Updates to Guideline A-5 regarding the control of air emissions from stationary combustion turbines

ERO number
Notice type
Environmental Protection Act, R.S.O. 1990
Posted by
Ministry of the Environment, Conservation and Parks
Notice stage
Proposal posted
Comment period
October 13, 2020 - November 27, 2020 (45 days) Open
Last updated

This consultation closes at 11:59 p.m. on:
November 27, 2020

Proposal summary

We want to update Guideline A-5 to align with recent federal guidance regarding the control of air emissions from stationary combustion turbines. This will enhance environmental protection by aligning with proposed new requirements for stationary combustion turbines that are eligible for the Air Emissions Environmental Activity and Sector Registry.

Proposal details

As outlined in the Made-in-Ontario Environment Plan, the ministry is committed to protecting our air, ensuring we have strong environmental standards that are protective of human health and the environment, and taking action to enforce local air quality standards.

The ministry regulates the discharge of contaminants into the air through the Environmental Protection Act (EPA) and its regulations. Guideline A-5 provides the ministry’s expectations regarding new, modified and existing stationary combustion turbines. The ministry uses the technical information in Guideline A-5 to approve stationary combustion turbines and draft terms and conditions in Environmental Compliance Approvals.

The EPA prohibits a person from operating equipment that may discharge contaminants into the air without first obtaining an Environmental Compliance Approval (ECA), and from engaging in a related prescribed activity unless the person has registered the activities in the Environmental Activity and Sector Registry (EASR). The prohibitions apply except where there are specific regulatory exemptions.

Guideline A-5 describes the technical requirements that the ministry is proposing to use as a basis to control and monitor discharge of contaminants to the air (such as nitrogen oxides and carbon monoxide), including:

  • in-stack emission limits
  • fuel specifications
  • source testing
  • continuous monitoring

By updating Guideline A-5, Ontario would be aligned with:

  • Canada’s guidelines for the reduction of nitrogen oxide emissions from natural gas-fuelled stationary combustion turbines, published in 2017
  • modern technology designs and industry best practices

Proposed updates to Guideline A-5

The key updates that we’re proposing to Guideline A-5 will help ensure that Ontario has consistent air emission limits with other provinces and territories across Canada that will also be adopting the 2017 federal guidelines.

Updates would apply to new and, under certain circumstances, modified stationary combustion turbines. These changes would include:

  • changing the applicability categories of new combustion turbines by power rating and type to determine the new in-stack emission limit for nitrogen oxides
  • changing the energy quantification to a “higher heating value” basis from a “lower heating value” basis
  • lowering the in-stack emission limit of carbon monoxide from 60 parts per million by volume (ppmv) to 50 ppmv
  • Including sulphur limits in fuels and removing sulphur dioxide in-stack emission limits
  • removing provisions for the gasification of solid fuels as they are intended to be addressed in separate guidance
  • streamlining the requirements for natural gas combustion turbines with power ratings of up to 25 megawatts, including:
    • subdividing the concentration-based limits for nitrogen oxides into two categories by thermal efficiency (i.e., less than 60 per cent versus 60 per cent or greater)
    • enabling the use of a portable gas analyzer for measuring the air emissions according to ASTM D6522-20
    • allowing thermal efficiency to be monitored using modern sensor devices to reduce the need for on-site testing

The new technical information proposed in the updated Guideline A-5 is also being considered to define operational requirements for natural gas combustion turbines that meet specified criteria in the proposed amendments to Ontario Regulation 1/17 (Registrations Under Part II.2 of the Act – Activities Requiring Assessment of Air Emissions). The regulation proposal aims to reduce burden for those operating combustion turbines that meet specified criteria by requiring registration in the EASR as opposed to obtaining an ECA and make it easier for eligible facilities to use more efficient technologies.

Supporting materials

View materials in person

Important notice: Due to the ongoing COVID-19 pandemic, viewing supporting materials in person is not available at this time.

Please reach out to the Contact listed in this notice to see if alternate arrangements can be made.


Let us know what you think of our proposal.

Have questions? Get in touch with the contact person below. Please include the ERO number for this notice in your email or letter to the contact.

Read our commenting and privacy policies.

Submit online

Submit by mail


Connect with us


Sign up for notifications

We will send you email notifications with any updates related to this consultation. You can change your notification preferences anytime by visiting settings in your profile page.

Follow this notice