Dec 2015: What would cause natural gas and crude oil to go up?
Two things would cause the price to go up.

The supply curve could move to the left: some suppliers could leave the market, some wells might switch off.

The demand curve could move to the right: new sources of demand; e.g. a burst of extremely cold weather.

This price drop is a step towards economic efficiency. You'll know when it's more efficient, because almost the whole oil &amp; gas industry will have closed apart from a few niche applications.