TransAlta has agreed to sell most of the tax credits from two Oklahoma wind farms to Stonehenge Capital for the next ten years. The farms total 502.5 MW and both already have big tech buyers for their power. No amount has been disclosed. What has been disclosed is the share of credits sold and how long the arrangement runs, and those two facts say more about the deal than a headline number would.
Key takeaways
- TransAlta Corporation entered into 10-year transfer agreements to sell about 80 percent of the expected production tax credits from its White Rock and Horizon Hill wind projects in Oklahoma to Stonehenge Capital, announced on 4 March 2024.
- The value of the TransAlta tax credit sale to Stonehenge Capital has not been disclosed, and Leap records no amount for the financing.
- The 301 MW White Rock wind project in Caddo County, Oklahoma, sells its power to Amazon under a PPA signed in December 2021; its 99.5 MW western phase reached commercial operation in December 2023.
- The 201.5 MW Horizon Hill wind project in Logan County, Oklahoma, sells its power to Meta under a PPA signed in April 2022, with commercial operation expected in the first quarter of 2024.
- Enerdatics records six US wind tax credit transfer financings announced between January 2023 and December 2025, and TransAlta's is the only one of the six without a disclosed amount.
What exactly is TransAlta selling?
It is selling future tax relief for cash. A production tax credit, or PTC, is a US federal incentive paid for every megawatt-hour a qualifying renewable project generates over its first ten years. The Inflation Reduction Act made these credits transferable, so a developer that cannot use them against its own tax bill can sell them to a company that can.
Stonehenge Capital is the buyer. TransAlta keeps about a fifth of the expected credits and sells the rest across a full decade. Because PTCs depend on generation, the credits only exist once the turbines spin. That makes the sale a forward contract on the wind farms' output, not a one-off payment for a fixed asset.
The proceeds go to construction and development of both projects. Marathon Capital acted as TransAlta's exclusive financial adviser.
Why sell 80 percent rather than all of the credits?
Because production credits are uncertain until the wind blows. A ten-year sale has to price in the chance that the farms generate less than forecast. Selling about 80 percent of the expected credits leaves a buffer: if output falls short, TransAlta can still deliver what it promised, and if output runs ahead, it keeps the upside.
The length matters too. A ten-year agreement covers the whole credit period for each project. That gives TransAlta a contracted stream of tax credit income that matches the long-term power contracts with Amazon and Meta, which is the kind of revenue lenders and investors prefer.
This approach is becoming familiar. Matrix Renewables presold a decade of production tax credits from its Pleasant Valley solar farm in Idaho in February 2024, also without attaching a number. Investment tax credits work differently: they are earned once, when a project starts operating, so they can be sold as a single block with a single figure, as in Tokyo Gas's $118.5 million credit sale from its Longbow battery.
Why do the Amazon and Meta contracts matter to the credit buyer?
Because they make the generation more certain to be sold. A credit buyer is exposed to whether the turbines run and whether the power has somewhere to go. Long-term contracts with two large corporate buyers should reduce the risk that a project is curtailed or idled for commercial reasons.
Both farms sit in the Southwest Power Pool, the grid operator covering Oklahoma and neighbouring states. Both began construction in December 2022. White Rock is being built in two phases: a 201.5 MW eastern phase and a 99.5 MW western phase that reached commercial operation in December 2023. Horizon Hill is a single 201.5 MW project. Taken together, the two farms add 502.5 MW of wind to TransAlta's US fleet, and the credit sale arrives just as they move into operation.
Enerdatics' data shows how thin and how variable the record of US wind tax credit transfers still is. Leap records six such financings announced between January 2023 and December 2025. Five carry an amount: $580 million from a portfolio sale to Bank of America by the Invenergy, Blackstone and La Caisse platform in August 2023; $100 million from eight Avangrid wind farms to Vitol in September 2023; $221 million of investment tax credits from an undisclosed wind farm in December 2025; and two smaller sales of manufacturing credits by Broadwind, of $16 million and $35 million. TransAlta's is the only one of the six with no amount on record.
What does the deal signal for US wind financing?
It signals that transferability has become a routine tool for project owners, not a novelty. The first transfer deals Leap records for wind in 2023 were portfolio sales announced with headline figures. By early 2024, developers like TransAlta were using ten-year agreements quietly, as one piece of a financing plan alongside corporate PPAs.
It also signals a disclosure problem for anyone benchmarking credit prices. The decade-long production credit sales in this sample, TransAlta's and Matrix's, are exactly the ones that came without a number. That leaves the market leaning on one-off credit sales for price signals. Arrangements such as Schneider Electric's purchase of ENGIE's Texas tax credits show how varied the structures already are.
For TransAlta, the trade is clear even without the price. It has turned most of a decade of uncertain tax benefits into contracted cash, while its two newest wind farms start delivering power to Amazon and Meta.
Frequently asked questions
What did TransAlta sell to Stonehenge Capital? TransAlta agreed 10-year transfer agreements to sell about 80 percent of the expected production tax credits from its White Rock and Horizon Hill wind projects in Oklahoma to Stonehenge Capital. The value was not disclosed.
How large are the White Rock and Horizon Hill wind projects? White Rock totals 301 MW across two phases of 201.5 MW and 99.5 MW, and Horizon Hill is 201.5 MW, for a combined 502.5 MW in Oklahoma.
Who buys the power from TransAlta's Oklahoma wind farms? Amazon buys White Rock's output under a PPA signed in December 2021, and Meta buys Horizon Hill's output under a PPA signed in April 2022.
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