Surry County supervisors will hold a public hearing next month on a proposed natural gas project.

Align RNG, a joint venture of Dominion Energy and Smithfield Foods, wants to build a regional facility off Route 31 that would turn methane from hog manure into pipeline-quality natural gas.

TRC Environmental Corp. has requested a conditional use permit on behalf of Align for the agricultural-zoned, 22.8-acre parcel at Surry’s border with Sussex County. Surry’s Planning Commission gave the project a favorable recommendation in November over the objection of nearby residents who took issue with the proposed facility’s sulfur emissions when the advisory body held its own public hearing on the matter. The Board of Supervisors has the final say on the requested permit.

When hog manure breaks down, it emits methane, a component of natural gas that’s also a greenhouse gas. Currently, this methane is emitted into the atmosphere, but according to company officials, it can be captured through the use of an anaerobic digester and covered lagoons – and piped to the proposed regional facility for processing.

The Surry site would serve as a hub for participating Smithfield Foods farms in Sussex, Surry, Isle of Wight and Southampton counties. There, the collected gas would pass through membranes to remove hydrogen sulfide and carbon dioxide, leaving a 99% pure product that can be fed into an existing natural gas pipeline near the site.

According to Align, the reduction in greenhouse gases from participating farms would be roughly equivalent to taking 22,000 vehicles off the road. That said, the extracted carbon dioxide would be re-released, and not all of the extracted hydrogen sulfide would be turned into solid sulfur and hauled away. A small amount that escapes the membranes would be fed into a thermal oxidizer – essentially an incinerator – where intense heat would transform the gas into less-harmful sulfur dioxide and re-release it into the atmosphere.

Company officials estimate the facility would emit just over 8 tons of sulfur dioxide and 12 tons of carbon dioxide annually. Align plans to sell the environmental attributes associated with the facility, which it considers to have a “net negative” carbon footprint despite the re-released gases since the methane it would keep out of the atmosphere is a far more potent greenhouse gas.

According to Align spokeswoman Lucy Rhodes, the sale of the facility’s environmental attributes would operate much in the same way as when electricity-generating facilities sell renewable energy certificates to companies seeking to decrease their overall carbon footprints.

The supervisors’ April 7 meeting, which will include the public hearing, will begin at 7 p.m. in the general district courtroom of the Surry government complex at 45 School St.