include the GHG emissions from deforestation — a forthcoming separate bibliography will focus on the global deforestation caused by dams and reservoirs.)

Canadian hydropower is not clean, green, or renewable energy. Canadian hydropower dams and reservoirs are major drivers of climate change. Over the past 60 years, Canadian hydropower facilities in use today have destroyed river ecology, biodiversity, water quality, and altered natural river flows. More dams are being built and even more are planned.  Canadian hydropower is not “run of the river” or generated by free-flowing rivers but from massive artificial impoundments. The dams trap sediment that would otherwise flow to the sea, undermining the ocean’s ability to store carbon.  

Canadian hydropower must be excluded from all subsidy programs intended for energy sources promoted as solutions to the climate crisis. It also should not be available as an option to offset greenhouse gas emissions under carbon trading programs such as New York City’s Local Law 97 building efficiency program. 

Canadian hydropower cannot deliver on jobs or climate benefits

General sources of greenhouse gas emissions from hydropower

  • Flooding lands to create reservoirs, which destroys carbon-sequestering forests, rivers, peatlands, and wetlands.
  • Manufacturing steel and concrete to build dams, transmission corridors, and associated infrastructure, construction of hydroelectric facilities, and emissions associated with day-to-day operations.
  • Trapping sediment behind dams prevents it from flowing downstream to the ocean, impairing the ocean’s ability to regulate carbon. 

In order to determine the climate impacts of hydroelectricity, the lifecycle emissions must be calculated including activities such as land clearing, construction, operation, and decommissioning.

Peer-reviewed studies have proven that dams release large amounts of greenhouse gases, often more than they store.

Hydropower greenhouse gas emissions can be on par with fossil fuels.

The study Climate Impacts of Hydropower: Enormous Differences among Facilities and over Time analyzed 1,500 hydropower reservoirs previously studied. The report concludes that “analyses of climate impacts of hydropower plants have been simplistic, emphasizing the aggregated 100-year impacts from a one-year pulse of emissions.

Such analyses mask the near-term impacts of methane emissions central to many current policy regimes have tended to omit carbon dioxide emissions associated with initial plant development, and
have not considered the impact of the accumulation of gases in the atmosphere over time. By analyzing climate impacts of sustained hydropower emissions over time, we find that there are enormous differences in climate impacts among facilities and over time. If minimizing climate impacts are not a priority in the design and construction of new hydropower facilities, it could lead to limited or even no climate benefits.

Methane emissions from dams and reservoirs are about 25% higher than previously estimated. Methane is a greenhouse gas and it’s greenhouse gas impacts are about thirty times that of carbon dioxide (CO2). Methane can account to up to 79% of CO2 emissions from hydropower reservoirs.

Resources on greenhouse gas emissions from hydroelectricity generation:

A diverse coalition of leaders including NAMRA have petitioned the U.S. Environmental Protection Agency to report greenhouse gases from dams and reservoirs

Greenhouse Gas Emissions from Hydro-Quebec Presentation by Bradford H. Hager, Cecil and Ida Green Professor of Earth Sciences Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology

Click here to access a declaration by Massachusetts Institute of Technology Professor Dr. Brad Hager on the greenhouse gas impacts of Canadian hydropower projects.

Click here for a detailed documentation of the carbon footprint of Hydro-Quebec’s hydropower.

Dam Accounting: Taking Stock of Methane Emissions From Reservoirs

The Myth of Clean Hydro: Dams and Reservoirs Emit Greenhouse Gases and Make Climate Change Worse

Save the World’s Rivers et al. Submit Comments and Publications to IPCC about Greenhouse Gas Emissions from Dams/Reservoirs

Scientific Bibliography: Dams and Reservoirs Emit Greenhouse Gases

Specific greenhouse gas emission of Canadian hydropower 

Three main factors control the volume of greenhouse gas emissions from Canadian hydropower reservoirs:

  • Area of forest flooded per kilowatt-hour (kWh) generated (deforestation caused by the hydropower project).

There are fewer emissions from damming narrow, steep valleys above treeline while damming broad forested lowlands emits more.

  • Age: new reservoirs emit about 5 times the amount of CO2 as old reservoirs (due to initial rapid decay and disturbance).
  • Temperature (forest density, methane production): low temperature is related to lower emissions and high temperatures to higher emissions.

The climate impacts of Canadian hydropower facilities, measured by grams of carbon dioxide equivalents per kilowatt-hour generated (gCO2e/kWh), varies by a factor of 10,000.  Therefore, any analysis of whether a project involving Canadian hydropower will deliver “clean” energy must be based on an analysis of where, when, and how the electricity is generated.  This has never been done for any power purchase agreement that claims to deliver “clean” energy. For more information on this, click here.

Canadian hydropower producers such as Hydro-Quebec make clean energy promises in power purchase agreements that they cannot substantiate on a site-specific basis.

Hydro-Quebec’s electricity is dirtier than natural gas

Hydro-Quebec reservoirs emit 0.5 to 2.5 times the average carbon dioxide emissions of a combined-cycle natural gas facility.

“Electrons cannot be tagged” [See footnote 16]

In order to evaluate the greenhouse gas emissions of the power supplied under a power purchase agreement, Hydro-Quebec would have to tag each electron and trace it back to the specific generating station among its 63 sites. Then it would have to evaluate the impacts of the flooding, erosion, sediment impoundment, and other factors that cause greenhouse gas emissions for each site.  Hydro-Quebec feeds all of the electricity from its stations into its distribution system without evaluating specific reservoirs and their emissions.  Electrons cannot be tagged.  A power grid is very much like a bathtub: the molecules of water drawn from the tub cannot be directly tracked from origin to end-use.  If water is withdrawn from the tub, additional water molecules can be used to refill the tub regardless of their origin. So it is with electricity – which travels at the speed of light.

Below are examples of the greenhouse gas accounting for Canadian hydropower that has never been done:

Example: Construction of transmission corridors. Not one of the corridors proposed to bring Canadian hydropower from remote areas of Canada to Boston and New York have been assessed for greenhouse gas impacts. A lifecycle emissions calculation should include the construction of the corridor.  In New York, the 330-mile corridor proposed by Blackstone Group will be subsurface: requiring drilling under lakes and rivers, roadbeds (digging up asphalt, laying down a massive cable, and reburying) which will require fossil fuel-driven equipment to be operated for years. In addition, the project requires “cooling stations” along the route to prevent fire hazards. None of this has been calculated to determine the lifecycle emissions of the New York project. 

Source: International Rivers. Three of the listed dams are in Canada: 1, 9, and 10.

Greenhouse Gas Emissions and Hydropower, Phil Raphals, Executive Director, Helios Center, 13th annual Waterkeeper Alliance Conference

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