The PJM Interconnection (PJM), Mid-Continent ISO (MISO), and Southwest Power Pool (SPP) report the highest shares of coal-fired generating capacity among Regional Transmission Operators (RTOs) and Independent System Operators (ISOs) through 2014, according to a recent report from the Federal Energy Regulatory Commission (FERC).
FERC released a report on Aug. 12 that examines the performance and benefits of RTOs and ISOs. The initiative arose in response to a 2008 Government Accountability Office (GAO) report recommending that FERC do more to track the performance and benefits of RTO and ISO markets.
Coal-fired generators accounted for the largest share of installed capacity in PJM from 2010-2014, ranging from a high of 42% in 2011 to a low of 39.7% in 2014. MISO reports that coal-fired generating capacity represented the largest share of generating capacity from 2010-2012, prior to the integration of MISO-South.
The share of natural gas and oil-fired capacity in MISO increased significantly, from 31.3% in 2010 to 41.7% in 2014, as a number of utilities in the Gulf Coast region joined MISO in December, 2013.
In the process, MISO transitioned from a majority coal-fired capacity mix in 2010 to a majority natural gas and oil-fired capacity mix in 2014. The New York ISO (NYISO) also reported that the New York Control Area has become increasingly dependent on natural gas and dual-fuel generating units, although the share of natural gas and oil-fired generation increased modestly in NYISO, from 60.7% in 2010 to 61.2% in 2014.
Among RTOs and ISOs, the California ISO (CAISO) and NYISO report the largest shares of renewables and hydroelectric generating capacity.
As of 2014, renewable and hydroelectric generators represented 36.5% of capacity in CAISO and 20.2% of capacity in NYISO. The largest relative increase occurred in SPP, where the share of renewable and hydroelectric capacity increased from 6.9% in 2010 to 12.6% in 2014.