BIOSOLIDS TO ENERGY – A COALITION APPROACH 

“The energy potential contained in wastewater and biosolids exceeds by ten times the energy used to treat 

it.”1 

Biosolids are the nutrient rich natural by-product of wastewater treatment. They are produced by removing 

the organics from municipal sewage - the majority of which comes from homes. Biosolids contain latent 

energy that can be harnessed via capture and combustion of methane gas or via direct combustion. The 

process to convert biosolids to energy involves heating the material to break down the solids and create 

gases that can be converted to energy. Depending on the technology used, heat requirements range from 

700 degrees Fahrenheit to 10,000 degrees Fahrenheit. Typical technologies used include pyrolysis, 

gasification, thermo oxidation, fluidized bed reactor and arc plasma. 

There is significant potential for wastewater sector development to help achieve state and federal goals to 

meet electricity needs with renewable sources – such as President Obama’s plan of generating 25 percent 

of the nation’s energy from renewable sources by 2025. In recognition, there is movement to legislatively 

define biosolids as a renewable resource (The draft Senate Energy Bill was recently reported out with new 

biomass definitions. As drafted the bill includes animal wastes and sewage as eligible activities). 

In California, biosolids are categorized as biomass in the California Energy Commission Renewable Energy 

Program guidebook2 and are eligible as a renewable energy resource in the Renewable Portfolio 

Standard3. “The over 16,500 publicly owned wastewater treatment facilities in the U.S. produce over 64 

pounds of biosolids per person, every year. The U.S. produces 7.2 million metric tons of “dry solids” – 

biosolids with the water taken out of it – annually. Currently, plants incinerate or landfill 45 percent of the 

biosolids, and treat and land apply 49 percent.”4 Investments in approaches to maximize energy recovery 

from this great untapped potential would cut back the amount of biosolids land-filled and land applied, and 

will facilitate energy recovery from biosolids while improving the United States energy security. 

Across the San Francisco Bay Area, agencies have implemented programs to capture methane gas 

through anaerobic digestion. However, energy value still remains in the biosolids after digestion. Sixteen 

Bay Area agencies have formed a coalition to create a local sustainable solution to biosolids management 

by utilizing the remaining energy. Identified as the Bay Area Biosolids to Energy (BAB2E) project, most of 

the participating agencies presently utilize a combination of hauling biosolids for land application and/or 

alternative daily cover at landfills and would like to see these beneficial uses preserved. However, 

increasingly restrictive regulations and diminishing landfill capacity have been the impetus to seek a long 

term sustainable alternative. The agencies are collaborating on a project to diversify biosolids 

management options with the development of a regional facility that will use biosolids and other biofuels to 

generate renewable energy. Locating a regional facility within the Bay Area would have the added benefit 

                                                           

2 http://www.energy.ca.gov/2007publications/CEC‐300‐2007‐003/CEC‐300‐2007‐003‐ED2‐CMF.PDF 

3 http://www.energy.ca.gov/2007publications/CEC‐300‐2007‐006/CEC‐300‐2007‐006‐ED3‐CMF.PDF 

1,4 “Energy Opportunities in Wastewater and Biosolids”, April 2009, Water Environment Research Foundation 
of reducing vehicle miles, currently estimated to exceed one million miles, and the associated greenhouse 

gas emissions associated with hauling. 

While open to the use of any of the available technologies, the BAB2E project is requiring that the 

technology used have air cleaning systems that guarantee compliance with stringent Bay Area air quality 

standards. Coalition members are approaching this project with the concept that ALL air regulations will be 

met at all times. The project seeks to maximize net energy production and deploy state of art equipment. 

Over the last few years, the coalition has studied potential technologies and processes for biosolids 

treatment and reuse and is now preparing public outreach materials, technology and site screening criteria, 

and identifying potential sites that could serve in a regional capacity prior to initiating the preparation of an 

environmental document. 

The coalition is also working with its lobbyists to develop state and federal partnerships. State and federal 

investment in early projects is critical to providing models that will lead to BAB2E as a mainstream 

alternative for biosolids management.