TransCanada Corp. gave natural gas shippers a promise Thursday that the proposed partial conversion of its Mainline to oil service will only proceed when all their firm transportation requirements are fulfilled.

The pledge figured in regulatory filings for a C$13.5 billion (US$12 billion) overhaul and expansion of the natural gas and oil pipeline network that the Calgary company announced in two provincial capitals: Toronto and Quebec City.

TransCanada filed three applications to the National Energy Board (NEB): one for the C$12 billion (US$10.7 billion) oil conversion project called Energy East, and associated asset transfer; and a new C$1.5 billion Ontario-Quebec gas conduit called Eastern Mainline.

Although the projects have been repeatedly announced, TransCanada took the regulatory step with great fanfare because the package has become a national rallying point for industry and government supporters. The same goes for environmental and native protesters.

The political divisions escalated, with all sides swiftly taking stands.

Alberta Premier Jim Prentice issued a statement saying, “The Energy East Pipeline represents a true nation-building project. Today’s application for approval is a significant step towards getting full market value for Canada’s resources, and will help the country realize its economic potential.”

Prentice added that energy production from the Quebec hydroelectric dam to Alberta bitumen “needs to get to markets. Alberta supports all safe and viable options to diversify and expand market access for Canada’s resources.”

Greenpeace and Environmental Defense Fund fired off news releases and a report accusing TransCanada and its supporters of mounting a misleading, global-scale “marketing ploy” for the northern Alberta oilsands, known as “dirty oil” among environmentalists.

The Canadian protesters picked up ammunition from the opposition side of the battle over TransCanada’s stalled Keystone XL pipeline project in Washington, DC, from Oil Change International and the Institute for Energy Economics and Financial Analysis.

The green pair released a report claiming that oilsands developers lost US$30.9 billion in 2010-2013 due to project cancellations and delays, and that “a fierce grassroots movement against tar sands development” deserves credit for 55%, or US$17 billion, of the damage.

Energy East has also been a sore spot since its initial announcement about three years ago between TransCanada and the country’s top three gas distribution companies: Union (Spectra) in southern Ontario, Enbridge in the Toronto region and Gaz Metropolitain in Quebec.

A settlement on co-operative gas capacity additions in Ontario and Quebec, now awaiting NEB approval, excluded effects of Energy East because they were unknown at the time the deal was made.

Gaz Metro last week fired the first shot in a forthcoming regulatory battle by calling for TransCanada to absorb all costs of replacing eastern gas service lost in the oil conversion. Union and Enbridge were reviewing the package and considering positions to take.

In its NEB filings TransCanada says all Ontario and Quebec requirements for firm gas transportation service, as shown by open season capacity auctions, have been covered by the Eastern Mainline project.

The new line would open with room to carry 600 MMcf/d from storage and trading facilities in the Union region east for 250 kilometers (156 miles) to Iroquois, the last Ontario stop and entry point into the northeastern United States before Quebec’s western boundary.

The application for NEB approval of the asset transfer for the Energy East oil conversion says, “TransCanada will proceed…only when sufficient capacity is available to continue meeting its firm service requirements.”

Tolls will remain open for review and approval after the transfer, the filing adds. TransCanada predicts shippers will eventually save C$950 million (US$845 million) due to combined effects of reducing excess capacity on western legs of its Mainline and providing new eastern service options, especially to increase imports of U.S. shale gas.

As previously announced, Energy East includes converting 3,000 kilometers (1,864 miles) of one of six pipeline loops in TransCanada’s right-of-way between Alberta and Ontario to 1.1 million barrels per day of oil service, plus 1,600 kilometers (1,000 miles) of new pipe from Montreal to the East Coast. Shippers have already booked about four-fifths of the proposed capacity by signing 20-year transportation service contracts.

The conversion will provide Ontario, Quebec and Maritimes provinces refineries with added buy-Canadian options for their consumption of 700,000 barrels per day, TransCanada predicts. Rival Enbridge Inc.’s half-century-old national oil line already serves the region, and is nearing completion of a flow reversal to westbound of its eastern-most leg to substitute Alberta production for imports.

Although TransCanada has emphasized the potential of Energy East to satisfy Canadian oil markets, the project includes new tanker export sites near Quebec City and beside Irving Oil’s refinery, shipping and trading complex on the New Brunswick coast at Saint John.

At Thursday’s news conferences, TransCanada officials predicted about half the traffic via Energy East would be exported and that the project would set two records: longest North American oil pipeline, and Canada’s bulkiest regulatory application at 30,000 pages. Much of the documentation is environmental assessments and records of more than 18 months of consultations with 5,500 landowners and 158 aboriginal communities along the right-of-way.