Shipping the city’s food scraps, yard trimmings and solid organic waste to large, regional facilities may pump twice as much greenhouse gas into the atmosphere as a local aerobic digestion plant, and may not be any cheaper, according to a report presented to the Palo Alto City Council Monday.
The report, which detailed a contentious preliminary analysis of alternatives for dealing with Palo Alto’s organic waste, or “residuals,” compared monetary and environmental pros and cons but was picked apart by city staffers who told the City Council not to read too far into it.
“We wouldn’t recommend drawing conclusions tonight from it,” said Phil Bobel, environmental compliance manager for the city of Palo Alto.
Up for debate is whether to build a dry anaerobic digestion (DAD) facility on a nine-acre portion of the city landfill at Byxbee Park, or to truck the city’s residuals to a DAD plant in San Jose or to a compost facility in Gilroy.
Right now, the city incinerates wastewater solids—known as “biosolids”—and ships away food scraps and composting yard trimmings, totaling about 60,000 tons per year. The city’s combined organic waste is expected to hit 74,000 tons per year by 2034.
Bobel said that the assumptions used in the study’s models would have to be rethought before city staff suggests a plan.
“A number of runs at the model with different assumptions would be good to see before drawing conclusions and making recommendations,” he said.
Even the consultant evaluating the DAD plans, Jim Binder of Alternative Resources Inc., agreed it was too early to draw conclusions, noting that the contractors who were contacted as potential vendors for processing the city’s waste were the ones who determined the estimated costs of those contracts.
Councilwoman Gail Price took issue with this fact.
“What is the process by which we validate these numbers?” she asked. “Am I misunderstanding what I heard … that the numbers were reported by the companies?”
Binder, who seemed uncomfortable defending an analysis he repeatedly explained was incomplete, said, “These are the best numbers that the companies can put forward. These are not bids. Companies aren’t in a position to be able to come up with those numbers.”
Indeed, there does not yet exist a dry anaerobic digester in the United States, he said, and thus any estimated cost is likely to be optimistically low. The DAD plant in San Jose, being built by Greenwaste, is still in the permitting phase and would be the first in the nation.
“My guess is that those numbers aren’t firm numbers, so just keep that in mind,” he said.
Furthermore, city staff insisted that public comments received earlier in the year had yielded tremendous input that should also be reviewed before making any final recommendations.
“It was the volume of comments from a range of perspectives by the public that really made it difficult to put us in a position to beg for some action,” said City Manger Jim Keene.
As Palo Alto Patch reported last fall, the two competing sides in this debate are both self-described environmentalists. In one corner, conservationists are arguing that Byxbee Park, which is protected parkland, should remain as such once the city landfill is taken offline next year.
Former City Councilwoman Emily Renzel told the council Monday night not to “ruin Byxbee Park” with an industrial anaerobic digester when the city could take advantage of regional offerings.
“It makes no sense for every small city to make massive capital improvements rather than taking advantage of economies of scale regionally,” said Renzel, who prefers that the city upgrade the Water Quality Control Plant in order to process biosolids and continue exporting the rest of its organic waste
“Zillions of dollars might drop out of the sky to improve the [anaerobic digester] odds, but don’t count on it. Sooner or later, the costs will fall on ratepayers,” she said in a letter to the council.
In the other corner, climate activists argue that the city should be responsible for its own waste, and that to build a digester locally would allow the city to come much closer to its climate protection goals and, perhaps, even generate renewable energy.
Former Mayor Peter Drekmeier, who helped gather signatures for an initiative that would change the parkland designation of the Byxbee Park site so it could be built upon, touted what he said were significant environmental benefits to building a local digestion facility.
“One thing that people do agree on is that this project would be good for the environment, reducing greenhouse gases by 12,000 tons,” he said. “That’s the equivalent of what would be released by burning 1.2 million gallons of gasoline.”
Drekmeier went on to say that a local plant would help the city meet more than half of its goals for climate protection and save the city more than $2 million a year.
Nobody in the Council Chambers seemed wholly convinced about the economic viability of DAD technology.
Multiple council members wanted to know if a wet anaerobic digestion facility that could process all three kinds of waste might be feasible for the water control plant, and if gasification of methane produced by such a device might be used to produce renewable energy.
And then came a third option—plasma arc conversion—touted by Councilman Greg Schmid as one worthy of examination.
“The city of Salinas has been recommended a [plasma arc conversion] project that will achieve 98 percent recovery or reuse of all municipal solid waste,” said Schmid. “The technology has been endorsed by the EPA as the future.”
“I think that Councilmen Schimid is on target,” he said.
The council eventually decided to table any decision on the issue until city staff could come back with better analysis of the DAD options as well as details of what would be required for an examination of the other alternatives presented Monday night.
That meeting will occur in June.