Spain benchmark power price down 8 pct at auction

* Q1 2012 baseload sold at 52.99 euros/MWh

* 4,000 MW baseload auctioned, 363 MW peakload

MADRID, Dec 21 (Reuters) - Spanish wholesale power prices used as a benchmark for retail prices in the coming quarter fell by 8.6 percent at a quarterly auction, organisers said on Wednesday.

Spain’s power market is deregulated except for small consumers, who may choose between free-market or regulated “last resort” rates based on the so-called “Cesur” auction.

Auctioneers OMIE said producers sold 4,000 megawatts of baseload power for delivery in the January-March quarter at a strike price of 52.99 euros ($69.47) per megawatt-hour, falling from 57.99 euros at the previous sale in September.

That compares with Q1 baseload contracts which traders said changed hands at 53.10 euros/MWh in the over-the-counter market on Tuesday.

Spanish first quarter 2012 baseload power BQ1SP-1Q has gradually fallen since September, in step with crude oil prices, which are linked to the cost of gas and coal burned in generators.

In addition, OMIE -- which also runs the Iberian Electricity Market’s spot exchange -- sold 363 MW of peakload power for the first quarter of 2012 at the auction held late on Tuesday at 57.95 euros/MWh, down from 63 euros three months ago.

Average power demand in Spain is about 30,000 MW.

If the spot or “pool” price fixed by OMIE for a particular hour on a particular day is more than the reference price, producers have to pay distributors the difference.

On the other hand, if the “pool” price is below the auction price, then producers pocket the difference.

The “last resort” price is based on the Cesur auction results, and access rates fixed by the government which are designed to cover utilities’ infrastructure costs.

An Industry Ministry source said access rates would rise and cancel out the fall in the auction result, so the last resort rates paid by consumers would be unchanged in the next quarter. ($1 = 0.7628 euros) (Reporting By Martin Roberts; editing by Keiron Henderson)