Arizona could substantially expand renewable natural gas (RNG) production from organic waste streams, with landfills and large dairy operations representing the state’s strongest near-term opportunities, according to a new assessment from the Center for an Arizona Carbon-Neutral Economy, Energy Vision and Southwest Gas Corporation.
The report evaluates RNG potential from landfill gas, animal manure, wastewater treatment plants and food waste, along with less commercially mature pathways involving woody biomass and other feedstocks. Drawing on modeling from the American Gas Foundation, the authors estimate Arizona could produce 23 million MMBtu of RNG annually under a low-development scenario and 43.6 million MMBtu under a high-development scenario. The theoretical technical potential reaches 143.7 million MMBtu annually.
Landfills dominate the nearer-term estimates. Landfill gas represents approximately 59% of Arizona’s total RNG potential in the low scenario and 54% in the high scenario. The report identified 18 of Arizona’s 40 municipal solid waste landfills as candidates for landfill gas energy projects. Seventeen landfills currently collect and flare gas without an operational, planned or under-construction energy recovery project. Four facilities — City of Glendale Municipal Landfill, State Route 85 Landfill, Butterfield Station Landfill and Los Reales Landfill — were identified as particularly strong near-term RNG prospects.
Animal manure represents another significant opportunity because Arizona’s dairy industry is unusually concentrated. About 92% of the state’s approximately 200,000 dairy cows are located on just 29 farms with at least 2,500 cows. The report estimates manure could provide 2.2 million MMBtu of RNG annually under the low scenario, increasing to 22.5 million MMBtu at the technical maximum. Building AD and RNG infrastructure across Arizona’s dairy and swine sectors, however, could require an estimated $1.2 billion to $1.3 billion in upfront capital.
Food waste and wastewater represent smaller opportunities. Arizona currently lacks a statewide food waste diversion mandate and widespread collection infrastructure, limiting the amount of material available for anaerobic digestion. Existing projects include the Stanfield RNG Facility, which co-digests more than 50,000 gallons per day of food waste along with predominantly dairy manure, and the City of Mesa’s Food-to-Energy pilot.
Overall, the report’s authors conclude that Arizona’s most immediate RNG opportunity lies in capturing methane from large landfills and concentrated dairy operations, particularly where projects can connect economically to existing natural gas infrastructure and transportation fuel markets.
