The free-market think tank R Street Institute is looking to defend the federally overseen electricity markets from coal and nuclear power plant owners looking for incentives to continue operating in a market dominated by low-cost natural gas.

R Street described the effort in a lengthy letter sent Wednesday to Kevin McIntyre, the Republican chairman of the Federal Energy Regulatory Commission, the nation’s top grid watchdog. The group is urging the chairman to be vigilant in defending the grid against interests looking to resurrect something akin to Energy Secretary Rick Perry’s grid plan to provide market incentives for coal and nuclear power plants.