The sole reason opium was exported was because of the huge bullion deficits created by the massive imports of tea from China, with China being uninterested in any imports of its own from the West, except bullion. A lot like the current situation actually, with China holding a trillion dollars of IOU's, the modern equivalent of bullion.

Anyway, it was to even the balance of trade that the opium trade began, to stem the outflow of bullion.

Peak oil is not an energy crisis. It is a liquid fuel crisis.