BHP has signed a power purchase agreement with Enel Green Power, which will underpin stage one of the Flat Rocks wind farm in the southern WA town of Kojonup.

Enel will supply BHP with about 315GWh per year for 12 years, the equivalent of 100% of the current power requirements for Nickel West's Kalgoorlie nickel smelter and Kambalda nickel concentrator.

Construction of the A$200 million facility will begin in July, with commissioning expected in October 2023.

The new wind farm, which is being developed by Enel and local-owned Moonies Hill Energy, will comprise the 18 tallest wind turbines in WA at a tip height of 200m.

Renewable energy from Flat Rocks is expected to reduce Nickel West's market-based scope 2 greenhouse gas emissions by just under one third against FY2020 baseline levels from 2024, based on current forecast demand.

Combined with power sourced from the Merredin solar farm, the Kalgoorlie smelter, Kambalda concentrator and Kwinana refinery will be powered by 100% renewable energy.

The combined effect from BHP's agreements for Flat Rocks, Merredin and the Northern Goldfields solar project is expected to reduce Nickel West's total market-based scope 2 greenhouse gas emissions by nearly 60% against FY20 baseline levels from 2024, based on current forecast demand.

"We are taking great strides in making our operations more sustainable and strengthening BHP's position as a nickel supplier of choice to global customers," BHP Nickel West asset president Jessica Farrell said.

"We are delighted to partner with Enel Green Power as the first customer of the Flat Rocks wind farm, creating jobs and supporting the Kojonup community with the introduction of a renewable energy industry to the area."

WA mines minister Bill Johnston congratulated BHP and Enel on the announcement.

"BHP is creating a new standard for social and environmental outcomes, and setting a great example for other WA mining companies," he said.