By Dennis Coyne
The EIA released the latest edition of their Electric Power Monthly on Aug. 24th, with data for June 2017. With all the data for the first half of 2017 now available the half year performance of the various sectors can be assessed. As reported on the web site utilitydive.com "Coal tops gas as leading generation source in first half of 2017." PV Magazine on their news web page chose to highlight that "renewables generate (almost) as much U.S. power as nuclear during H1 2017." The highlights of the first half of 2017 include (see the YTD row of Table 2 below for data):
- Coal generated slightly more than natural gas
- Nuclear generated slightly more than all renewables
- Conventional hydro generated slightly more than wind and solar combined
- Non-hydro renewables generated more than conventional hydroelectric
- Carbon neutral and zero emission sources combined generated more than either gas or coal
Table 1 below shows the percentage change of the selected sources between 2017 and 2016 year to date (YTD), with the year on year change between June 2017 and June 2016 below (YoY).
Table 2 below shows the percentage contribution to the generation mix of the selected sources for the month of June and year to date.
In June all dispatchable base load generators, that is Coal, Natural Gas and Nuclear powered plants, continued to ramp up production to deal with the increase in demand as the peak, mid-summer demand period draws closer. As a result, despite generating some 5,700 Gwh more than it did in May, the percentage contribution from Nuclear declined to 18.84% from 19.09% in May. Another result of the increase in the total amount generated was that despite a slight increase in the absolute contribution from Solar (500 GWh), the percentage contribution declined to 2.47%, down from 2.58% in May.
The contribution from All Renewables at 17.7% fell below the 18.8% contribution from Nuclear as Wind and Hydro continued to decline and the slight increase in Solar failed to prevent the increase in output by Nuclear from outstripping All Renewables. The continued decline in the contribution from Wind also meant that, the combined contribution from Wind and Solar declined to 7.9% from 9.5% in May and the contribution from Non-Hydro Renewables fell to 9% from 10.8%. The contribution of zero emission and carbon neutral sources, that is, nuclear, hydro, wind, solar, geothermal, landfill gas and other biomass fell from 39.87% to 36.5%.
The graph below helps to illustrate how the changes in absolute production affect the percentage contribution from the various sources.
The graph below shows the total monthly generation at utility scale facilities by year vs. the contribution from solar. The left hand scale is for the total generation, while the right hand scale is for solar output and has been deliberately set to exaggerate the solar output as a means of assessing its potential to make a meaningful contribution to the midsummer peak. This year it looks like solar will take care of about nine percent of the additional peak mid-summer demand; that is nine percent of the approximately 100,000 GWh difference between the spring/autumn lows and the mid-summer peak.
The more pronounced ramp up of solar output in 2017 now appears to be a result of the unusually large increase in capacity in the second half of 2016 and is probably not just weather related since, in June the national output increased, while there was a decline in the output of the reference site in Victorville, Calif., that I compared it to in last month's report.
The graph below shows the monthly capacity additions for 2017 to date. In June more than 84 percent of capacity additions were Natural Gas. Solar and Wind added 7.8 percent and 6.6 percent respectively. Landfill Gas made a contribution of 0.17 percent and Other Waste Biomass made up 0.52 percent. Batteries made up 0.07 percent. I have added a line to indicate the total new capacity added each month to give an idea of what the absolute amounts were added from each source. In June the total capacity added was 2,701.3 MW.