Technology involved in the Hillside and Mozal project was developed by French producer Pechiney, which is also a major producer of aluminum, matching BHP Billiton's production.

The two groups vie for fifth spot in the aluminum producers' league.

However, about six months ago Pechiney decided that it would no longer sell its most advanced technology, presumably on the basis that its earnings from the sale of its technology did not offset the fact that it was strengthening the hand of its opposition in the smelting business.

The AP30 system, which is used in Hillside and Mozal, is still for sale, but it has decided to keep the AP50 system to itself.

The 30 and 50 figures refer to the megawattage produced by the plant, and such large increase in the capacity of the plant to chew electricity will bring down costs.

However, it seems that Pechiney recently had something of a change of heart, and it will now share the technology if its partner brings something to the table.

This could open the way for BHP Billiton, which can bring to the table a large, secure, wholly owned source of alumina at its Wolsley mine in Western Australia.

But it might have other things to offer too: tax breaks and low electricity costs.

The Coega project is desperately looking for an anchor tenant, and they are unlikely to forget that Billiton was originally supposed to fulfil this role.

BHP Billiton CEO Brian Gilbertson has hinted that a further aluminum plant is not inconceivable for the southern African region.

If the project were to take place at Coega (and it so far does not appear on the company's extensive list of greenfields and brownfields projects), the company will be able to offer Pechiney extensive local knowledge in building and running such a plant.

But even if the two companies are amenable to the idea, the developers of Coega will not have it all its own way. Their main competitor will be western Australia, which also has a lot to offer.

Not only will the smelter be close to the source of alumina; BHP Billiton might be able to generate the electricity needed using the gas it is producing in the region.

This would be an intelligent multiple use of resources the group produces, and an elegant way of demonstrating the utility of being a multiresource company.

If Coega does want the plant, it will have to put up a good fight.