MADRID - Iberian spot power prices rebounded from recent year-lows on Tuesday due to ebbing supplies of cheap wind power while demand held steady as cold weather gave way to heavy rain.

Wind power in Spain -- the world's third-biggest producer -- fell from an overnight high of 10,000 megawatts to a low of 5,400 MW on Tuesday, and was seen meandering on Wednesday and Thursday.

Spain's Met Office issued no high risk warnings for Tuesday, but estimated almost half the country was still at risk from bad weather.

Spanish power stations were meanwhile emitting an unusually high 9,617 tonnes per hour of carbon dioxide, but dealers noted that carbon prices were low after last week's Copenhagen conference and not driving power prices.

Dealers expected demand for power to drop sharply as of Thursday and stay low next week.

Demand has been rock-bottom, so (spot) prices may be particularly low next week, a trader said.

Sliding crude hauled down benchmark forwards which have been weak since September due to low prices for essential fuels like gas.

Calendar-year 2010 traded at 39.60 euros/MWh on the Omip exchange at mid-session, down 0.45 from a day earlier.

In other news, Spain's hydropower reserves dipped last week and would be enough to meet average demand for 12.7 days.

Spain's grid is still short of 2,000 MW of nuclear power because the Almaraz I plant is refueling and not due back until this week, at the earliest, and Asco I reactor is offline for maintenance until the New Year.

The remaining six nuclear plants were producing 5,341 MW, or 13.6 percent of the generating mix, according to national grid operator REE.