By Shelby Tuttle

As we become more attune to the negative effects of methane gas produced by dairy farms around the globe, technology to capture methane gas and convert it into a useful byproduct is becoming more imperative. Methane is second only to CO2 emissions from fossil fuels as a cause of global warming. Southwest Gas, along with partners like Nacelle Solutions, Avolta Development, and DVO, are working together with eco-conscious dairy farmers across Arizona to reduce greenhouse gas emissions and produce renewable natural gas for use in households, vehicles, and more.

Its latest project with Butterfield Dairy in Buckeye, Arizona, is working to capture the methane from dairy manure produced by more than 25,000 cows and convert it into over 300,000 MMBtu of renewable natural gas (RNG) annually. This is the equivalent of eliminating emissions from more than 3,600 cars — and it can power 2,925 households each year. As part of a sustainable and balanced energy future, RNG is one of the most promising new energy supplies — a sustainable low-carbon fuel produced by safely capturing, cleaning, and upgrading biogas produced from various sources, including animal waste, wastewater treatment facilities, and landfills. 

At Butterfield Dairy, an anaerobic digester from DVO is used to convert the manure — composed mainly of methane and carbon dioxide — into biogas. The mixture is then upgraded to pipeline-quality natural gas using equipment from Nacelle Solutions.

“Nacelle’s upgrading equipment utilizes a variety of technologies to safely remove hydrogen sulfide, carbon dioxide, and other contaminants from the biogas to create renewable natural gas that meets pipeline specifications for quality and safety,” said Kim Sachise, director of marketing for Nacelle Solutions.

Following the upgrading process, RNG can be delivered through existing natural gas pipelines and is compatible with existing natural gas appliances, industrial equipment, and compressed natural gas vehicles without any modifications. This means end-users do not need to change their natural gas equipment to use RNG. 

Southwest Gas partnered on the Butterfield Dairy project to build the interconnection that allows RNG from the farm to be piped directly into the Southwest Gas distribution system and available to the market, helping businesses, communities and the transportation industry meet their respective emissions reduction goals.

“We continually strive to exceed our customers’ expectations by safely delivering reliable and sustainable energy which helps to preserve our natural resources, contribute to energy diversity, and foster economic development and growth in our communities,” said Dr. Laura Nelson, Southwest Gas vice president of sustainability and public policy. “Innovative energy solutions, like RNG, help communities move towards their decarbonization goals.”

Butterfield Dairy is owned and operated by the de Jong family, whose history of farming can be traced back to Holland nearly four centuries ago. 

“The dairy industry has seen a lot of change since our family started in the 1620s,” says Butterfield Dairy owner Tommy de Jong. “These RNG developments will not only help us to continue to care for our animals but will provide clean energy for generations to come.”

The Butterfield Dairy RNG project was developed by Avolta Development, a renewable energy company focused on originating and developing RNG projects; and the project began delivering gas into a Southwest Gas pipeline in the first quarter of 2023. In addition to upgrading the biogas to RNG, Nacelle Solutions operates and maintains the entire project, including the digester and upgrading equipment, as well as manure management.  

To date, Southwest Gas has constructed interconnections with five RNG projects in Arizona and California to transport pipeline-quality RNG to the market, with an anticipated production of over 13-million therms of RNG.