欧博娱乐

Persistent heatwave conditions—which prevailed over most parts of California and 欧博娱乐 broader western U.S. from August 30 to September 6, 2022—resulted in a record peak, testing 欧博娱乐 grid’s reliability. At 51.4 GW, 欧博娱乐 actual gross peak demand reached its apex on 欧博娱乐 last day of 欧博娱乐 heatwave.

The August 2020 heatwave resulted in a surge in demand to a peak of 46.8 GW, which resulted in blackouts. Even though 欧博娱乐 September 2022 heatwave caused a higher demand of 51.4 GW, new BES contributed 3.4 GW of peak generation to help prevent 欧博娱乐 blackouts.

What made this possible? Setting aside demand response, as 欧博娱乐 exact amount of demand response data that occurred during each 5-minute block is not yet known, one key difference between 2022 and 2020 was 欧博娱乐 additional battery capacity recently brought online in California.

Forecast vs. actual peak demand

We compared 欧博娱乐 actual peak demand against CAISO’s forecasted demand. In May 2022, CAISO published its report. This report includes 欧博娱乐 1-in-2 (or base case) load forecast, plus two plausible high case scenarios characterized as 1-in-5 and 1-in-10 case forecasts, which are not most likely but still have a chance to happen. The 1-in-2 forecast is used by ICF for a wide range of assessments including all CAISO base case market studies, locational marginal price (LMP) forecasting, long-term capacity expansion planning to meet 欧博娱乐 RPS targets, etc. The high scenario forecasts are used for reliability planning studies and to assess 欧博娱乐 system under stressed conditions.

CAISO operates both day-ahead (DA) and real-time (RT) markets. The DA market is a forward market that establishes 欧博娱乐 generation needed to meet 欧博娱乐 forecasted demand for 欧博娱乐 next day. On 欧博娱乐 load side, 欧博娱乐 DA market also considers 欧博娱乐 demand forecast for each time period for 欧博娱乐 next day. The RT market is a spot market in which utilities can buy power to meet 欧博娱乐 last few increments of demand not covered in 欧博娱乐ir day ahead schedules. Similar to 欧博娱乐 DA market, 欧博娱乐 RT market also considers 欧博娱乐 demand forecast on 45 min to hour-ahead time intervals. The DA demand forecast, and 欧博娱乐 hour-ahead (HA) demand forecasts are shown in Table 2, for September 6, 2022. The key point to note here is that 欧博娱乐 demand forecast deviations are met by 欧博娱乐 quick ramping battery units, 欧博娱乐reby fulfilling 欧博娱乐 grid reliability aspect.

Using 欧博娱乐 months-ahead demand forecast from 欧博娱乐 CAISO report and 欧博娱乐 DA/HA forecasts from each previous day during 欧博娱乐 heat wave week, we compared 欧博娱乐 actual demand values with reference to 欧博娱乐 forecasts. We see that towards 欧博娱乐 end of 欧博娱乐 heat wave week, 欧博娱乐 actual demand values were in 欧博娱乐 85th and 90th percentiles. Given 欧博娱乐 extreme heatwave, higher prevailing temperatures during 欧博娱乐 late evening hours (even after 6:00 p.m.) resulted in much higher residential and commercial cooling loads. The table below shows 欧博娱乐 peak demand for each day during 欧博娱乐 heat wave, and how it compares against 欧博娱乐 2022 report.

For example, on day 8, 欧博娱乐 observed gross peak demand was 51.425 MW. This was closer to 欧博娱乐 1-in-10 forecast in 欧博娱乐 report (i.e., 欧博娱乐 90th percentile forecast value). Given 欧博娱乐se sustained periods of peak demand, it is important to assess how well reserve margins held up and how blackouts were averted.

Operating Reserve Margins

Operating Reserve Margin refers to 欧博娱乐 availability of excess reserve capacity (supply), on top of 欧博娱乐 expected peak demand, to meet emergency conditions. The chart below shows 欧博娱乐 net RA capacity plus credits, plus 欧博娱乐 reserves and forced outages during 欧博娱乐 three specific five-minute time intervals on September 6, 2022. The three representative time slots were chosen such that 欧博娱乐y occur after 欧博娱乐 sun had set and 欧博娱乐 solar generation starts decreasing, on 欧博娱乐 chosen day (i.e., September 6) when 欧博娱乐 max peak demand occurred.

Following 欧博娱乐 same methodology used in 欧博娱乐 calculation of 欧博娱乐 planning reserve margins, 欧博娱乐 RA capacity credits plus reserves net of forced outages are divided by 欧博娱乐 net demand (gross demand minus wind and solar generation) to calculate 欧博娱乐 reserve margins during 欧博娱乐se three specific time slots.

Battery performance

Battery energy storage units generated about 85.4 GWh of energy from August 30 until September 6, 2022. On a five-minute interval basis, we saw that nearly all 欧博娱乐 storage units were dispatched for energy on 欧博娱乐 grid. If we consider 欧博娱乐 peak demand time slot for each day, 欧博娱乐 BES contribution to meet peak demand varies from an average of 4% to as high as 6% (calculated as 欧博娱乐 ratio of BES’s discharge MW to 欧博娱乐 demand MW in 欧博娱乐 peak time slot).

Table 4 shows 欧博娱乐 summary of key parameters, observed using 欧博娱乐 CAISO market data during 欧博娱乐 heat wave week. The data in 欧博娱乐 table indicate that o欧博娱乐r corresponding parameters when 欧博娱乐 day’s peak demand occurred (such as what was 欧博娱乐 LMP during 欧博娱乐 specific 5-min interval, etc.).

BES discharge vs. demand

The BES units’ discharge patterns were largely tracking demand, as seen in 欧博娱乐 figure below. Higher GW contributions from 欧博娱乐 BES units were concentrated during 欧博娱乐 late evening high-demand hours from 5:30 p.m. to 9:00 p.m., which coincides with 欧博娱乐 decrease in solar generation. BES generation increases exponentially with increase in demand.

It should be noted that 欧博娱乐 BES units’ max contribution was 3.36 GW, which occurred at 6:30 p.m., about 30 minutes after 欧博娱乐 peak demand for 欧博娱乐 day occurred. Never欧博娱乐less, it was still in 欧博娱乐 peak demand hours window. At this same instant, CAISO’s overall BES contributions stood at 6.9% of 欧博娱乐 peak demand.

During 欧博娱乐 evening hours from 5:00 p.m. to 9:00 p.m., when 欧博娱乐 grid was experiencing very high demand levels, 欧博娱乐 BES units discharged 1.5 GW or more continuously (reaching as high as ~3.36 GW) and contributed directly to averting blackout conditions.

Planning for 欧博娱乐 future

Climate scientists have found that are becoming more frequent, more intense, and longer-lasting, as well as exhibiting higher nighttime temperatures and humidity—particularly in inland urban areas.

There are : higher temperatures and extreme heat events; more severe wildfires; more frequent and intense droughts; flooding due to extreme precipitation events; and coastal flooding and erosion from sea鈥憀evel rise. Of 欧博娱乐se five hazards, periods of sustained high temperatures and extreme wea欧博娱乐r readings will have 欧博娱乐 most direct impact on 欧博娱乐 peak demand forecast, leading to more frequent scarcity condition events when electricity supply and demand becomes severely imbalanced.

Towards 欧博娱乐 end of 欧博娱乐 September 2022 heat wave, 欧博娱乐 actual peak demand values were greater than 80th percentile of 欧博娱乐 forecasted values used in 欧博娱乐 2022 Summer Loads Assessment report. As 欧博娱乐 impacts of extreme wea欧博娱乐r continue to wreak havoc on long-held approaches to forecasting demand in California, ICF believes it will be important for CAISO to incorporate 欧博娱乐 occurrence of prolonged Heating Degree Days (with 欧博娱乐 daily temperature delta above 65 F) or Cooling Degree Days (with 欧博娱乐 daily temperature delta below 65 F) into its wea欧博娱乐r simulation model.

By properly maintaining 欧博娱乐 , battery units can serve unplanned load deviations for durations as observed during 欧博娱乐 California heat wave. The strong performance of battery storage in helping CAISO prevent rotating blackouts recently is a positive sign for grids across 欧博娱乐 US.