Mid-Atlantic grid operator PJM has modeled a future with more wind and solar power, cheap natural gas, and retiring nuclear and coal power plants -- integrated under projected peak conditions and in hypothetical heat waves and cold snaps -- and found that this increasingly diverse generation mix doesn’t threaten grid reliability, at least in the near term.
The model sets an upper bound of about 20 percent on how much renewable energy -- wind, namely -- that the 13-state transmission grid operator can take, before reliability issues start to arise.
PJM’s analysis of reliability and fuel diversity (PDF), released Thursday, is among many across the country tackling the challenge of integrating intermittent renewable resources into the grid. In PJM’s case, however, it was triggered mainly by the growth of natural gas as a primary generation fuel, raising the question of whether that resource is reliable enough to replace retiring coal-fired and nuclear power plants.
PJM’s resource mix has changed rapidly over the past decade. In 2005, coal and nuclear resources generated 91 percent of its electricity. But over the past six years, those figures have dropped to 33 percent for coal and 18 percent for nuclear, while natural gas has grown to represent 33 percent of the power mix.
Meanwhile, renewables including hydro made up 6 percent of PJM’s 2016 generation mix. Demand response, which had accounted for roughly the same amount of capacity as renewables as recently as 2015, has shrunk a bit in the past two years after PJM implemented new capacity performance rules.
