UPDATE 2-U.S. power and natgas prices spike in Texas and California heatwaves

 (Adds details on generation outages)
    June 15 (Reuters) - Power and natural gas prices in Texas and California spiked this week to their highest levels in
months as homes and businesses cranked up air conditioners to escape brutal heatwaves.
    The Electric Reliability Council of Texas (ERCOT), which operates most of the state's power system, urged consumers on
Monday to conserve energy during peak hours through Friday. The California ISO, which operates most of that
state's grid, told consumers to prepare to conserve energy if needed.
    Both grids have imposed rotating outages over the last year to avoid widespread collapses of their power systems -
California in August 2020 and Texas in February 2021.
    Rotating outages are supposed to leave a limited number of customers without service for a short time before switching to
another group of customers. In Texas, ERCOT drew criticism after millions of homes and businesses were left in the dark -
many for days.
    For this week, ERCOT forecast power demand would peak at 70,816 megawatts (MW) on Tuesday, up from 69,943 MW on Monday,
which was a record high for June. The grid's all-time high was 74,820 MW in August 2019. One MW typically powers about 200
homes on a hot summer day.
    To meet that peak and have enough reserves in case something goes wrong, ERCOT has said it expects to have about 86,862
MW of supply available this summer. On Monday, however, the grid said an unusually large 11,000 MW of generation was out of
    About 1,200 MW of power was regained overnight as some repairs were completed, it said on Tuesday.
    In California, the ISO forecast power demand would reach 39,856 MW on Tuesday and 41,219 MW on Wednesday. That compares
with the grid's all-time peak of 50,270 MW in July 2006.
    To meet that peak and have enough reserves, the California ISO said it expects to have about 50,734 MW of supply
available this summer.
 Power and Gas Prices State        Price for Monday  Price for Tuesday   Price for Wednesday     2020 Average
 Power                                                 MWh                MWh                  MWh                 MWh
 Ercot North EL-PK-ERTN-SNL       Texas              $84               $407                                    $25.52 
 Palo Verde EL-PK-PLVD-SNL        Arizona           $158               $120                  $364              $40.71 
 SP-15 EL-PK-SP15-SNL             California        $155               $120                  $190              $40.18 Gas                                                  mmBtu              mmBtu                                    mmBtu 
 Waha NG-WAH-WTX-SNL              Texas             $3.15              $3.02                                    $1.18 
 SoCal City Gate NG-SCL-CGT-SNL   California        $4.45              $8.32                                    $3.02 
 PG&E NG-CG-PGE-SNL               California        $4.09              $4.51                                    $3.01 Note - Power in Megawatt Hours (MWh) and gas in million British thermal units (mmBtu)                       
 Note - The power and gas prices this week were the highest since the February freeze in Texas boosted       
 prices across the country.                                                                                  
 (Reporting by Scott DiSavino, additional reporting by Sumita Layek; editing by Barbara Lewis, David Gregorio and Richard