A Guest Post by Islandboy

The EIA released the latest edition of their Electric Power Monthly on December 22nd, with data for October 2017. The table above shows the percentage contribution of the main fuel sources to two decimal places for the last two months and the year to date.

Nuclear generated 2078 Gwh (3%) less than it did in September but, the decrease in the total generation meant it’s percentage contribution actually increased slightly to 20.66% from 20.37% in September. A decrease in the absolute contribution from Solar from 7384 to 6810 GWh, translated to the percentage contribution decreasing slightly to 2.13% from 2.21% in September. It is worthy of note that the percentage contribution from solar was below 2% in January and February only and continues to be on target to end the year with a contribution of slightly more than 2%, in line with the increase in capacity seen over the last twelve months. The gap between the contribution from All Renewables and Nuclear narrowed slightly as All Renewables increased to 16.69% as opposed to Nuclear’s 20.66% contribution. The amount of electricity generated by Wind continued to increase, resulting in the percentage contribution increasing by 2.59%. The contribution from Hydro continued to decline in absolute terms but the decrease in total generation meant that, the percentage contribution remained essentially flat, declining by only 0.29%. The combined contribution from Wind and Solar increased to 9.89% from 7.38% in September and the contribution from Non-Hydro Renewables also increased to 11.3% from 8.63%. The contribution of zero emission and carbon neutral sources, that is, nuclear, hydro, wind, solar, geothermal, landfill gas and other biomass increased to 37.34% from 34.67% in August.

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 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. This October the output from solar continued to decline heading into the winter solstice. However, with solar capacity growing rapidly it can be expected to generate significantly more over the approaching winter season than was generated last winter, repeating the pattern of the past few years.

The graph below shows the monthly capacity additions for 2017 to date. In October 27.3 percent of capacity additions were Natural Gas. Solar added 44 percent and and Wind contributed 30.4 percent of new capacity. Petroleum Liquids and Batteries each had relatively minor capacity additions of 0.13 and 0.25 percent respectively. In October the total capacity added was 791.6 MW the fourth lowest monthly figure for the year so far, the months with lower amounts being May, August and September.