When you turn up the thermostat on your furnace, the burner simply ignites. But that mundane act is only possible because of a national network of natural gas wells, pipelines, storage facilities, and the enormous gas compression engines that power it all.

Mechanical engineering Professor Daniel Olsen will lead a project to reduce methane emissions from the large engines that power natural gas compressors, under a $1.5 million grant from the Department of Energy’s Advanced Research Projects Agency, or ARPA-E.

The grant is part of ARPA-E’s $35 million REMEDY program, targeting methane emissions in coal, oil, and gas industries. Methane is 25 times as potent as carbon dioxide at trapping heat in the planet’s atmosphere and contributing to climate change. That makes these emissions a priority for researchers and regulators.

Recapturing lost fuel

Pipeline engines both burn natural gas, and compress it so that it can be delivered to the utilities that serve our homes. They run around the clock, every day of the year. And they are one of the front lines in the battle against climate change.

As these essential and efficient workhorses run, a small amount of methane and other combustion byproducts escape from the combustion chambers with each engine revolution. The methane and other gases leak past the piston rings into the crankcase, where they are eventually vented into the atmosphere. Between these losses and incomplete combustion, some 2-5% of the methane is emitted, depending on the age of the engine.

“You always have ‘blow-by’ flow, even in a new engine,” Olsen said. “But an engine that’s worn out, near end of life, might have twice as much.”

Olsen’s group will be working to build a system to capture crankcase gases, filter them, and feed the methane back into the engine to be burned on the following cycles. The system should eliminate blow-by losses entirely. It’s a rare win-win in the world of climate change, saving producers money while reducing emissions.

David Montgomery, an adjunct professor at CSU and Manager and Technical Steward in the Engine Research Department at Caterpillar (a partner in the program) commented, “This is an important facet of Caterpillar’s ongoing effort to help customers meet their operational efficiency and sustainability goals. Another important aspect of the technology is that it can be applied to existing engines as well as new engines.”

Can’t stop, won’t stop

It won’t be simple. Recirculating crankcase gases can cause increases in emissions, sooty deposits, and intake icing. That spells trouble when downtime can mean service interruptions for consumers, and lost revenue for producers.

The new system will have to separate contaminants from methane and other gases to avoid those impacts. It’s a difficult challenge and explains why crankcase gases on these engines are traditionally vented to the atmosphere for reliability reasons.

“The engines on natural gas pipelines have to run 24/7,” Olsen said. “The filtration system is critical.”

Partners in industry

When the grant was awarded, the group needed an engine to work with. The fastest and most sustainable way to get an engine was to overhaul and update an existing engine from the field.

Luckily, an industry connection came through. Western Midstream had a suitable engine that was due for a overhaul and offered it as an in-kind donation. Caterpillar had their dealer Wagner Equipment Co. do a full overhaul on the engine, and reconfigure it to match a new model. It was delivered to Colorado State University’s Powerhouse Energy Campus in April.

“Having the engine used in this program sourced in a sustainable process (remanufacturing an existing engine) makes the sustainability message of this program come through even stronger,” said Montgomery. “This engine will provide a great research facility, ready to provide further pathways to methane reduction for years to come.”

With the engine in place, Olsen, co-investigator Bret Windom, and their team of CSU graduate and undergraduate researchers now turn to the work of developing the filtration and recirculation system. When it’s ready for trials, Western Midstream has offered the use of a production engine at one of their field sites for emissions and durability testing.

Olsen said the recirculation equipment developed under this grant could be in an initial field demonstration as early as 2024. When the systems become commercially available, cuts to domestic methane emissions are expected to help mitigate climate change impacts from the natural gas economy. It’s something to think about the next time you’re basking in the warm comfort of natural gas heat on a cold, Colorado winter day.