BILLIONS of dollars in planned investment that has been frozen by carbon policy uncertainty is set to remain under a cloud, despite the government's latest moves to curb emissions.

While business groups cautiously welcomed Julia Gillard's carbon policies yesterday, big investors in the energy sector said the changes would do little to shift funding towards cleaner fuels.

Under Labor's proposal, all new coal-fired power stations would face new emissions standards and have to be ''carbon-capture and storage ready''. The government claims this will send investors a powerful signal to invest in cleaner energy, including gas and renewable power.

But energy sector sources said the new policy did nothing to address the key question hanging over their investment decisions - what, if any, carbon price to factor in.

Power companies have already slashed $10 billion off their spending plans over the next five years because of policy uncertainty, a report from the Energy Supply Association of Australia said this week.