The California Independent System Operator (ISO) said May 7 that it has determined that electricity supplies will be sufficient to meet the 2015 summer peak even under the extreme scenario of hot temperatures that only occur once every decade or so.
A boost to grid reliability will come from additional generation, mostly solar, that has interconnected to the system, stable imports and only moderate peak demand growth. The ISO’s analysis – “2015 Summer Loads and Resources Assessment” – was released on May 7.
“It is always a challenge to operate the grid under the high loads produced by sweltering summer temperatures, but our analysis shows we have the resources available to meet California’s need this year,” said ISO CEO and President Steve Berberich. “We will keep a close watch on the system, particularly in Southern California where fires, high demand and transmission congestion can cause concerns.”
Although the multi-year drought is reducing hydroelectric availability to the lowest level in 10 years, it will not materially impact grid reliability. Also, energy imports to the ISO are expected to be normal.
The 2015 summer assessment, developed in close coordination with state energy agencies, shows:
- adequate operating reserve margins under a normal weather operating scenario and even in an extreme scenario under weather conditions that occur about once every 10 years where operating reserve margins are estimated to be about 11 percent, which is healthy;
- normal and extreme hydro projections of: 1,511 MW less hydroelectricity under anticipated water runoff and stream flows; and 2,733 MW less hydroelectricity under even more restricted water runoff and stream flows;
- total generation capacity available from all resources is expected to be 54,322 MW;
- 2015 summer peak is projected to be a slightly over 47,000 MW (2014 summer peak was 44,703 megawatts set on Sept. 15 and all-time summer peak was set on July 24, 2006, at 50,270 MW.
Since summer of 2014, 2,328 megawatts of new generation has been added to the grid with solar resources accounting for 96% of the interconnections. Currently, about 6,700 MW of solar resources are connected to the grid with about 6,100 MW of wind. In total, 16,300 MW of renewable resources are interconnected, representing about 25% of the total resource mix.
In addition, the ISO has identified about 1,840 MW of demand response and interruptible load programs will be available this summer as well.
In considering the drought impact on thermal generation for summer 2015, the ISO said in the report that it is tracking the thermal power plants potential to be out-of-service due to water supply curtailments. Among the thermal units greater than 20 MW, four natural gas-fired plants that were identified to have water supply concerns during 2014 have addressed the issues by establishing alternatives or by monitoring and managing groundwater supply.
California ISO working through issues with once-through cooling regulation
The roughly 10,517 MW of natural gas fired capacity subject to the once-through-cooling regulation, which requires coastal power plants that use ocean water for cooling to be retired, retrofitted or repowered, is a continuing issue. The bulk of the generation retirements forecast to occur as a result of this requirement are not anticipated until the 2018-2020 time frame. However, the ISO is working closely with state agencies and plant owners as they develop and implement plans to for complying with these regulations in a manner that ensures electric grid reliability is maintained throughout the transition.
Of the OTC units’ 17,792 MW of generating capability affected by the regulations, 5,370 MW are in compliance. The remaining 10,182 MW of generation will be required to repower or retire in by the end of 2020, many by the end of 2017. Compliance for the Diablo Canyon nuclear plant is subject to a pending study by a Water Board Review Committee for Nuclear Fueled Power Plants.
The generating units facing OTC compliance deadlines before 2020 are:
- El Segundo Unit 4, NRG Energy, deadline of 12/31/2015, 335 MW;
- Encina Units 1-5, NRG Energy, deadline of 12/31/2017, 946 MW;
- Pittsburg Units 5-6, NRG Energy, deadline of 12/31/2017, 629 MW;
- Moss Landing Units 1-2, Dynegy, deadline of 12/31/2017, 1,020 MW; and
- Moss Landing Units 6-7, Dynegy, deadline of 12/31/2017, 1,500 MW.
The California ISO provides open and non-discriminatory access to one of the largest power grids in the world. Partnering with about a hundred clients, the nonprofit public benefit corporation is dedicated to the continual development and reliable operation of a modern grid that operates for the benefit of consumers.