The Government says that both it and the electricity industry are working to avert risks highlighted in a sobering report on energy supply by the Electricity Commission.
Citing similar problems over the past decade, the report raises the prospect of supply problems next year.
In a document issued just before Christmas, the commission says electricity supply will be adequate in 2010 but likely to be tight in 2011.
It says investment in electricity plant is slowing, with more than 600 megawatts of new generation either cancelled or deferred until at least 2013.
Lower output is expected from the Clutha River dams because of transmission problems, and the supply of gas may be insufficient for thermal power stations to run at full capacity.
However, Energy Minister Gerry Brownlee says improved transmission should resolve many problems, as will measures taken before Christmas to boost competition.
He says that dealing with just-in-time products like electricity always produces uncertainties, but that New Zealand has done much better than many other countries, and he is confident the country is on top of its energy supply problems.