Reducing emissions using innovative recapture technology

Annual emissions from the U.S. natural gas distribution system have declined 69% from 1990 to 2019, as natural gas utility companies added thousands of miles of pipeline to serve 21 million more customers, according to the American Gas Association.  At Southern Company Gas, between 1998 to 2018, we reduced annual methane emissions from our distribution system by 50% — even as the system grew by 20%.

As we work toward creating a more sustainable future by reducing greenhouse gas emissions, we continue to maintain the reliability and affordability of service that our customers need. Currently, Southern Gas Company is delivering more than 99.8% of all natural gas in our system to customers to use in homes and businesses.

We have made great progress improving the sustainability of our system. Still, we know there is more work to be done to reduce methane emissions and support Southern Company’s goal of net-zero greenhouse gas emissions in its enterprise-wide operations by 2050.

As part of our efforts to meet this goal, we utilize innovative cross-compression technologies like the Zero Emissions Vacuum and Compressor, or ZEVAC. The technology allows us to collect natural gas removed from the pipeline during maintenance or inspection and return it for use back into the line. This results in less gas or methane entering the atmosphere.  

How ZEVAC works

When a pipeline is being decommissioned, repaired or inspected, natural gas must first be removed from the pressurized pipe. In order to do this utilizing ZEVAC, we attach the inlet hose of the ZEVAC pump directly to the desired pipeline segment that we want to evacuate gas from. This takes the natural gas out of the line, allowing us to depressurize it.

Then ZEVAC transfers up to 99% of the natural gas back into the pipeline in a different location using the outlet hose. Instead of releasing natural gas into the atmosphere, we put it right back into the pipeline system. Check out this video featuring how we use ZEVAC with Integrity Verification Engineer Olivia Ward.

When we use it

Southern Company Gas’ local distribution company, Virginia Natural Gas has utilized ZEVAC to transfer natural gas, to avoid releasing it to the atmosphere, for certain projects in their operations. The technology is also being evaluated across Southern Company Gas’ other territories.

At VNG, ZEVAC is primarily used to evacuate older distribution piping systems that are being retired and replaced with new pipe. These projects might be in residential neighborhoods where reducing or eliminating vented gas is desirable. Most projects of this type consist of thousands of feet of mains and services, and ZEVAC can reduce natural gas losses as it is moved from the retired system into the new system. VNG has also used ZEVAC for pressure improvement projects and to evacuate gas from equipment before loading and unloading in-line inspection tools.

Why it is important

By using ZEVAC at Southern Company Gas we have found results of up to 99% product transfer and less than 1% methane release, showing that using this technology can benefit the environment.

We are committed to continuing to reduce our environmental footprint and are working with other members of the Our Nation’s Energy (ONE) Future coalition to support efforts to reduce methane emissions to 1% or less across the entire natural gas value chain. ZEVAC is one example of how we are using technology as part of our strategy to provide a clean, safe, reliable and affordable energy future for our customers and communities. To learn more about Southern Company Gas’ environmental sustainability efforts, visit here.