* French PM says carbon tax to be ramped up after 2014 start
* Ayrault says zero impact on households from fuel in 2014
* PM also flags nuclear power levy to help energy transition
PARIS, Sept 21 (Reuters) - A carbon tax to be introduced in France next year will generate 4 billion euros ($5.4 billion) in receipts by 2016 to help fund sweeping energy-effiency goals, Prime Minister Jean-Marc Ayrault said on Saturday.
The measure, to be levied on all fossils fuels in proportion to the emissions they generate, would yield 2.5 billion euros in 2015, Ayrault said, outlining the impact of the tax announced by President Francois Hollande on Friday.
He did not give a figure for 2014, but said there would be no impact on households next year from road and heating fuel, in keeping with a pledge not to raise further the tax burden.
The Socialist government is attempting a delicate balancing act in satisfying demands for tougher environmental targets from its Green Party allies and resentment among households and businesses over rising taxes.
In addition to the carbon tax, the government will impose a levy on profits from France's large nuclear power network, Ayrault said, without detailing its value.
"Fossil and nuclear energy will thus be mobilised to allow us to meet our energy transition objectives," Ayrault told a conference in Paris.
The carbon tax would let France invest an extra 1 billion euros in its so-called energy transition from 2016, on top of nearly 4 billion euros already spent annually on renewable energies and 1 billion on household renovation, he said.
On Friday, President Hollande said France should aim for a 30 percent cut in fossil fuel use by 2030, setting out plans for the carbon tax from 2014 and a tax break on home insulation.
The incentives for households to carry out thermal renovation, supported by a reduced 5 percent rate of value-added tax for such work, would be worth 1.5 billion euros next year, Ayrault said in a speech closing the two-day conference on environment and energy policy.
The impact on households from the carbon tax as levied on road and heating fuel would be nil next year, Ayrault said.
For businesses, transport companies would still be exempted while industrial firms covered by carbon quotas would remain so, Ayrault said.
The carbon tax has already been earmarked to finance 3 billion euros for a tax credit already planned to improve the competitiveness of French companies, government officials added.
Elected last year pledging ambitious energy reforms, Hollande said on Friday the cut in fossil fuel use was needed to meet the country's goal of halving overall energy use by 2050.