Nuclear power is a "loopy" fad and a "weapon of mass distraction" for the Morrison government's backbench, if you believe former prime minister Malcolm Turnbull.

Australia's former leader has expressed the view on Twitter, in a discussion about the coalition being in line to hit its 2020 renewable energy target.

"I am delighted the target has been met - but I never had any doubt it would be - the challenge now is making sure the storage/firming is in place to make the renewables reliable," he wrote on Thursday night.

He said ensuring such reliability will require "careful planning and provision".

But he stressed renewable energy has an edge over coal and "loopy" nuclear power.

"The bottom line is renewables + storage are cheaper than new coal let alone the loopy current fad of nuclear power which is the current weapon of mass distraction for the backbench."

The comments come after Labor urged Prime Minister Scott Morrison to reject the "fantasy" of nuclear power in Australia, saying it's three times more expensive than other options and would take decades to be up and operating.

A parliamentary committee is looking at whether nuclear is a feasible, suitable and palatable solution for Australia's future energy needs.