Renewable Natural Gas at the Honouliuli WWTP

“Ensuring that all families have access to affordable, reliable and clean energy are important goals”

Hawai’i Gas became the first in its state to capture and upgrade biogas, using DMT Clear Gas Solutions’ membrane separation equipment, the Carborex®MS. In partnership with the City and County of Honolulu, the first-of-its-kind renewable natural gas (RNG) facility is equivalent to eliminating the need for 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,” said Mayor Kirk Caldwell, City & County of Honolulu.

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 of up to 97%. The pipeline-spec RNG is then injected into Hawai’i Gas’ O’ahu utility pipeline to provide thermal energy for homes and businesses.

“This project started back in August 2015 when the City and County of Honolulu came out with a Request for Proposal (RFP) to sell their biogas. In September 2016, we were awarded the project and by December 2018, it was up and running,” recalled Richard DeGarmo, Director of Renewable Energy and Capital Projects, Hawai’i Gas.

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. Hawai’i Gas selected the biogas upgrading equipment based on DMT’s experience, 24/7 customer support, and technology performance. Currently, membrane separation technology dominates the US RNG market due to its low carbon footprint, low operational costs and operational ease.

“The highest priority for a biogas upgrading system is uptime.” said Robert Lems, General Manager, DMT Clear Gas Solutions. “Membrane separation technology yields high methane recovery and offers better system performance overall. We designed a system that’s easy to operate, easy to maintain and has over 98% uptime, which is unique to the industry.”

Hawai‘i Gas supplies gas energy to nearly every major market segment in its state: residents, food service, military, hospitality, health care, education, government, agriculture and more. As the premier provider of gas energy since 1904, their vision is to improve Hawai’i’s energy landscape by developing innovative, renewable energy projects to reduce the state’s greenhouse gas emissions and to promote energy efficiency. Additionally, this project is a critical piece to Hawai’i’s resiliency plan for surviving natural disasters. 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 vision for carbon neutrality by 2045,” stated Alicia Moy, President & CEO, Hawai‘i Gas.

During the American Biogas Council’s 19^th annual Biocycle REFOR19, the project won the 2019 “Biogas Project of the Year” award 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,” said Patrick Serfass, Executive Director, American Biogas Council. “This project, and others like it, promote the recycling of organic material that would otherwise be considered waste into renewable energy. They help to protect our environment, reduce our use of fossil fuels and also create new jobs.”

Since Hawai’i has no naturally occurring source of natural gas like those found on the mainland, this RNG project diversifies the state’s local energy supply using existing gas pipeline infrastructure, enhances their energy security and provides an additional revenue-stream. Because the first-of-its-kind RNG facility proved to be such a success, both the state and Hawai’i Gas are looking to the future and focused on further developing more biogas upgrading projects.

“It has been a privilege working with Hawai’i Gas on this groundbreaking project. They have proven to be a vital gas company for its community and state, and DMT looks forward to working with them again in the future,” stated Lems.

About Hawai’i Gas

Hawai’i Gas is the state’s only government-franchised, full-service gas company manufacturing and distributing gas. The company’s market includes Hawai’i’s approximately 1.4 million residents and nearly 8 million visitors. Hawai’i Gas manufactures synthetic natural gas, or SNG, for its utility customers on O‘ahu, and distributes liquefied petroleum gas, or LPG (propane), to utility, tank and bottled gas customers throughout the state’s six primary islands. It also produces renewable natural gas at Honouliuli Wastewater Treatment Plant on O’ahu. Hawai’i Gas is a wholly owned indirect subsidiary of Macquarie Infrastructure Company.

Case Study Location: Honolulu, Hawaii, US
Flow: 350 SCFM
Biogas Feedstock: Honouliuli Wastewater RNG facility
Application: Pipeline Injection
Partners: DMT Clear Gas Solutions and Hawaii Gas