The EIA released the latest edition of their Electric Power Monthly on February 27th, with data for December 2018. The table above shows the percentage contribution of the main fuel sources to two decimal places for the last two months and the full year 2018 (YTD).
The winter solstice occurs on December 21st, so the absolute contribution from Solar remained much lower than in the summer months falling from 5,859 GWh in November to 4,962 GWh, with the corresponding percentage contribution decreasing to 1.47% from 1.82% in November. Coal and Natural Gas between them, fueled 60.41% of US electricity generation in December, with the share from Nuclear, Wind and Conventional Hydroelectric edging up. The contribution from Natural Gas was down at 31.71%, from 33.18% in November, with the amount generated actually increasing slightly, from 106,804 GWh to 106,978 GWh. Generation fueled by coal increased from 92,738 GWh to 96,825 GWh resulting in the percentage contribution falling slightly from 28.81% to 28.7%. Nuclear generated 71,657 GWh, 12.06% more than it did it November with the percentage contribution to the total rising from 19.87% to 21.24%. The gap between the contribution from All Renewables and Nuclear started to widen with the 0.24% increased contribution from All Renewables as opposed to the 1.37% increase in the contribution from Nuclear. The amount of electricity generated by Wind increased by about 17.58%, (3,163 GWh) resulting in the percentage contribution increasing from 5.59% to 6.27%. The contribution from Hydro increased 1,554 GWh (7.01%) in absolute terms with the increase in total generation resulting in the percentage contribution increasing by only 0.14%. The combined contribution from Wind and Solar increased to 7.74% from 7.41% in November and the contribution from Non-Hydro Renewables also increased to 10.31% from 10.22%. The contribution of zero emission and carbon neutral sources, that is, nuclear, hydro, wind, solar, geothermal, landfill gas, and other biomass increased to 38.59% from 36.97% in November.
Now that the full year's data is in for 2018, below is the updated chart for the annual contribution from the various Sources. For the full year 2018, Natural Gas generated 35.14%, 7.7% more than Coal, widening the gap between the amount of electricity generated using coal and the amount generated using NG. At 27.44%, coal has made the smallest contribution to the electricity mix for a very long time and the contribution from coal is likely to shrink further with several more coal burning facilities scheduled for closure in 2019.
In the absence of the unusually high levels of rain experienced in the west over the 2016 to 2017 winter season, the contribution from hydro-electric generation fell back to just under 7% (6.98%). Hydro has only contributed more than 7% in three years since 2005, i.e. 2006, 2011, and 2017. 2018 makes it the fifth year in a row that non-hydro renewable sources have contributed more to the electricity mix than conventional hydroelectric sources and wind alone is edging closer to contributing as much as hydro, coming in at 6.58% as opposed to hydro's 6.98%. In 2016, the EIA reported, U.S. wind generating capacity surpasses hydro capacity at the end of 2016. The lower capacity factors of wind turbines result in lower overall generation from wind but, with the growth in wind capacity continuing apace, it is a matter of time before wind generates more than hydro on an annual basis. In 2017 and 2016, wind generated more electricity than conventional hydroelectric for the months of October and November, and in October 2018, wind again generated marginally more at 5.99% as opposed to 5.77% for hydro. In November 2018, wind returned to contributing less than hydro unlike the previous two years.
The fastest growing source continues to be solar PV, with the contribution from solar growing by almost 20%, a lower rate than the previous two years when it grew by almost 50%. The contribution from solar in 2018 only grew by 66.97% in comparison to 2016, so, if the trend of slowing growth in solar continues, we will see the doubling time increase from every two years to a longer period. The ten-year view of the growth of solar continues to be spectacular nonetheless. Solar contributed a mere two-hundredths of one percent to the electricity mix in 2007 and the contribution has grown to 2.3% in 2017, over one hundred times as much.
Among other things, tariffs imposed by the current US administration on Chinese imports had a negative impact on solar capacity growth for 2018. The current administration's preference for the use of fossil fuels may have resulted in policy signals that could have affected the growth of solar capacity as well. It could be seen as remarkable that solar capacity grew as much as it did, despite the less than enthusiastic support it is receiving from the current federal administration. At some point, solar capacity growth could accelerate, as module costs continue to fall to the point where electricity generated using solar PV is the lowest cost source, even for regions that do not have the excellent solar resources available in the southwestern US.
The headline of the EIA's Today in Energy page for March 6, 2018, reads, Record U.S. electricity generation in 2018 driven by record residential, commercial sales. The lead paragraph reads:
U.S. net electricity generation increased by 4% in 2018, reaching a record high of 4,178 million megawatt hours (MWh), according to EIA's Electric Power Monthly. Last year was the first time total utility-scale generation surpassed the pre-recession peak of 4,157 million MWh set in 2007. Weather is the primary driver of year-to-year fluctuations in electricity demand. The increased demand for electricity in 2018 - including record demand in the commercial and residential sectors - is largely attributable to cold winters and a hot summer."
On electricity sales to the commercial and industrial sectors, the article states:
Electricity use in commercial buildings is also affected by the weather but to a lesser degree; electricity sales to the commercial sector last year increased 2% from 2017. Electricity use in the industrial sector has been relatively unchanged in recent years, with 2018 electricity sales to this sector 3% lower than in 2017."
This means that the increased electricity demand for 2018 cannot be attributed to any increased economic activity since, most of the increase in demand was a result of hot weather and came from the residential sector, with only a slight increase in demand from the commercial sector.
Most of the additional demand was satisfied with electricity generated by natural gas. The graph below shows the total annual generation from 2005 to 2017.
Monthly data continued
The graph below shows the absolute production from a selection of the various sources as well as the total amount generated (right axis).
The chart below shows the total monthly generation at utility scale facilities by year versus 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. In December 2018, the output from solar continued its decline heading into the winter solstice.
The chart below shows the total monthly generation at utility scale facilities by year versus the combined contribution from wind and solar. The left-hand scale is for the total generation, while the right-hand scale is for combined wind and solar output and has been deliberately set to exaggerate the combined output of solar and wind as a means of assessing the potential of the combination to make a meaningful contribution to the year-round total.
The chart below shows the percentage contributions of the various sources to monthly capacity additions for 2018. In December, 39.07 percent of capacity additions were Natural Gas. Solar added 17.16 percent and Wind contributed 42.73 percent of new capacity. Batteries had relatively minor capacity addition of 0.54 percent, 0.49 of capacity additions were Geothermal, and 0.013 percent of new capacity was hydroelectric. In December, the total added capacity reported was 8972.8 MW, more than twice as much as the amount reported in May, the next highest monthly figure. I suspect that not all this capacity was added in December but, it may be that amounts that are reported late or for which a precise commissioning date is not available, are reported in December.
For the complete year, 61.62 percent of the added capacity was Natural Gas (19305.6 MW), 21.13 percent was Wind (6621.5 MW), 15.71 percent was Solar (4921.7 MW), 0.568 percent was Batteries (177.8 MW), 0.431 percent was Hydro (135.2 MW), 0.192 was Geothermal (60 MW), 0.17 percent was Other Waste Biomass (53.4 MW), and all other sources contributed less than 0.1 percent each to the capacity additions. It is worthy of note that no new coal-fired capacity was reported in 2018.
The chart below shows the percentage contributions of the various sources to monthly capacity retirements for 2018 and the whole year. In December, 64.57 percent of capacity retirements were fueled by coal and 35.12 percent were fueled by natural gas. Conventional Hydroelectric, Geothermal, and Other Waste Biomass made up the remaining 0.31 percent of the 2541.1 MW reported retired in December.
For the entire year, 68.87 percent of the retirements were Coal-fired plants (12907.2 MW), 25.21 percent were fueled by Natural Gas (4724.8 MW), 3.24 percent were fueled by Nuclear (607.7 MW), 1.19 percent were fueled by Petroleum Liquids (222.9 MW), 0.55 percent of the capacity retirements came from Wood Waste Biomass (102.3 MW), and all other sources retired less than seventy megawatts of capacity
Following the posting of the November edition of this report, a request was made for a graph that better represented the scale of the capacity additions and retirements. Below is a chart for monthly net additions/retirements and another for the year to date.
Below is a table of the top ten states in order of coal consumption for electricity production for December 2018 and the year before for comparison.
Editor's Note: The summary bullets for this article were chosen by Seeking Alpha editors.