Per an article that was recently published on this forum:

"Electricity can be roughly 15-25% of the cost of a pound of copper produced. Electricity powers almost everything in a copper mine – equipment, grinding mills, crushers, shovels, trucks and lights."

Everything in the last 10 years has become more energy efficient and I'm pretty sure it's not any different with mining equipment.  That also could have a very positive impact on the revised numbers (lower operating cost)

Talking about electricity, I believe there's still a lot of capacity on the powerline these days.  Maybe BC Hydro would now consider paying a portion of the infrastructure to get new customers connected? (lower capex)

MoneyK