It's basically free. There's far more stuff coming from China to the west than vice-versa. A ship can't travel empty, but needs to be ballasted with an appropr

It's basically free. There's far more stuff coming from China to the west than vice-versa. A ship can't travel empty, but needs to be ballasted with an appropriate weight of cargo. If there isn't enough booked cargo on the return leg to China, they'll make up the weight with scrap metal or rubble.