Iberian prompt power mixed on variable winds

* Spain day-ahead 34.30 euros ($48.45)/MWh, down 0.52

* Portugal day-ahead up 0.27 to 35.58

MADRID, Aug 12 (Reuters) - Iberian prompt power prices were mixed but little changed on Wednesday with forecasts for weak winds showing no clear trends in the coming days.

Producers predicted that market-moving wind power in Spain -- the world's third-largest producer -- would remain within a range of 1,500-3,000 MW on Thursday and Friday.

Winds can meet 43 percent of electricity demand in Spain, but on Wednesday afternoon were supplying 1,774 MW, or just 5 percent.

Curve prices followed Brent crude LCOc1 in its early fall below $72 a barrel, and the infrequently traded calendar year 2010 contract stayed down. Oil-indexed gas and coal are burned to generate about half of Spain's power.

Baseload cal-10, the benchmark forwards contract, was reported trading at 44.05 euros/MWh in the over-the-counter market, down 0.15 from late trade on Tuesday.

Data from Spain's national grid operator REE (REE.MC) and the CSN nuclear regulator showed all eight of Spain's nuclear plants were working normally and generating 7,153 MW between them, or 20.4 percent of total demand.

Spain's generators were meanwhile producing 8,505 tonnes per hour of carbon dioxide between them.

In other news, Spanish demand for gas fell by 6.3 percent in July from the same month last year, due partly to lower consumption by gas-fired geenrators. [ID:nLC552596] (Reporting by Martin Roberts, editing by Anthony Barker)