US Energy Secretary Rick Perry on Friday said his recent proposal that coal and nuclear plants be subsidised for keeping on-site fuel stocks was intended to spark a “conversation”, while pointing to support for renewables as evidence that there’s “no free market” in the US energy industry.

Last week Perry sparked a firestorm by requesting the Federal Energy Regulatory Commission (FERC) rapidly create a set of rules that would allow coal and nuclear plant operators in wholesale markets to recover their costs and make a profit regardless of market conditions, because of their ability to maintain a 90-day supply of fuel on site.