Many WUWT might think that renewable energy just can’t cut it, and when it comes to certain demand situations that may be a very valid issue. However, there has been quite a surge in installed renewables for daytime generation in California over the last 6 years, and the numbers from CAISO do tell a story that is surprisingly positive. Engineer and attorney Roger Sowell explains more about this month in this guest post. -Anthony
Guest essay by Roger E. Sowell, Esq.
From CAISO, record-setting renewable production
A lot of good is being done by renewable energy power plants in California, especially with the Aliso Canyon gas storage facility at very limited capacity due to an earlier leak. Renewable power plants are preventing the grid from experiencing blackouts.
The graphic above, from California Independent System Operator, CAISO, shows renewable power production for what appears to be the record-setting date thus far, June 14, 2016. Total renewable energy was 211,546 MWh. Yesterday, June 22 was not far behind with 208,949 MWh.
Today, June 23’s results are shown below, not quite a record but still a bit more than 200,000 MWh from renewables. see link to CAISO archives on renewable output.
Renewables on June 14 provided an average of 33 percent of the 24-hour total system demand. On an hourly basis, renewables provided 46 percent of the load at 3 p.m. that day. The load on the grid peaked at approximately 39,500 MW just before 6 p.m. Solar production peaked at approximately 7,400 MW.
These results are higher than the peak production in 2015, which was 189,000 MWh in a 24 hour period. As could be expected, peak production occurs when solar power is at or near the Summer Solstice, June 20th typically, but also when wind production is greatest. Wind production was at a maximum thus far at 92,000 to 93,000 MWh in the first half of 2016. On June 14th wind provided 92,250 MWh. Typically in California, wind production peaks in June or July then decreases for the remaining months (source, EIA).
Renewables for June 23, 2016
showing Solar PV exceeds 7,000 MW
and total Renewables exceeds 200,000 MWh
The renewable energy produced saves the state from burning natural gas in the gas-fired power plants, which is a very good thing as this summer’s loads must be met without the full production of stored gas from Aliso Canyon. How much gas is not burned is somewhat difficult to estimate because one must know which gas-fired power plants are not being run and their respective heat rates. Also, as some gas-fired plants are no doubt operated at a slightly reduced rate, one must know the heat rate for each power plant at the reduced output. Reduced output from selected plants is advisable to allow rapid power increase to compensate for variations in the renewable production due to clouds, and changes in wind speed.
However, an estimate of the natural gas not burned can be made by taking the total renewable output from wind and solar, 167,950 MWh on June 14 (per the table at the top of the article), and using an average of 45 percent thermal efficiency for the power plants not being run. On that basis, approximately 1.3 billion cubic feet of natural gas was not burned on that day. Per California Energy Commission documents, that is nearly the same gas withdrawal rate at Aliso Canyon when it is at full operation (1.9 billion cubic feet maximum withdrawal). See Table 1 in “Aliso Canyon Action Plan to Preserve Gas and Electric Reliability for the Los Angeles Basin,” see link
The state’s ability to produce renewable power has changed dramatically since the San Onofre Nuclear Generating Station (SONGS) was taken off-line suddenly in 2012 as shown in the graph below:
As shown in the figure and California Energy Commission’s page (see link), solar PV capacity grew from 214 MW at the end of 2011 to 5,498 MW at the end of 2015. More capacity has been added so that, as above, solar PV now can produce approximately 7,000 MW. Solar thermal recently has exceeded 700 MW peak.
It is especially ironic that renewables, once derided as destabilizing a grid, are now riding to the rescue and helping to prevent blackouts on the California electric grid during summer heat waves. One can only imagine the rolling blackouts and uproar with Aliso Canyon gas storage effectively out of commission, SONGS nuclear generating shut down, and if no renewable power plants had been installed over the past 5 years.