Miami-Dade advances plan to test wastewater sludge as ship fuel

Florida’s largest producer of solid wastewater byproducts will have a hand in determining whether the malodorous material can power cruise and cargo ships.

Miami-Dade Commissioners unanimously approved a measure by Raquel Regalado to commit $1.5 million worth of county services toward testing the sludge-as-fuel concept, which the nonprofit Provident Resources Group (PRG) says has “promising conversion rates.”

AECOM Services Inc., a construction and engineering firm that developed the process with PRG and three other firms, will provide another $1.5 million worth of in-kind services to match the county’s contribution.

Miami-Dade’s portion is to come next January, only if PRG and its partners can land a $3 million grant from the U.S. Department of Energy for the tests, which would be held at the county’s Central District Wastewater Treatment Plant.

The original plan, which Commissioners advanced in committee with uniform approval Nov. 13, was for Miami-Dade to contribute $3 million to match the federal grant. Regalado swapped that proposal with one pledging county resources instead.

She further amended the item, at the request of fellow Commissioner Danielle Cohen Higgins, to provide that PRG and its partners must show the county a proof of concept for the technology by March. The group discussed that deadline with the county “on numerous occasions,” according to Roy Coley, Miami-Dade’s Chief Utilities and Regulatory Services Officer.

Every day, Miami-Dade produces about 700 wet tons of biosolids, which are nutrient-rich organic materials produced during the wastewater treatment process. Recent regulatory changes aimed at reducing nutrient migration to water bodies, which leads to mass fish kills, has led to an increase in disposal costs.

Miami-Dade spends about $26 million yearly on various contracts for biosolid disposal, a memo from County Attorney Geri Bonzon-Keenan said.

The county spends millions more on dealing with the smell. On Oct. 1, Miami-Dade Commissioners unanimously OK’d contracts with three companies for the “control (of) odor caused by organic sewage and processed wet and dry sludge” that will cost the county nearly $2.7 million over five years.

Biosolids today are mostly used to treat soil, but restrictions to limit the contamination of pharmaceuticals and so-called “forever chemicals” called PFAS in the ground and water sources have reduced that practice. Maine banned land application of biosolids in 2022.

PRG, AECOM and partners Genifuel Corp., Merrick & Co. and Pacific Northwest National Laboratories say they’ve developed a technology called hydrothermal liquefaction to turn biosolids into marine fuel. Studies they’ve done so far show a waste-to-energy conversion rate of between 37% and 59%, a project proposal from the group said. But they need larger-scale testing to know how commercially viable it can be.

“(High) costs and scaling challenges have made municipalities hesitant to adopt such new technologies,” the group wrote in a project description. “This project aims to demonstrate how waste-to-energy pathways like (hydrothermal liquefaction) can effectively … environmental and regulatory challenges, providing an innovative and economically viable solution for biosolid management that also supports transportation decarbonization.”

PRG and its partners say their end goal is to build the nation’s first large-scale hydrothermal liquefaction facility at one of Miami-Dade’s wastewater treatment plants. Once completed, they said, the facility would be able to process about 21.5% of the county’s total biosolid production into 1 million gallons per year of biocrude, a crude oil-like product that can be refined into something similar to “sustainable fuels like Sustainable Aviation Fuel (SAF), renewable diesel fuel and marine fuel.”

The group noted that it would be advantageous to locate the facility in Miami-Dade, which is home to PortMiami, the nation’s busiest seaport.

“This facility will also lay the foundation for potential future expansions to treat Miami-Dade County’s full biosolids,” the group added. “Upon successful demonstration, this scalable model will encourage widespread municipal adoption across the U.S.”

The project’s advancement Wednesday comes as Miami-Dade continues to mull where to locate a new trash incinerator to replace one in Doral that burned to the ground in February 2023.

Like PRG’s proposed facility, the incinerator converted county waste into energy. But Commissioner Juan Carlos Bermudez, the immediate past Mayor of Doral, urged his colleagues to consider the two issues as entirely unrelated.

“I just want to make sure,” he said, “that when we talk about (this that) we understand what’s an apple and what’s an orange.”