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Taylor Diederich drills holes for pipe supports as workers install methane and natural gas fueled engine generators in the new Combined Heat and Power building at the Laguna Wastewater Treatment Plant in Santa Rosa, on Tuesday, July 10, 2012. (BETH SCHLANKER/ The Press Democrat)
Energy-from-waste project at Santa Rosa treatment facility poised to slash power costs, reduce greenhouse gas emissions
By KEVIN McCALLUM
THE PRESS DEMOCRAT
Cleaning wastewater requires huge amounts of energy.
It has to be moved with pumps, blasted with pressurized air and zapped with ultraviolet lights.
Even after it’s cleaned, it has to be pumped to local farms and soccer fields or piped 40 miles to be injected into the Geysers steam fields.
All that makes the Llano Road wastewater treatment plant, operated by the City of Santa Rosa, one of the largest energy users in Sonoma County, absorbing between 3 and 7 megawatts of electricity daily.
But an $11.3 million upgrade now under way promises to slash the plant’s power costs, reduce its greenhouse gas emissions and set the stage for other energy efficiency projects in the pipeline.
“It would insane not to do this,” said Mike Prinz, supervising engineer in Santa Rosa’s Transportation and Public Works Department.
The plant, which opened in 1968, can treat up to 21 million gallons per day of sewage from the cities of Santa Rosa, Rohnert Park, Sebastopol and Cotati. About 60 percent of its power comes from PG&E, with the plant running up a $2 million annual power bill.
The remaining 40 percent is generated on site by three massive generators that burn a mixture of natural gas and methane captured from the breakdown of human waste in silo-shaped vessels called digesters.
The heat produced from those engines is used to warm the digesters to 98 degrees, further reducing energy costs, optimizing the breakdown of the waste and maximizing methane production.
It’s an energy loop called cogeneration that gets engineers like Prinz pretty excited about their job.
“I think it’s amazing that we can treat a waste stream and harvest energy out of it to improve the quality of water and generate electricity,” Prinz said.
But the current generators are getting old, new regulations are restricting the use of natural gas in such engines, and the building that houses them is hot, poorly ventilated and never designed for the purpose.
So the plant is midway through a major upgrade of its “combined heat and power” systems that has been in the planning stages since 2006.
A new building has been constructed, four new 40,000-pound generators have been installed, and workers are hooking up the pipes and other system components for testing in the next few months.
“We’ll be running by the end of the year, for sure,” said Terry Schimmel, mechanical superintendent at the plant.
The new Cummings engines are larger than those being replaced. Each is the size of a large SUV, has 16 valves operating at up to to 4,160 rpm, cranking out 1,500 horsepower and producing 1.1 megawatt. More importantly, they are 33 percent more efficient than the old ones.
That alone will reduce the city’s PG&E bill by about $575,000 a year immediately, Prinz said.
In addition, $100,000 annually will be saved because that extra muscle means the plant won’t have to rent two massive generators for three months every winter as backup generators.
The plant needs to be able to produce enough power to operate if the power from PG&E goes out. During the rainy months, the existing generators couldn’t handle the plant’s entire load, requiring the rental of the two backups.
The savings will lead to an expected payback period of 14 years on the project, which Prinz said is excellent given that the generators — technically advanced reciprocating engine systems — are expected to last 50 years.
Other improvements include the ability to capture more heat from the engines through a two-step process that heats water from the engines themselves and from their exhaust, which is discharged at 1,200 degrees.
Ratepayers, who have seen rates more than double in the past decade, are funding the upgrades. The cash was raised through a $49 million bond issue in 2008 that has also funded part of the new Utilities Field Operations building in Santa Rosa, water conservation and urban reuse projects, and storage improvements.
To get the most out of its new investment, the plant is exploring how to generate additional methane from its four digesters. The more methane that can be produced and harvested, the lower the plant’s PG&E bills and emissions. One idea is to add other kinds of waste — food scraps, animal manure or even pumice from the winemaking process — into the waste stream to increase the production of what is known as bio-gas.
It’s a complicated decision, taking into account factors such the energy used to gather the additional material and how it would affect the reuse of what is left behind, most of which is turned into compost, said David Guhin, deputy director of operations for the plant.
Ideally, when combined with other renewable energy projects, increased use of bio-gas will be a key piece of the plant’s long-term goal to get off the grid entirely and keep down costs for ratepayers.
“Zero net energy use. That’s the holy grail,” Guhin said.
(You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com.)
UPGRADE PROJECT
Project: Upgrades to power plant and heat-capture system at wastewater treatment plant.
Cost: $11.3 million
Reason: Aging generators, new regulations and increasing future use of bio-gas.
Power: Four 1,500-horsepower, piston-driven gas generators each producing 1.1 megawatts.
Energy efficiency: 33% increase.
Savings: Reduction in operating costs by $675,000 per year.
Includes: New building, improved heat-capture system, gas-cleaning system, testing.
Contractor: Overaa Construction, Richmond
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GAJ, great point, We have the cleanest greenest electricity from the Geysers yet it does not count. I think we get like 80% of our electricity from there. Santa Rosa and sewer ratepayers have already paid for a HUNDREDS of MILLIONS pipeline to ‘recharge’ the Geysers Complex, and that doesn’t even count ! We have the Cadillac of sewer costs and facilities, brought to you by lawsuits.
So our ICLEI-mandated reductions have to come from somewhere. So natural gas is a main target, even though a fairly minor and clean-burning source.
To bear, let me know when Lake Shasta silts up. Or the Hetch-Hetchy system. Maybe 100 years from now ? And by then we will pump out the silt. It’s called ‘ American Ingenuity ‘ . The sky is not falling.
Spare me.
Natural gas from landfills is good. Natural gas as a by-product of conventional oil wells is good. Hydro power from large, established dams is good until they silt up.
Natural gas from “fracking” that appears to poison groundwater is not good. Hydro power from minor dams that screw up fisheries may not be worth it.
Fish or no fish?
Being spoonfed information from energy company sources is not good.
Oil spills like the one that poisoned the Kalamazoo River in Michigan are not good.
Did you know that oil from tar sands doesn’t float, and therefore can’t be recovered? It sinks to the bottom and poisons the water forever. But a pipeline running tar sands oil from Canada to Texas, for export to China, is good? Even if it runs through the aquifer that supplies five states?
Let’s get clear on the facts and the big picture, and make this a sensible discussion.
BTW the BOS was probably counting on staff they laid off to deal with the landfill issue. You folks expect a lot from skilled employees who are no longer there.
Remember, GeoThermal and Hydro Energy are also lumped in with Nat Gas, Coal and Nuclear as “evil” and cannot be used as a measure of municipalities’ achievement of “greener” or “cleaner” energy.
Steveguy:
the monopolization/colution between ICLEI and PG&E is significant.
PG&E is literally a ‘stakeholder’, a ‘public-private’ partner in the municipal crime that is ICLEI.
They were at the table in ’92 for the Rio Earth Summit where Agenda 21 was finally pitched.
We’re not supposed to know it yet, but PG&E will discontinue maintanance of their gas infrastructure.
I’m sure it will come out soon, all under the guise of our safety.
This represents another loss of choice, their goal being to have everyone in the ‘Smart Grid’ with mandatory over priced, low quality appliances with RDF chips that interface with the ‘Smart Meters’. This will facilitate complete monitoring and individual control.
Eventually ‘granting’ and rationing your power allotment as reconciled by the state.
That’s just the beginning of what the Smart Grid really represents.
As was discussed in the ‘Climate Action Plan’ story, our ICLEI adherant local government will circumvent the benefits to clean burning, plentiful, economical natural gas pursuant to ICLEI directive.
Although not knowledgeable about the mechanics of the plant, on it’s face value, it seems like a good move, in and of itself.
“Giving the people cheap energy, is like giving a machine gun to a child”
-Henry Kissinger, globalist
Did you catch that? They’re building new natural gas power plants to run the thing. I thought we weren’t supposed to be using natural gas! It’s OK for them to use it but not us. They want everybody to use electricity only so they can monitor every bit of energy we use. Smart meters/Smart grid allows the government to monitor and control how much and when we are allowed to use electricity. It’s harder to do that with gas appliances. It’s not about what’s good for people it’s about control.
A guest on C-Span’s Washington Journal gave a good example of that control when he said we might try to turn on a clothes dryer but it wouldn’t work until the middle of the night. Santa Rosa City councilmember Susan Gorin said we were entering into a “Brave New World” at a recent City Council meeting when discussing the city’s Climate Action Plan. Unfortunately, she’s right and she’s helping. Don’t vote for her for Sonoma County Supervisor.
The plan to use electricity to replace ALL natural gas use is not only misguided, it is insane.
Natural gas is cheap plentiful ( with modern methods, it is estimated that we have hundreds of years of natural gas reserves.
Gas stoves, water heaters, furnaces and clothes dryers are FAR more efficient than electric appliances and are FAR cheaper to run. . Santa Rosa’s climate action plan actually says that they want to dis-allow natural gas use.
We should be converting MORE of our energy use to compressed natural gas ( CNG ) as a very clean burning ‘ bridge fuel’ Especially in the trucking industry.
Not utilizing a ‘better evil’ is not only misguided, to me it is criminal. If we put 1/10th the money into CNG conversions that we do for solar- especially Solydra type rip-offs- the payoffs in cleaner air would be tremendous. Besides it is cheaper, the ‘equivalent’ of around $2.50 a gallon ! Truckers now pay around $5 a gallon for diesel.
Our planners seem to have a myopic lock-step attitude that doesn’t allow for common sense.
This an amazing, cutting-edge facility. Generating energy off waste while disposing of it is exactly what we need to stop using fossil fuels. Human waste is infinite, oil is not. Pretty simple actually. But…I’m sure the Agenda 21 crowd thinks this is some Fascist/Marxist/Obama conspiracy to take their private property and guns.
A worthy project with a decent payback.
The little tidbit everyone should be aware of is buried in the story:
“new regulations are restricting the use of natural gas…”
The State believes Natural Gas, (a plentiful resource in the US and relatively clean compared to coal and diesel) is evil and will pressuring homeowners in the coming years to eliminate it in favor of electricity.
Never mind that it will increase costs for the homeowners with questionable “improvements” for the environment.
Nevertheless, this project sounds like taxpayer money well spent.
Bravo.