For the fourth day in a row Texas’ power grid operators declared a Level 1 emergency as high energy demand collided with some 4,800 megawatts of unplanned power plant outages.
Friday’s power demand and the number of plants offline were down slightly from Thursday, however, when the state came close to initiating rolling blackouts for only the fourth time in 21 years.
The Level 1 declaration, the first stage of the state’s four-stage energy emergency system, was made at 3:10 p.m. when reserves drop below 2,300 MW.
At Level 1, the Electric Reliability Council of Texas asks all available power plants to come online, begins drawing on power from neighboring grids, including Mexico, and asks consumers to cut back usage through 7 p.m.
By 5:30 p.m. it appeared the worst was over, however, as spot prices on ERCOT’s wholesale market fell from the market-ceiling price of $3,001 per megawatt-hour to around $835. During off peak hours the prices tend to be in the $24 range.
The Level 1 was officially cancelled at 6:10 p.m.
Many power plants are expected to go offline over the weekend to repair equipment that may have limited their output during the week.
Kent Saathoff, vice president of system planning and operations for ERCOT said the grid will likely face similar challenges next week.
In addition to heat-related equipment problems, at least one North Texas power plant is having problems because the reservoir it draws water from is not cooling sufficiently overnight. ERCOT wouldn’t identify which plant had that problem.
“I have never seen anything like it in my career, and it’s strictly due to the weather,” Saathoff said of the system-wide problems.
Some 4,800 megawatts of power plant capacity were offline for unplanned maintenance Friday, according to Saathoff. This including a 650 megawatt unit at Luminat’s Big Brown coal fired plant in Freestone County (which came back on by the afternoon) and another 615 megawatt coal fired unit.
On Thursday some 5,000 megawatts of power plant capacity were offline, more than 7 percent of the state’s total capacity, pushing the state to the verge of rolling blackouts. More mechanical breakdowns occur during prolonged periods of hot weather, according to power plant operators, as units tend to run for longer hours.
Peak demand was expected to reach 67,794 megawatts (as of a 1:25 p.m. projection) for Friday.
Thursday’s peak was just 66,815 MW between 4 p.m. and 5 p.m., but subtracting the approximatley 1,500 MW of load that was dropped through two power management programs, the peak would have been more like a record-breaking (if not “grid-breaking”) 68,315 MW.
The Electric Reliability Council of Texas — which oversees the high voltage distribution system for about 85 percent of the state — pulled in 1,033 MW of generation from neighboring grids on Thursday, including 230 MW from the Comisión Federal de Electricidad in Mexico. Wind power accounted for about 1,400 MW of supply during the peak hours.
Just as it did every day this week, ERCOT issued an alert shortly after midnight Friday saying the afternoon would likely see a tight margin between demand and available reserves.
The Texas Commission on Environmental Quality will waive pollution limits for power plants that are needed to come online during power emergencies, according to a notice from ERCOT:
“If/when increased demand is requested, the agency will exercise enforcement discretion for exceedances of emission limits as well as operational limits for power generating plants to ensure regulatory burdens do not contribute to the loss of critical power during this extraordinarily hot weather,” according to the statement.
In the past ERCOT has waived collateral requirements for retail electric providers — the amount of money or credit retailers must hold in reserve to guarentee they can pay their bills — most recently during the Feb. 2 cold-weather event that saw wholesale power prices spike.