The Irish Department of Climate, Energy, and the Environment has provisionally awarded a joint venture between ESB and Ørsted the rights to develop the Tonn Nua offshore wind site located off the coast of County Waterford, spanning 306 km2. The announcement was made on November 26, 2025.

Auction Details and Contract Terms

The Irish government designated Tonn Nua as the only site for bidders under the Offshore Renewable Electricity Support Scheme (ORESS) Tonn Nua, Ireland's second offshore wind auction. The auction offers a partially indexed 20-year contract for difference (CfD) and the right to apply for a seabed lease and grid connection for the winning bidder.

The two-way CfD has been awarded at a strike price of EUR 98.719 per MWh. The partially indexed CfD will run for 20 years from wind farm commissioning, expected in the mid-2030s. The contract for difference is designed to support the development of a 900 MW fixed-bottom offshore wind farm for the Tonn Nua site. Under the CfD terms and conditions, the Tonn Nua Offshore Wind Farm must be operational by the longstop date of 1 January 2037.

Ireland's transmission system operator (TSO) EirGrid will build the transmission assets, including offshore and onshore substations and export cables.

Project Development Timeline and Process

The Tonn Nua site is currently in an early phase of development. The project now needs to be assessed, matured, and successfully pass all gates in the joint venture's stage-gate process, including meeting the value creation criteria. The final investment decision is expected around 2031, with first power in the mid-2030s. ORESS Tonn Nua represents Ireland's second support regime for offshore renewable energy development and the first offshore wind auction under the new state-led planning regime.

The next step for the project is to seek Maritime Area Consent and a Marine Usage Licence from the Irish Maritime Area Regulatory Authority to commence surveying and assessment before submitting a planning application for the development.

Joint Venture Partnership

The joint venture is jointly owned by ESB and Ørsted on a 50/50 basis. In 2023, ESB and Ørsted entered into this partnership to jointly develop a pipeline of offshore wind projects off the Irish coast. Tonn Nua represents the first offshore wind development site to progress to auction under the partnership. Alana Kühne, Head of Region Europe Development at Ørsted, stated:

“We commend the Irish government for running a successful auction, continuing the support for the development of offshore wind in Ireland. Offshore wind will play an important part in the future Irish energy system, ensuring green, affordable, and secure energy. We will continue to work with our joint venture partner ESB to carefully assess and progress this early-stage development opportunity, including ensuring that the project lives up to our value creation criteria.”

Jim Dollard, Executive Director for Generation & Trading at ESB, commented: “ESB is delighted with the outcome of the ORESS Tonn Nua auction. It secures a clear pathway for the development of a significant project off the coast of County Waterford, marking another important step toward Ireland's renewable energy and Net Zero ambitions. We look forward to working with our partners to deliver a project that provides significant energy security and price certainty for Irish consumers.”

Company Backgrounds

Ørsted is described as a global leader in developing, constructing, and operating offshore wind farms, with a core focus on Europe. The company has more than 30 years of experience in offshore wind, with 10.2 GW of installed offshore capacity and 8.1 GW under construction. Ørsted's total installed renewable energy capacity across Europe, Asia Pacific, and North America exceeds 18 GW, spanning offshore wind, onshore wind, solar power, energy storage, bioenergy plants, and energy trading.

ESB operates as a diversified utility across the electricity market, from generation through transmission and distribution, to supply of customers, in addition to using their networks to carry fibre for telecommunications. ESB has a regulated asset base of approximately EUR 14 billion, comprising ESB Networks of EUR 11 billion and NIE Networks of EUR 3 billion.

The company holds a 25% share of generation in the all-island market and has retail businesses supplying electricity and gas to almost 1.9 million customer accounts throughout the island of Ireland and Great Britain. During the year ended 31 December 2024, ESB Group employed an average of almost 9,600 people.

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