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The burning question
Original post made
on Jun 27, 2014
A short stroll from the marshy sanctuaries of the Palo Alto Baylands, inside a concrete tower off Embarcadero Road, lies an inferno that would make Dante gag.
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posted Friday, June 27, 2014, 12:00 AM
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Posted by Cedric de La Beaujardiere
a resident of Barron Park
on Jul 6, 2014 at 1:12 pm
Cedric de La Beaujardiere is a registered user.
Jenny, It doesn't really matter when all the Organic farms will take sewage-derived fertilizer, because unfortunately such a small percentage of crops are organic. If we ever evolve our society such that organic is the norm rather than the exception, perhaps by that time we will have also evolved to not send toxics and metals down the drain. At such a time, a truly sustainable practice is to recycle all our nutrients back into the soil, as sustainable agriculture has done for thousands of years before the industrial era messed things up.
Steve, in response to your questions:
1) I'm not sure why there is that discrepancy in the GHG figures, perhaps the basis for what is considered 0 GHG is different in the latest analysis, however I note that the delta between the options is still on the same order of magnitude. Even though I served on the 2009 Compost Task Force, I consider the more authoritative estimates for GHG emissions to be those derived in the subsequent Feasibility Study (Web Link) which was more rigorous and thoroughly vetted by city staff, consultants, and the community. In that study, you can look, for instance, at page 13, where 'alternative 3' (22,716 MT) is closest to the status quo, and 'case 1c' (14,207 MT) is closest to the the option of AD for food & sewage and compost for yard. (Even though in case 1c yard and residential food would have been digested, and will now instead be composted, It is probably pretty close to similar GHG numbers because IIRC there is about 2x more commercial food than residential food and it is higher energy value (more fats and grease), and the planned AD plant would be more efficient with a pre-pended Thermal Hydrolysis Process (THP) which breaks open the cell walls allowing the Anaerobic Bacteria to get in there and release more energy.) So the delta between the comparable Feasibility Study options is about -8,500MT, whereas the delta between the status quo and the planned process from the latest RFP's analysis is about -8,300MT, which is surprisingly close.
2) The reasons to reject the bids and re-bid were legal and financial. The original RFP was crafted with the idea that we would get bids for newer technologies like Gasification or Pyrolysis (which Jenny said she would like the city to consider). Since these are newer technologies, the city was concerned that they might still have kinks and tweaks to work out, and so crafted the RFP with the notion of private ownership and operation, such that the private party which bid on the design/build would also carry the risk if anything didn't work as planned. However, it turned out that none the 3 viable bidders (I don't recall, maybe also none of the initial 7 bidders) bid for these technologies. Instead the qualified options were shipping it all away (Synagro bid) or doing one of two forms of AD for food & sewage and composting yard.
Since AD is an established technology (and the predominant technology at least in California for sewage), the city staff felt they could get better pricing if this component were city owned and operated, and it would reduce confusion having one central authority managing all processes within the RWQCP (rather than having a private operator working a subset of the public RWQCP). While Harvest had a more holistic bid meeting the desires of the community (as judged by the passage of Measure E) for local processing of everything, Cambi/WeGeneration proposed a more energy efficient technology set for the AD components (Thermophylic Hydrolysis (THP) + AD). Harvest and WeGeneration were willing to combine their bids and negotiate for shorter timeframe for city ownership. However, it was felt that the city would open itself up to a legal challenge if they were to go this route, because other companies could say they would have bid for a project with city ownership, or they could say it is unfair to allow these two companies to change their bids to suit the city, after the closure of the bid period.
3) My recollection is that one of the two bid AD processes would produce a dried (using recaptured heat) pelletized fertilizer while the other was perhaps composted or just dewatered to produce a more loamy fertilizer. Page 88 of the staff report #4744 (Web Link) has a neat diagram for the THP+AD process which shows land application of the resultant solids. (My recollection is that in the city's Feasibility Study of 2011/2012, sales for sewage-derived compost was set at $0/ton, but I think the AD bidders anticipated non-zero but fairly negligible revenue for such sales). In the Synagro case as well, the sales of fertilizer partially (probably marginally) offset but do not fully cover processing costs. As such, municipalities delivering sludge pay a tipping fee (measured in $/ton delivered) to Synagro, which covers most of the cost to process.
It is important to note that whatever the city does, there will always be cost to handling municipal organics (sewage, food, and yard). Whether it is Landfilled, Incinerated, Gasified, Digested, and/or Composted, there is a significant cost. If we just did nothing, there is ongoing operational cost and significant risk of equipment failure with high cost to deal with such a failure (emergency trucking away of an endless poop stream). As such, it is a question of what will people actually bid to construct, and of those options, how do we optimize for least cost and least ecological impact. I think the city is on a good path for optimizing towards an environmentally and economically responsible solution.