TICKY FULLERTON, PRESENTER: Global miner Rio Tinto plans to streamline its aluminium business in an effort to increase profitability. The company says it wants to concentrate on long-life, large-scale, top-tier assets and therefore will sell 13 smelters and refineries in Australia and overseas.

The announcement comes a week after the carbon tax passed the Lower House, but Rio says this was only one of the reasons for the sell-off.

Emily Stewart reports.

EMILY STEWART, REPORTER: The world's second largest miner is selling off a quarter of its aluminium assets.

PETER CHILTON, RESOURCES ANALYST, CONSTELLATION CAPITAL MGMT: The aluminium business of Rio is the poorest performing asset of the group. So, some formal restructuring I think was necessary.

EMILY STEWART: Rio expanded its aluminium business four years ago when it acquired Alcan for $39 billion, but now it plans to divest 13 assets across Europe, the US and Australia.

JACYNTHE COTE, CEO, RIO TINTO ALCAN: The move will allow Rio Tinto Alcan to concentrate on its strategy to develop and operate top-tier assets and further improve the product group's financial performance.

EMILY STEWART: The revamp includes the creation of a new business unit, Pacific Aluminium, which will hold the six Australian and New Zealand assets prior to their spin-off from Rio. These include the Gove bauxite mine and alumina refinery, Boyne smelters and the associated Gladstone power station, the Tomago smelter near Newcastle, Tasmania's Bell Bay smelter, as well as its New Zealand aluminium smelters.

The principal remaining assets will be its low-cost hydroelectric smelters in Canada.

PETER CHILTON: They have been retained and there'll be further investment in some of those assets. So, that's the jewel in the crown. The other jewel in the crown is the bauxite assets at Weipa and the alumina assets in Gladstone.

EMILY STEWART: Corporate advisor Nigel Lake says it looks as though Rio is moving away from relying on coal to more green energy for power.

NIGEL LAKE, CEO, POTTINGER: As a group as a whole something like 63 per cent of their power comes from hydro. Of the resources that they're proposing to sell here, none of the power pretty much comes from hydro. So I think that power usage thing is one thing which sits behind this.

EMILY STEWART: And despite the announcement coming just a week after the carbon tax passed the Lower House, Rio Tinto says higher electricity costs was only a small part of the decision to sell.

JACYNTHE COTE: This is way beyond one country and this was way beyond one element of environmental factor. It was one of the elements, but it goes beyond Australia and the carbon regulation. This is following an in-depth strategic review.

EMILY STEWART: Nigel Lake says if anything the carbon tax has given investors certainty and made it easier to invest in Australia.

NIGEL LAKE: The carbon price itself will have a really pretty marginal impact on the cost of power. It is that that power is exposed to ongoing price rises through the price of coal over time.

EMILY STEWART: Deutsche Bank has valued the assets at around $8 billion, but analysts say there are no obvious buyers.

PETER CHILTON: So, it could well be a perspective IPO or maybe there might be some eastern European interests that might be potentially buyers, but difficult to see. Private equity - those sort of the things.

NIGEL LAKE: My assumption is that's best suited to a kind of Asian region buyer who is perhaps less concerned about the, the - I guess the power efficiency in the near term, but really has need for certainty of supply.

EMILY STEWART: For now, Rio plans to run the businesses as usual and says there'll be no change to employment.