A Guest Post by Islandboy

The EIA released the latest edition of their Electric Power Monthly on February 27th, with data for December 2017. 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 2017 (YTD).

The winter solstice occurs around December 21st so the absolute contribution from Solar remained much lower than in the summer months falling slightly from 4651 Gwh in November to 4536 GWh, with the corresponding percentage contribution decreasing to 1.31% from 1.52% in November. Nuclear generated 73700 Gwh, 10.6% more than it did it November but the increase in total generation resulted in the percentage contribution to the total remaining essentially the same. The gap between the contribution from All Renewables and Nuclear continued to widen with a 1.21% decreased contribution from All Renewables as opposed to the the 0.41% decrease in the contribution from Nuclear. The amount of electricity generated by Wind decreased by about 2%, (544 GWh) resulting in the percentage contribution decreasing from 7.6% to 6.51%. The contribution from Hydro increased 2666 Gwh (13%) in absolute terms with the increase in total generation resulting in the percentage contribution decreasing by 1.02%. The combined contribution from Wind and Solar decreased to 7.9% from 9.12% in November and the contribution from Non-Hydro Renewables also decreased to 9.5% from 10.76%. The contribution of zero emission and carbon neutral sources, that is, nuclear, hydro, wind, solar, geothermal, landfill gas and other biomass decreased to 37.32% from 38.94% in November.

Full Year Data

Now that the full year’s data is in for 2017, below is the updated chart for the annual contribution from the various Sources. For the full year 2017, Natural Gas generated 31.7%, 1.6% more than Coal, going against the EIA’s projection that Coal would generate more electricity than NG in 2017. The unusually high levels of rain in the west over the 2016 to 2017 winter season boosted the contribution from hydro-electric generation to 7.47%, the highest level since 2011 when hydro contributed 7.79%. 2017 Makes it the fourth year in a row that non-hydro renewable sources have contributed more to the electricity mix than conventional hydroelectric sources and wind alone is getting closer to contributing as much as hydro, coming in at 6.33%. Last year 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.

The fastest growing source continues to be solar PV, with the contribution from solar growing by almost 50% for the second year in a row. The contribution from solar in 2017 doubled in comparison to 2015. The more spectacular growth story comes from a ten year view of the growth of solar. Solar contributed a mere one hundredth of one percent to the electricity mix in 2007 and the contribution has grown to 1.92 % in 2017, 192 times as much. Granted, solar was growing from a very small base but, recent trends suggest that the high growth rate should be sustainable for at least another couple of years, since global manufacturing capacity is still growing.

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 it’s potential to make a meaningful contribution to the midsummer peak. In December 2017 the output from solar continued it’s decline heading into the winter solstice.

The chart below shows the total annual generation from 2005 to 2017. Except for 2009, 2017 had the least amount of electricity generated for the period. This may have been as a result of the very mild winter early in the year, followed by mild late summer temperatures but, further explanations may be needed.

The graph below helps to illustrate how the changes in absolute production affect the percentage contribution from the various sources.

The chart below shows the monthly capacity additions for 2017. In December 27.67 percent of capacity additions were Natural Gas. Solar added 27.6 percent and and Wind contributed 43.7 percent of new capacity. Batteries had relatively minor capacity addition of 0.21 percent and 0.75 of capacity additions were Geothermal. In December the total added capacity reported was 4960 MW, the highest figure for the year. For the complete year 44.73 percent of the added capacity was Natural Gas (9349 MW), 30.11 percent was Wind (6294.7 MW), 22.32 percent was Solar (4666.4 MW), 0.99 percent was Hydro (207.6 MW), 0.66 percent was Batteries (137.6 MW), 0.54 percent was Wood Waste Biomass (112 MW) and all other sources contributed less than 0.2 percent each to the capacity additions. It is worthy of note that no new coal fired capacity was added in 2017.

The chart below shows the capacity retirements for each month of 2017 and the whole year (YTD). 55.78 percent of the retirements were Coal fired plants (6263.1MW), 35.59 were fueled by Natural Gas (3996.4 MW), 6.11 percent were fueled by Petroleum Liquids (658.5), 0.92 percent of the capacity retirements came from Conventional Hydroelectric (103.8 MW) and all other sources retired less than one hundred megawatts of capacity.