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Concord Coaldale GP2 Ltd. Coaldale Solar Project Battery Energy Storage System Addition, AUC Decision 27216-D01-2022

Link to Decision Summarized

Battery Energy Storage – Facilities


Concord Coaldale GP2 Ltd. (“Concord”) filed an application with the AUC for approval to alter the already approved Coaldale Solar Project (the “Power Plant”) by adding a 21-megawatt, 42-megawatt-hour battery energy storage system (“BESS”) within the existing fence line of the Power Plant (the “Project”).

The BESS will allow for two hours of storage and charge primarily from on-site solar production and discharge to the 25-kilovolt distribution system while also having the ability to charge from the distribution system.


The AUC approved the application from Coaldale to add the BESS to the Power Plant.

Applicable Legislation

Alberta Utilities Commission Act, SA 2007, c A-37.2 – s. 17.

Hydro and Electric Energy Act, RSA 2000, c H-16 – ss. 11, and 19.

AUC Rule 007: Applications for Power Plants, Substations, Transmission Lines, Industrial System Designations, Hydro Developments and Gas Utility Pipelines

AUC Rule 012: Noise Control

Pertinent Issues

Concord contracted RWDI Air Inc. (“RWDI”) to conduct an air quality assessment. RWDI used the United States Environmental Protection Agency’s Acute Exposure Guideline Levels (“AEGL”) to measure the threshold hazard criteria associated with the toxicity of hydrogen fluoride (“HF”), as recommended by Environment and Climate Change Canada (“ECCC”).

The AEGL system characterizes three concentration levels, or tiers, with associated exposure times, ranging from transient easily reversible impacts (“AEGL-1”) to life-threatening health effects (“AEGL-3”). RWDI selected AEGL-2 as the appropriate exposure criteria based on recommendations by ECCC. AEGL-2 is described as “the airborne concentration above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.”

RWDI determined that downwind HF concentrations at or above AEGL-2 will extend up to 144 metres from a BESS unit involved in a fire. Because the nearest resident is located 330 metres from a BESS unit, they would be expected to experience HF concentrations less than AEGL-2 in the event of a fire.

The carbon monoxide (“CO”) model submitted by Concord indicated potential exposure to AEGL-2 concentrations of CO at nearby residences. Concord believed the likelihood of a thermal runaway event to be extremely low given the significant and growing number of stationary BESS currently in operation and the relatively infrequent occurrences of thermal runaway events. Concord also explained that to qualify under the worst-case scenario for CO concentrations, potentially affected residences must meet several environmental criteria simultaneously. The AUC accepted Concord’s explanation that the likelihood of all criteria being met at the same time and a thermal runaway event occurring is extremely low. The AUC was satisfied that Concord’s risk assessment was reasonable and appropriate and that Concord had adequately identified, assessed, and mitigated potential risks to nearby residents in the event of a fire or emergency at the BESS. The AUC therefore approved the amendment to the Power Plant.

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