He is the former DJ and punk music enthusiast who played an integral role in Australia's response to the global financial crisis, but now Reserve Bank deputy governor Guy Debelle is taking on a new challenge: attempting to turn a mining giant into a green energy powerhouse.

Ahead of the looming federal election, Dr Debelle has announced his resignation from the RBA to join billionaire mining magnate Andrew Forrest's Fortescue Future Industries (FFI) as its chief financial officer.

It is a surprise announcement given Dr Debelle was only reappointed deputy last year and was seen by many as being the front runner to be appointed the next RBA governor.

Asked why he was giving up the potential opportunity to be the next Reserve Bank governor, Dr Debelle told ABC News that this role offered the chance to make an even larger long-term contribution to society.

"It's really interesting and exciting, it's the opportunity to take a new challenge that doesn't always come along," he explained.

Dr Debelle said he had noted in recent RBA speeches that his hope was for Australia to be a clean energy exporter.

This new job would give him the capacity to do "a lot of good for the country, for the future, to try to contribute to the welfare of the Australian people".

He described Dr Forrest as a "real visionary" and said that Fortescue was already moving towards a cleaner energy future.

"I very much buy into that proposition," Dr Debelle said.

'That's the chairman's vocally stated position, it's not just rhetoric. It's stuff on the ground. They are already doing that [going green]."

Who is Guy Debelle?

Dr Debelle has worked at the RBA for 25 years. He has been the deputy governor at the Reserve Bank since 2016 and, prior to that, was the assistant governor (financial markets) for a decade, playing a key role in Australia's response to the global financial crisis of 2008.

Looking back on his time at the bank, Dr Debelle said reforms he played a big part in delivering throughout the global financial crisis and the recent COVID-19 pandemic stood out.

"That was a remarkable period," he said.

"The Australian economy has had a pretty remarkable period, and the Reserve Bank has made its contribution to that, and that's something to be proud of I think."

Dr Debelle has also held roles at the International Monetary Fund, Bank for International Settlements, Australian Treasury and as a visiting professor in economics at the Massachusetts Institute of Technology (MIT).

He is among several senior RBA officials who completed PhDs at MIT, including governor Philip Lowe and current assistant governor (financial markets) Christopher Kent.

How will Guy Debelle fit into Fortescue's green energy future?

Fortescue chair and founder Andrew Forrest said that the appointment was an important step in the delivery of the company's global green energy vision.

Fortescue's goal is to produce 15 million tonnes of green hydrogen per year by 2030 for global market distribution.

"Dr Debelle's appointment as CFO of FFI will help facilitate this goal while delivering value for shareholders and economic benefits for the communities where FFI operates," Dr Forrest said in an ASX statement.

Dr Forrest has appointed big names to help steer his various business and philanthropic interests.

Last year Malcolm Turnbull was appointed chairman of Australian Fortescue Future Industries, an offshoot of the main company.

Former intelligence official and Australian diplomat Nick Warner is a special adviser.

Dr Debelle will lead FFI's new Sydney CBD office, with the headquarters remaining in Perth.

"Bringing in someone of Dr Debelle's economic credibility goes to the heart of our vision for FFI," Dr Forrest said.

"Not only are we committed to arresting climate change, but we are also committed to creating economic growth, increasing jobs and growing our business profitability."

Dr Forrest said the strengthened leadership team would assist in "Fortescue's journey to become the best green hydrogen, energy and resources company in the world".

"We will prove that going green has a profitable future for companies the world over," he said.

Dr Debelle said noted Fortescue Metals Group recent acquisition of Williams Advanced Engineering (WAE) – an offshoot of Williams Formula 1 team – in its push to decarbonise its fleet and equipment.

The iron ore miner has been working with WAE since early 2021 to build a prototype battery for an electric haul truck and plans to develop an electric train project.

Dr Debelle said, in the Pilbara, the company was working towards zero energy transportation of iron ore.

"It's not like they're just saying it, they're actually doing it," he told ABC News.

He said climate change had a broad-ranging impact on Australia, both in terms of geography and in terms of Australian businesses and households.

"There are plenty of opportunities for Australia. Reflecting our endowment, Australia has been an energy exporter for many decades and there is no reason why this should change.

"Australia is also endowed with resources that have the potential for us to continue to be an exporter of energy – but renewable rather than emissions-intensive fossil fuels.

"I see this as an incredibly exciting opportunity for the future of our country and the world."

Treasurer to appoint replacement 'in due course'

RBA governor Philip Lowe thanked Dr Debelle for his time and work at the central bank.

"He has made major contributions to monetary policy, to financial market operations and to the management of the bank," Dr Lowe said.

"Guy has been a great colleague and I wish him all the best in his new position."

A new deputy governor will be soon appointed by Treasurer Josh Frydenberg, with Dr Debelle leaving the bank on March 16.

He will join Fortescue in June.

Mr Frydenberg thanked Dr Debelle for his "outstanding contribution to the RBA over nearly three decades".

"Since his appointment as deputy governor and deputy chair of the RBA board in 2016, Dr Debelle has provided strong economic leadership and helped steer the RBA board's response to the COVID-19 pandemic," he said.

The Morrison Government, he said, would announce a replacement deputy governor "in due course".