Wow. I didn't realise it until I read
this, but a double dissolution would absolutely rape the Coalition. Namely, quota in a DD is only 7.7%.
That means a Greens senator in every state on the Green primary vote alone, 2 in Tasmania, and even one in the ACT! (but not NT). On top of that, they'd manage 1 or 2 more from Labour preferences in Vic and NSW (SA would probably go to Xenophon).
On top of that, the Liberals would lose the 'lag' Senators they gained during Howard's boom years in 2004.
If we take Labour at 34, Greens at 10 (min), and 1 independent, that leaves the Coalition with maybe 31 Senate seats maximum. Labour is marginally better off here because they'd no longer need to negotiate with Xenophon or Fielding if they had Greens support, though their biggest gains come in the House (where, ironically, such gains are least useful).
Turnbull should make it his sole aim as Liberal leader to avoid a DD.