The US Department of Energy (DOE) never responded to a request from leading renewables trade groups that an important energy market study be conducted in an open and transparent manner, the groups said Tuesday.

Last month US Energy Secretary Rick Perry sent chills through the renewables industry by issuing a memo directing the DOE to undertake a study on the “long-term reliability of the electric grid”, seen by many as a potential prelude to supporting struggling US operators of coal and nuclear power plants at the expense of renewables.