The American Public Power Association released an update to its report finding that capacity markets do not incent new generation, finding that, in 2014, only 14 percent of new U.S. capacity was built within the footprint of the Regional Transmission Organizations (RTOs) with mandatory capacity markets (PJM Interconnection, ISO New England and parts of the NY ISO), despite the fact that these RTOs cover almost a quarter of the megawatt-hours consumed in that year.

"In addition, over half of the capacity built in the mandatory markets was a single plant constructed by a vertically integrated investor-owned utility," APPA said

See APPA's report here