Company: TSLTF
Filing Date: 2025-12-12
Form Type: SUPPL
Source: 0001193125-25-317786
Chunk: 128

Company: TRANSALTA CORP
Filing Date: 2025-12-12
Form: SUPPL
Chunk 128
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 of the generation from its 202 MW Horizon Hill wind power project. The VPPA, together with the sale of electricity generated into the SPP market at the relevant price node, achieve the fixed contract price per MWh. Under the VPPA, if the SPP pricing is lower than the fixed contract price, the customer pays the Company the difference and if the SPP pricing is higher than the fixed contract price, the Company refunds the difference to the customer. The customer is also entitled to the physical delivery of environmental attributes. The VPPA commenced on commercial operation of the facility in the second quarter of 2024. The energy components of these contracts are accounted for as derivatives, with changes in fair value presented in revenue. The key unobservable inputs used in the valuation of the contracts are the non-liquidforward prices for power and wind discounts. III. Other Risk Management Assets and Liabilities Other risk management assets and liabilities primarily include risk management assets and liabilities that are used to manage exposures on non-energymarketing transactions such as interest rates, the net investment in foreign operations and other foreign currency risks. Hedge accounting is not always applied. Other risk management assets and liabilities with a total net liability fair value of $4 million as at Dec. 31, 2024 (Dec. 31, 2023 – $19 million net asset) are classified as Level II fair value measurements. The changes in other net risk management assets and liabilities during the year ended Dec. 31, 2024, are attributable to contracts acquired through the Heartland acquisition (Note 4), offset by unfavorable market price changes on existing contracts, unfavorable foreign exchange rates on new contracts entered into during 2024, and contracts settled during 2024.

| TransAlta Corporation |     | 2024 Integrated Report |     | F52 |

Notes to the Consolidated Financial Statements IV. Other Financial Assets and Liabilities The fair value of financial assets and liabilities measured at other than fair value is as follows:

| Exchangeable securities — Dec. 31, 2024         
 Long-term debt — Dec. 31, 2024                  |     | Fair value(1) 
 Level I       | — 
 — |     | Level II |   739 
 3,447 |     | Level III | — 
 — |     | Total |   739 
 3,447 |     | Total carrying value(1) |   750 
 3,657 |
|:------------------------------------------------|: