CenterPoint Energy seeks to minimize methane emissions in Minnesota through new vacuum pump procedure

CenterPoint Energy is taking a unique approach to tackling methane emissions and other potential environmental and safety hazards for natural gas pipelines in Minnesota, with a procedure based on vacuum pump technology.

“A key benefit of vacuum purging is that it helps avoid methane emissions when commissioning a pipeline,” Brad Steber, CenterPoint Energy’s Manager of Technical Field Operations for Minnesota, said. “The process also limits nuisance impacts such as noise and odor, in addition to minimizing the safety risk of accidental ignition with a gas-air mixture.”

That solution purges air out of said pipelines before introducing natural gas, as opposed to the traditional method, which involved using the pressurized gas to force air out. The downside of the traditional method is that it also vents gas-laden air into the atmosphere. As methane is the main component of natural gas, and a greenhouse gas, that means flooding the air with emissions.

The system was field-tested in September on 3,200 feet of six-inch polyethylene pipe installed near St. Michael, Minnesota. This followed pressure testing of the pipe with air to guarantee its strength and gas tightness. Hoses then attached two zero emission vacuum and compressor units to an outlet on the pipeline, through which they pumped air from it until a vacuum was achieved. Once the air was removed, an inlet valve was opened and natural gas injected.

It took hours to purge the pipe, but only minutes to fill it. As a result, CenterPoint Energy intends to evaluate other vacuum pump types and test how different pipe fittings can perform under the vacuums created.