Northern Border natgas pipe heat content too high due to Bakken ethane -EIA

May 14 (Reuters) - Northern Border Pipeline said ethane accounted for more than 14% of the volume of natural gas moved on the pipeline, causing the heat content to rise above the upper limit on most gas pipes, the U.S. Energy Information Administration said late Thursday.

Northern Border said the rise in heat content is occurring more often as more gas on the pipe comes from the Bakken Shale in North Dakota, where gas is ethane rich.

Gas from Canada, where more of the fuel carried in the pipe was sourced in the past, is lower in ethane.

Ethane is a natural gas liquid that can be sold as ethane or mixed with methane in a gas pipe. Natural gas is mostly methane.

Higher gas heat content can cause operational issues for gas customers, and it makes delivering gas to interconnecting pipelines more challenging because most pipelines have heat content limitations.

Northern Border, owned by units of Canadian energy company TC Energy Corp (50%) and U.S. energy company Oneok Inc (50%), said it continues to investigate options to implement a 1,100 British thermal units per cubic foot (Btu/cf) upper limit on gas heat content to address these issues.

Heat content is measured in Btu/cf and 1,100 Btu/cf is the upper limit on most U.S. gas pipes.

Northern Border's previous filings for a gas-quality tariff with the U.S. Federal Energy Regulatory Commission (FERC) in May and August of last year were rejected, EIA said, noting FERC encouraged Northern Border to continue working with its shippers to develop a proposal to address operational concerns.

The 1,412-mile (2,272-km) Northern Border connects gas reserves in Western Canada with consumers in the U.S. Midwest. It also receives and transports U.S.-produced gas from regions like the Bakken. (Reporting by Scott DiSavino; Editing by Hugh Lawson)