BIOSOLIDS TO ENERGY – A COALITION APPROACH

“The energy potential contained in wast ewater and biosolids exceeds by te n times the energy used to treat it.” 1

Biosolids are the nutrient ri ch natural by-product of wastewater tr eatment. 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 heat ing the material to break down the solids and create gases that can be converted to ener gy. 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, flui dized bed reactor and arc plasma.

There is significant potential for wastewater sector developm ent to help achieve st ate and federal goals to meet electricity needs with renewabl e sources – such as Pr esident 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 anim al wastes and sewage as eligible activities).

In California, biosolids ar e categorized as biomass in the Californ ia Energy Commission Renewable Energy Program guidebook 2 and are eligible as a renewable energy resource in the Renewable Portfolio Standard 3 . “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. pr oduces 7.2 million metric tons of “dry solids” – biosolids with the water taken out of it – annually. Currently, plants incine rate 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 pot ential would cut back the amount of bios olids land-filled and land applied, and will facilitate energy recovery from biosolids wh ile improving the United States energy security.

Across the San Francisco Bay Area, agencies have impl emented 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 coalit ion 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 pr esently 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 la ndfill 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 wi thin the Bay Area wo uld have the added benefit

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

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

1,4 “Energy Opportunities in Wastew ater and Biosolids”, April 2009 , Water Environment Research Foundationof 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 te chnologies, the BAB2E projec t is requiring that the technology used have air cleaning systems that guarant ee compliance with stringent Bay Area air quality standards. Coalition members are approaching this project with the conc ept that ALL air r egulations will be met at all times. The project seeks to maximize ne t energy production and deploy state of art equipment. Over the last few years, the c oalition has studied potent ial technologies and pr ocesses 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 re gional capacity prior to initiating the preparation of an environmental document.
The coalition is also working with its lobbyists to develop state and federal part nerships. State and federal investment in early projects is critical to providing models that will lead to BAB2E as a mainstream alternative for biosolids management.