Preliminary audit predicts revenue for AWA digester
Processing food waste could generate $2 million in savings
The company that recently began a preliminary energy savings audit of the Altoona Water Authority’s Easterly Sewer Treatment Plant has found the authority should be able to obtain enough high strength food waste to warrant construction of an anaerobic digester.
Energy System Group of Linthicum Heights, Md., estimates that a digester could generate $2 million per year in savings or additional revenue at a cost of $1.75 million — including debt service — for net annual earnings of $250,000.
The revenues and costs are based on a conservative inflow of 40,000 gallons a day of food industry waste, but there would probably be 90,000 gallons available if the authority sought it aggressively — with a proportionally bigger earnings potential, according to ESG Senior Business Development Manager Larry Doyle, who spoke to the authority last week.
ESG expects to finish its preliminary audit in late February, after which the authority would need to decide whether to order a 10-month investment grade audit, at which point it would be committed to either pay for that more detailed audit or ultimately proceed with a digester project — the cost of which would include the price of the second audit.
Typically, an investment grade audit costs about $500,000, or 4 percent of the cost of the digester project, Doyle said.
The project would call for creation of an anaerobic system to receive trucked-in “High-Strength Waste” (HSW) slurry from food processing plants, including poultry and rendering operations; dairies, restaurants, schools and companies that dispose of expired products, all located within 50 miles, according to Doyle and ESG Manager of Organics Acquisition and Operations Aidan Murphy.
The authority would receive payment for taking the food waste, while the anaerobic digestion of that waste would produce biogas, which could be burned on site to heat buildings at the treatment plant or to dry out sludge produced by the plant and the digester, or sold to the gas company or burned on site to generate electricity that could be used to operate the plant or sold to the grid, according to Doyle and Murphy.
The liquid effluent from the digester’s processing of the slurry, which would be about 8 percent solids, would go into the regular aerobic system at the plant, along with the regular sewage inflow, which is only about 0.01 percent solids, according to Todd Musser, director of wastewater treatment operations for the authority.
Drying out the sludge would produce a Class A product, which, unlike the Class B product currently produced at the plant, is pathogen-free and could be used for mulching homes and in gardens, according to Musser.
The authority has used the excess capacity of the plant during the past year to generate about $2 million in additional revenue from processing leachate, including brine runoff from tarps and muddy water used for predrilling pipelines under rivers.
But the availability of leachate isn’t consistent, so the revenue from that isn’t reliable, Murphy said.
The need for processing food waste, however, is consistent and growing, because environmental oversight agencies that have allowed it to be spread on land are tightening, due to concerns about environmental damage to rivers and lakes, according to Murphy.
“It’s coming to an end,” Murphy said.
That prospect makes producers of that waste receptive to reliable depositories like the authority would be, because they know that municipal treatment plants aren’t “going away,” Musser said.
The authority would probably sign multi-year contracts with those producers, Murphy said.
Operating a digester probably wouldn’t require additional authority employees, according to ESG.
If the authority agrees to a project, ESG would serve as the general contractor and be paid accordingly, according to Doyle.
ESG would plan the project to function for 20 years and would need to guarantee that the authority would at least break even during that time, based on the energy-savings program administered by the Pennsylvania Sustainable Energy Fund and the state Treasury Department under which the project would be financed and administered.
The financing deals must be for no longer than 12 years, an authority consultant said previously.
ESG would assist the authority for a consulting fee during the years of digester ramp-up, as the operation would be “a little complicated,” Murphy and Doyle said.
Generating additional revenue based on the excess capacity of the plant with leachate and potentially with the digester project helps keeps rates lower than they would be otherwise for authority customers, Musser said.
“If we can get people from outside paying the bills, it helps the citizens of Altoona,” Musser said. “We can make this the utility of the future.”
Mirror Staff Writer William Kibler is at 949-7038.