CALGARY, Alberta - TransCanada Corp is offering crude oil shippers extra space on its Keystone pipeline from Alberta to the U.S. Gulf Coast after technological improvements freed up 10,000-15,000 barrels per day (bpd) of capacity, the company said on Friday. The overall capacity on the 590,000 bpd Keystone pipeline has not changed, but the company will be able to increase daily volumes, said TransCanada spokesman Mark Cooper. “This is essentially some operating efficiencies that we have been able to find through technological advancements to allow us to contract out more volume,” he said. He declined to say what Keystone’s current daily volumes are. Interested shippers will have until Sept. 12 to submit bids for the extra space. The 4,200-kilometer (2,610-mile) Keystone line carries light and heavy crude from the marketing hub of Hardisty, Alberta, and delivers to Illinois, the U.S. crude futures hub of Cushing, Oklahoma and Port Arthur, Texas. Around 90 percent of capacity on the pipeline is reserved for committed shippers, with the remainder available for spot volumes.