Best refinery coolant for a frosty map?

Looks like nectar will boil in the pipes (though it looks like an amazing substitute for polluted water for keeping my base frosty with an atst).

I'm trying to do this without visiting the other planetoid, so no direct access to petroleum.

Am I going to have to resort to melting plastic into naphtha? I've always sucked at melting plastic without getting sour gas... :(