Shell’s mobile drill rig left Captains Bay yesterday evening and is now making its way to Seattle for technical upgrades.

According to Shell spokesperson Curtis Smith, modifications to the Kulluk are expected to cost tens of millions of dollars, and the goal is to lower the rig’s emissions by 90 percent. The modifications to the Kulluk are expected to take ten months.

The Kulluk is a major part of Shell’s Arctic exploration plan for next year. The company was originally slated to use the rig as a back-up relief well unit in the event of a blowout. But now, the Kulluk and the drill ship Noble Discoverer will be used to drill wells in the Chukchi and Beaufort seas should Shell get approval from the federal government. Shell’s arctic drilling plan was held up this year after the company was unable to secure air permits.