Pathways to Decarbonization

Governments, communities and business are exploring ways to shift away from fossil fuel-based energy, and looking to clean electricity systems to power the transformation. With one of the cleanest supply mixes in North America, Ontario has an advantage that will help drive broad emissions reductions in the system as other sectors of the economy decarbonize.

The Pathways to Decarbonization report explores the many elements involved in achieving these goals in responding to the Minister of Energy’s request to evaluate a moratorium on new natural gas generation in Ontario, and to develop an achievable pathway to decarbonization in the electricity system.

The scenarios presented in the report identify potential opportunities and challenges to consider, particularly as demand for electricity grows and Ontario’s resource mix evolves. While not plans for the future, they were developed using the tools, methodologies and expertise of the electricity system operator, and they provide valuable insights into the sheer scope and magnitude of the effort that will be required.

Included in this report:

  • Two scenarios describing the potential results of a 2027 moratorium on natural gas generation in Ontario’s electricity sector, and the resources and timelines needed to decarbonize Ontario’s electricity system.
  • A summary of the dependencies, risks and opportunities involved in the transition to decarbonization.
  • Actions to help ensure Ontario can both manage uncertainty and seize new opportunities as they emerge.

Pathways to Decarbonization Report (PDF)

Report Highlights

  • By 2035, the system could be less reliant on the natural gas fleet, lowering emissions by 60 per cent below the IESO’s original forecasts.
  • Attaining a decarbonized electricity sector by 2050, alongside aggressive electrification, would require a system more than double the size it is today at an estimated cost of around $400 billion.
  • Significant investments in capital, materials and labour are needed, and emerging technologies will need to be developed.

Maintaining System Reliability

Hear from the IESO’s Executive Leadership team on what is needed to maintain a reliable and affordable electricity system in the face of decarbonization.


Minister Issues Letter to IESO Regarding the Future of Natural Gas Generation – October 7, 2021

The Ministry of Energy asked the IESO to evaluate a moratorium on procurements of new natural gas generating stations in Ontario and develop a pathway to zero emissions in the electricity sector.


The Pathways to Decarbonization report was informed by the Annual Planning Outlook and the Conservation and Demand Management Framework Mid-Term Review.