Garbage In, Gas Out: Hopkins Is Open

Every ton of trash buried at a landfill keeps producing gas for decades after the truck drives away.

At the Hopkins County landfill in western Kentucky, that gas used to have two options: burn off in a flare, or vent. Now it has a third: become pipeline-quality renewable natural gas.

The Hopkins Facility, a turnkey landfill gas-to-RNG plant ESI designed, built, and commissioned for the landfill’s owner, has celebrated its grand opening and closed out its first full month of commercial operations, delivering RNG into the local pipeline, on schedule, within a single day of its contractual completion date. Here’s the story behind the numbers.

From Flare Gas to Pipeline-Grade Fuel

Raw landfill gas is a rough product: only about half of it is methane. The rest is carbon dioxide, nitrogen, oxygen, moisture, and sulfur compounds; nothing a pipeline will accept. The Hopkins facility pulls gas from the landfill’s existing collection system, which previously sent it to an open flare, and runs it through membrane separation and adsorption processes until it reaches pipeline-grade specifications. From there, it’s injected directly into the existing local natural gas pipeline.

The plant is currently processing approximately 3,500 standard cubic feet per minute (scfm) of inlet landfill gas, but it was designed with future growth in mind. The facility is built to accommodate up to 5,000 scfm as the landfill’s gas production increases, providing room to grow without outgrowing the plant.

A Turnkey Build, Start to Finish

ESI’s scope at Hopkins covered the entire chain: analyzing the landfill’s well-field gas, designing the plant around its volume and chemistry, procuring the equipment, building the facility, commissioning it, and proving performance, all under one contract. Process engineering, mechanical engineering, controls and programming, and piping design all stayed in-house.

The project ran a roughly two-year arc from award to first gas, with custom equipment on lead times of up to 65 weeks and a 90-day startup phase that coordinated commissioning crews from 15 to 20 equipment vendors while gas quality was checked continuously on both sides of the utility interconnect. Hopkins was delivered in parallel with a second ESI-built RNG facility for the same owner, hundreds of miles away, and both came in on schedule.

Handover wasn’t the finish line, either. The owner chose to operate Hopkins with its own team, and ESI is on site now under a six-month support agreement, training that team to run the plant.

Hopkins at a Glance

•      Location: Hopkins County Regional Landfill, western Kentucky
•      Scope: turnkey design, procurement, construction, commissioning, and operator training by ESI
•      Capacity: 5,000 scfm of inlet gas
•      Process: membrane separation and adsorption to pipeline-grade RNG, injected into the existing local pipeline
•      Alternative: the landfill’s gas collection system previously routed this gas to an open flare
•      Schedule: delivered within one day of the contractual completion date
•      For ESI: the ninth RNG facility the field team has delivered, with two more currently under construction