The Tiwai Pt power price stoush will probably have a small negative effect on the price of Mighty River - but it's not a showstopper say sharemarket analysts.

The Government has opened discussions with Tiwai Point aluminium smelter's ultimate owners Rio Tinto in a bid to broker a deal after talks between the smelter and Meridian Energy reportedly broke down.

Tiwai Pt aluminium smelter's owners have contradicted a report from Meridian, saying they think a power deal can be agreed on.

Potential investors in Mighty River Power, Genesis Energy and Meridian will be exposed to the financial impacts caused by any new charges linked to water or geothermal use and land resumption.

The state-owned electricity generator and retailer yesterday reported an underlying net profit after tax of $88 million for the latest half-year after non-cash items

Meridian Energy says it's ready for partial privatisation and expects a significant uplift in operating earnings after transmission outages knocked its performance.

Meridian Energy is considering the sale of its 50 per cent stake in the A$1 billion Macarthur wind farm in Australia.

Meridian Energy is not a private enterprise but in negotiation with Rio Tinto it must act like one. If it can get a better power price elsewhere, Tiwai smelter must go.

Rio Tinto's attempt to renegotiate New Zealand's largest electricity contract, for its aluminium smelter at Bluff, comes as the company's chief executive warns of "difficult decisions" ahead.