Adds shares in paragraph 3, analyst comment in paragraph 5, details and background throughout

July 1 (Reuters) - Britain's National Grid NG.L said on Wednesday it will invest $1.75 billion for a 35% stake in Joulent, a U.S. energy platform developing power infrastructure for data centres, as it seeks to tap into surging AI-driven demand for electricity.

The deal will help fund Joulent's first project, a 2.67-gigawatt gas-fired facility in West Texas developed in a 50/50 partnership with Chevron CVX.N, which will supply a Microsoft MSFT.O-operated data centre campus under a 20-year power purchase agreement.

National Grid shares fell 1.4% to trade at 1,230.5 pence by 1142 GMT.

AI-related electricity demand is reshaping energy markets globally. Demand from data centres that power generative artificial intelligence services rose by 17% in 2025, far outpacing the 3% growth in overall global electricity demand.

National Grid said the investment was incremental to its existing five-year capital investment programme of at least £70 billion through fiscal year 2031 and would be funded through available capacity on its balance sheet. The transaction was not expected to affect its current financial status, the company said.

"We would expect the targeted returns of this investment through National Grid Ventures to exceed the 9-10% return on equity we expect regulated networks to achieve, reflecting a slightly higher relative risk profile," J.P. Morgan analysts said in a note.

National Grid said the strategic partnership would also strengthen its existing data centre connection programme, where it expects to connect more than 10 gigawatts across the UK and the United States over the next five years.

Known as Kilby, the project has already secured critical equipment, including GE Vernova GEV.N turbines and reserved engineering and construction capacity, and is aiming to start delivering power by 2028.

Joulent is expected to be free cash flow positive from the early 2030s, National Grid said. A final investment decision on the Joulent stake is expected by the end of 2026.