Hawai’i Gas

Hawai’i’s First RNG Facility


The Honouliuli Wastewater RNG facility produces about 800,000 therms of energy per year, enough gas for 6,000 homes. Through DMT’s two-stage membrane separation technology, biogas from two anaerobic digesters is processed and upgraded to a purified RNG stream which is then injected into Hawai’i Gas’ O’ahu utility pipeline to provide thermal energy for homes and businesses.

The Honouliuli RNG Facility equipment, painted an eye-catching bright green, takes the gases that are a by-product of anaerobic digestion and turns them into clean-burning renewable natural gas (rng).

Project Details

Product: Carborex® MS
Year: 2018
Location: Honolulu, Hawaii / USA
Biogas Inlet: 350 SCFM
Biogas Source: Wastewater Treatment Plant (WWTP)
Application: Pipeline Injection

In December 2018, Hawai’i Gas became the first in the state to capture and upgrade biogas, using DMT’s membrane separation equipment, the Carborex®MS. In partnership with the City and County of Honolulu, biogas is collected, processed and injected into Hawai’i Gas’ O’ahu utility pipeline to provide thermal energy for homes and businesses. The first-of-its-kind renewable natural gas (RNG) facility is equivalent to eliminating the need for nearly 15,000 barrels of oil and reducing greenhouse gases by the amount produced by 400 cars annually.

“The ability to capture biogas from our sewage (and transform it into RNG) is the type of innovative project that will help us reach our renewable energy goals sooner rather than later.”

– Mayor Kirk Caldwell, City & County of Honolulu

The Honouliuli Wastewater RNG Facility produces about 800,000 therms of energy per year, enough gas for 5,555 homes. By selling the biogas to Hawai’i Gas, the City and County of Honolulu estimates they will generate approximately $1.6 million of revenue per year. This $5 million project harvests waste energy that was previously being flared off into the atmosphere.

Project Results

The biogas upgrading project made the cover of Green, a quarterly magazine dedicated to topics of sustainability in Hawai’i. Because natural disasters are common to the islands, this project is an important piece to the state’s energy security and resiliency measures.

DMT’s project was a critical piece to Hawai’i’s resiliency plan for surviving natural disasters as well as reducing the state’s greenhouse gas emissions. As the premier provider of gas solutions since 1904, Hawai’i Gas supplies gas energy to nearly every major market segment: residents, food service, military, hospitality, health care, education, government, agriculture and more. After the biogas is upgraded, the RNG is delivered safely and reliably through Hawai’i Gas’ 1,100-mile underground utility pipeline, meaning that when winds are high and the power goes out, gas users can still cook and access hot water for sanitation.

“Ensuring that all families have access to affordable, reliable and clean energy are important goals. Our RNG project is an important step toward achieving these goals, while at the same time, working towards meeting Hawai’i’s carbon neutrality goals for 2045.”

– Alicia Moy, President & CEO, Hawai‘i Gas

Additionally, their vision is to improve Hawai’i’s quality of life includes developing innovative, renewable energy projects to reduce the state’s greenhouse gas emissions and to promote energy efficiency.

“In a way, all of us are making some of that gas and now it’s being used to save our planet and make it a lot bluer and greener and sustainable.”

– Mayor Kirk Caldwell, City & County of Honolulu
Hawaii Gas DMT Award
DMT’s general manager, Robert Lems, (left) shaking hands with Hawai’i Gas’ director of renewable energy, Richard DeGarmo, (right).

Project Recognition

Operational since December 2018, the project was awarded the “Biogas Project of the Year” in 2019 by the American Biogas Council for the deployment of DMT’s advanced gas cleaning technology on municipal biogas to reduce the carbon footprint of the Honouliuli natural gas system.

“This project was selected because it’s at the leading edge of a wave that will sweep the nation as more and more gas utilities purchase renewable natural gas (RNG) made from biogas.”

– Patrick Serfass, Executive Director, American Biogas Council

Follow the journey of Hawaii’s first RNG facility with Hawai’i Gas and DMT:

This RNG facility uses the Carborex®MS.

For key biogas contaminants, DMT offers one or a combination of technologies. The technology selection is based on an analysis of your biogas composition, inlet gas flow, pollution load and RNG application. Based on your CAPEX, OPEX and/or TCO needs, we provide our customers with an innovative, economical solution.