UK GAS-Prompt prices slip as high wind power output curbs demand

* Wind power output forecast to hit 6.3 GW on Friday

* Gas market oversupplied by 8.3 mcm

LONDON, July 17 (Reuters) - British spot gas prices slipped on Friday morning as higher wind output curbed demand from gas plants.

Prices for within-day delivery were trading at 43.40 pence per therm at 0835 GMT, down 40 pence since their last settlement.

Traders said demand for gas from power stations was weak due to a forecast for a rise in output from Britain's wind farms.

"A ramp-up in wind generation has seen a marked drop-off in CCGT (combined cycle gas turbine) nominations, pushing the total demand forecast lower," said Marcel Boonaert, head gas trading at Wingas UK.

Peak wind generation was forecast at 6.3 gigawatts (GW) on Friday and 5.9 GW on Saturday (Shenzhen: 002291.SZ - news) , National Grid (LSE: NG.L - news) data showed, up from below 1 GW earlier in the week.

Wind power met around 12 percent of Britain's electricity demand on Friday morning, with natural gas contributing 31 percent.

With supply at about 165.5 million cubic metres (mcm) per day on Friday and demand expected to be about 157.2 mcm, the system was 8.3 mcm oversupplied, National Grid data showed.

Gas prices further along the curve edged lower, with the Winter 2015 contract down 0.27 pence at 46.70 pence per therm.

In the Netherlands, the day-ahead gas price at the TTF hub was 0.03 euros higher at 21.08 euros per megawatt-hour (MWh).

The benchmark European Union carbon price rose 0.04 euros to 7.71 euros per tonne on ICE Futures Europe. (Reporting by Susanna Twidale; editing by Jason Neely)