Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 209

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 209
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 sales and portfolio optimization activities (excluding assets under long-term contract and ancillary revenues) divided by total merchant GWh produced. |

| (2) | Hedged power price average per MWh is calculated as the average sales price for all hedges and 
 direct customer sales during the reporting period.                                             |

| (3) | Fuel cost per MWh is calculated on production from carbon-emitting generation in the Gas and 
 Energy Transition segments.                                                                  |

| (4) | Carbon compliance cost per MWh is calculated on production from carbon-emitting generation, as 
 well as power purchased, in the Gas and Energy Transition segments.                            |

The average spot power price per MWh for the Alberta portfolio for the three months ended Dec. 31, 2024, decreased from $82 per MWh in 2023 to $52 per MWh in 2024, primarily due to:

| • |     | Higher generation from the addition of increased supply of new renewables and combined-cycle gas 
 facilities into the market compared to the prior period; and                                     |

| • |     | Lower natural gas prices. |

The realized merchant power price per MWh of production for the Alberta portfolio for the three months ended Dec. 31, 2024, although significantly higher than average spot power prices during the year, decreased by $7 per MWh compared to the same period in 2023, primarily due to:

| • |     | Lower average spot power prices as explained above; and |

| • |     | Lower hedge prices compared to the prior year. |

Fuel cost per MWh for the three months ended Dec. 31, 2024, decreased by $1 per MWh, compared to the same period in 2023, primarily due to lower natural gas prices. Carbon compliance cost per MWh of production for the Alberta portfolio for the three months ended Dec. 31, 2024, increased by $3 per MWh, compared to 2023, primarily due to the carbon compliance price increase from $65 per tonne in 2023 to $80 per tonne in 2024.

| TransAlta Corporation |     | 2024 Integrated Report |     | M41 |

Management’s Discussion and Analysis Selected Quarterly Information Our results are seasonal due to the nature of the electricity market and related fuel costs. Higher maintenance costs are often incurred in the spring and fall when electricity prices are expected to be lower, and electricity prices generally increase in the peak winter and summer months in our main