Iberian prompt power falls on weekend, more wind

* Spain day-ahead 35.35 euros ($51.97)/MWh, down 1.11

* Portugal day-ahead falls 1.55 to 34.91 euros/MWh

MADRID, Sept 18 (Reuters) - Iberian prompt power posted a customary drop on Friday due to lower foreseeable demand over the weekend ahead, with expected steady supplies of wind power also weighing on prices.

Producers of wind power in Spain, the world's number-three generator, saw wind parks feeding up to 4,000 megawatts to the grid on Saturday, up from a lull of 1,000 MW reached on Thursday.

Sliding crude LCOc1 prices heralded cheaper running costs for gas- and oil-fired generators, and hauled down forwards in the over-the-counter market.

Baseload calendar-year 2010 was quoted at 41.25/41.75 euros/MWh, which compares with late trades at 41.95 euros/MWh on Thursday. The "cal" is a benchmark in Europe, but infrequently traded in Spain.

Data from the CSN nuclear regulator and national grid operator REE (REE.MC) showed seven of Spain's eight nuclear plants were running normally and generating 6,263 MW between them, or 19.8 percent of total demand.

The 1,000-MW Cofrentes nuclear power station is currently refuelling and not due online again until October.

Spain's power stations were meanwhile emitting 9,312 tonnes per hour of carbon dioxide. (Reporting by Martin Roberts; Editing by Keiron Henderson)