Engineering costs, inspection costs, a lot of stainless steel tanks and tubing, a lot of stainless steel valves/clamps/misc attachments, a lot of stainless steel welding that needs to be certified, redundant failsafes, various safety devices/monitoring systems, etc. I'm sure some bribes are buried/hidden in these costs as well, such as if you allow this oil refinery we'll use your construction company and you can over charge us so any payoff is legal.