Seasonal forecasts released March 2 by the Electric Reliability Council of Texas (ERCOT) indicate the region will have sufficient electric generation available to serve expected peak demand requirements in the upcoming spring and summer.
“In a broad range of scenarios, ERCOT expects to have enough generation available to serve peak demand this spring,” said Ken McIntyre, vice president of Grid Planning and Operations.
The Seasonal Assessment of Resource Adequacy (SARA) for the upcoming spring identifies more than 76,600 MW of generation resources available to serve expected peak demand of about 62,000 MW. This forecast is based on average weather conditions seen during the previous 12-year period and typical seasonal generation outages experienced since December 2010, when ERCOT launched its nodal market design. It assumes the highest spring demand will occur in late May, following completion of most of the routine power plant maintenance that occurs during the spring to prepare for summer demand.
A preliminary summer SARA, also released March 2, estimates summer peak demand at about 69,000 MW, based on 12-year average weather. Peak demand in 2014, a mild summer for Texas, reached 66,454 MW on Aug. 25. Currently, ERCOT estimates nearly 77,000 MW of available generation resources for this summer’s peak.
“We continue to monitor a number of factors that could affect power plant availability and demand over the summer peak this year,” McIntyre said.
Available operating reserves under the current scenarios could range from more than 5,000 MW, based on the current forecast and typical outage rates, to less than 500 MW under a scenario in which demand exceeds the forecast by about 2,300 MW at the same time outages exceed the historical average by more than 2,400 MW. The latter weather scenario reflects the extreme conditions ERCOT experienced in summer 2011.
ERCOT said it will continue to monitor the potential impacts of prolonged drought conditions, regulatory changes that could affect generation availability, and any updates to the seasonal weather forecast. Any changes will be reflected in the final summer SARA, which is scheduled for release in May.
Spring report reflects extended outage for Miller gas units
The spring SARA said that notable capacity reductions since the preliminary spring SARA report was released include the three R.W. Miller gas-fired steam units (spring capacity rating of 403 MW), which are now on extended outage due to lack of cooling water. The plant is controlled by the Brazos Electric Power Cooperative. Based on ERCOT’s drought risk analysis, no other changes to unit capacities due to drought conditions are anticipated or reflected in this spring assessment.
Additionally, capacity for the Notrees Battery Storage facility was changed from 34 MW to zero because the facility provides regulation reserves in the Ancillary Services market and is not available to deliver energy on a sustained hourly basis.
This spring SARA report shows that ERCOT does not anticipate changes to available generation capacity for the spring season due to compliance with the Cross-State Air Pollution Rule (CSAPR) or Mercury and Air Toxics Standards (MATS). CSAPR came into effect on Jan. 1, 2015, and the compliance deadline for the MATS rule for units that have not received compliance extensions is April 15, 2015. ERCOT said it continues to monitor implementation and consults with generation resource owners on their compliance plans for CSAPR, MATS and other environmental regulations.
The spring SARA shows the coal-fired JT Deely Unit 1 (430 MW) and Unit 2 (420 MW) of CPS Energy as being on mothballed status. Under seasonal mothballing, which means they can be more readily brought back to operation when demand is there, are the coal-fired Martin Lake Unit 3 (820 MW) and Monticello Units 1 and 2 (572 MW each) of Luminant.
For the summer season, expected new capacity additions in the ERCOT region include the natural gas-fired Goldsmith Peaker project with a summer rating of 294 MW, as well as 346 MW of summer peak wind capacity. This peak wind capacity was derived by applying new summer peak capacity percentages approved by the ERCOT Board of Directors in October 2014: 12% for non-coastal resources and 56% for coastal resources.