This obligation is from the 2009 investment agreement between Turquoise Hill, the government of Mongolia and Rio Tinto as well as the subsequent Power Sector Framework Agreement, which was signed in 2018.

In compliance with these agreements, Oyu Tolgoi LLC has submitted to the government of Mongolia a feasibility study for the Tavan Tolgoi Power Plant (TTPP) project, which involves building a 300MW coal power plant. In parallel with the TTPP project, and in consultation with the government of Mongolia, Rio Tinto is also progressing alternative options to source domestic power, including a renewable power component.

Arnaud Soirat, chief executive of Rio Tinto Copper & Diamonds, said: "Rio Tinto, Turquoise Hill and the government of Mongolia are all committed to securing a reliable and long-term domestic power source for the Oyu Tolgoi mine and are working together to achieve this."

The TTPP feasibility study envisages a 300MW power plant with a project cost estimate of around US$924 million. This is already included in the group capex guidance of US$7 billion in 2020 and US$6.5 billion each in 2021 and 2022.