(Reuters) -South Africa's Tharisa Plc announced plans on Friday to spend $547 million on an underground platinum group metals mining project over the next decade, betting on the metals being integral to the global shift to cleaner energy technologies.

The company will transition its depleting open pit PGM and chrome co-producing Tharisa mine on South Africa's Bushveld complex to underground mining within the next 10 years, it said.

"The underground project is the natural progression for our operations and has been established to increase the life-of-mine development to access the multi-generational mineral resource base," CEO Phoevos Pouroulis said during a call.

He added that PGMs remained "critical metals and minerals that the world has realised are a necessity to transition to a future world".

Despite concerns that PGMs, mainly used in autocatalysts that help curb vehicle emissions, were under threat from the growth in electric vehicle usage, the metals are considered to be useful in fuel cell technologies and clean hydrogen.

Tharisa's mechanised underground operations, which are expected to start delivering ore from the first of two shafts during the second quarter of 2026, will enhance efficiencies, lower costs and raise output, Pouroulis said.

At steady state, the underground operations are expected to deliver at least 200,000 ounces of PGMs and more than 2 million metric tons of chrome concentrate, annually. Tharisa has projected between 140,000 and 160,000 ounces of PGMs and 1.65 million to 1.8 million tons of chrome concentrates in its 2025 financial year.

The company is also developing the 226,000 ounce-per-year open pit Karo platinum mine in Zimbabwe, just one of two greenfield mine development projects in the platinum industry, along with Ivanhoe's Platreef mine in South Africa.

Miners have been wary of developing new platinum mines due to the advance of EVs and South African platinum miner Northam has said the number of PGM shafts has fallen to 53 from 81 in 2008.