After the toilet first broke down last week, the station's crew replaced its pump with a spare they had on board.

NPR: Space Toilet Awaits Repair Mission

Nearby, a decrepit tractor and an ancient pump stand idle, their engines cannibalised for spare parts.

ECONOMIST: Iraq

Some PoE equipment uses spare wires in cables that link computers back to network hubs and pump power down these.

BBC: NEWS | Technology | Net-powered computer goes on show

But OPEC is split into two camps, those with spare capacity (of which Saudi Arabia controls 70%) and those that cannot pump any more oil.

ECONOMIST: Disharmony at OPEC breeds uncertainty over the oil price