Toilet flushing in Manteca generates a $1.1 million-plus annual PG&E electrical bill.
That covers the cost of running equipment at the wastewater treatment facility that separates waste from water and purifies the water to the point it is cleaner than river water when it is returned to the San Joaquin River.
Manteca leaders want a smaller power bill.
And they figure that since PG&E rates never drop the only way to reduce power costs is for the city to generate its own electricity.
The five-year capital improvement plan that’s part of the proposed Manteca municipal budget for the fiscal year starting July 1 includes spending $3.8 million to wean the wastewater treatment plant off the PG&E power grid.
It would involve deploying a photo-voltaic solar system and/or co-generation systems powered by methane gas. Initial studies indicate there is a possibility the city has the ability to generate all of the electricity they need for the treatment plant at significantly lower cost than PG&E charges.
The city has already issued a $135,000 contract to determine the feasibility of such an undertaking. Staff is proposing spending $1.6 million in the 2014-15 fiscal year, $160,000 in the 2015-16 fiscal year, and $2 million in the 2016-17 fiscal year to put in place systems for generating electricity.
The city has acreage around the treatment plant for a possible solar farm but staff has noted the land could be put to more valuable use. The city is working on a long-range proposal to convert much of the land into a business park as well as a family entertainment zone.
Instead solar panels doing double duty as shade structures for parking could end up covering all 500 plus spaces the city owns at the adjacent Big League Dreams sports complex. The shade/solar panel structures would be much like the ones at the new transit complex at Moffat Boulevard and South Main Street.
Staff has indicated if additional panels are needed, they may approach the owners of the Stadium Retail Center with the concept for use on parking lots in front of Costco and other retailers. They are waiting to see what figures the consultant comes up with in their study.
Not only would a solar system reduce current power costs but it would provide a hedge of sorts against future electrical rate hikes.
The consultant is also exploring how the city could use carbon tax credits to their advantage through how the project is financed in the private sector.
The lifespan of such a system is at least 15 years. The cost recovery of the investment expected to take six to seven years. That means if power prices do not change and use remains constant (both are anticipated to increase, though), the city could save up to $9 million in 15 years after recouping its original investment based on preliminary estimates provided when the council was asked to hire a consultant for more detailed work.
The city is also exploring the economics of a co-generation plant where methane gas — a byproduct of the retreatment process — is used to turn power turbines. Methane is generated around the clock. Solar power is only generated during daylight hours. Currently the methane gas is burned off into the atmosphere.
Funding for the solar project would be taken from fees collected monthly on residential and business sewer charges. The goal is to try and eliminate and/or minimize future rate increases because of rising power costs. Savings could also help offset increases in other parts of the plant’s operations such as chemical purchases.
Staff has noted if South San Joaquin Irrigation District were to become the retail electricity provider for the city, it would take a bit longer to retrieve the cost savings due to the SSJID goal of delivering power at costs 15 percent below PG&E prices.
The SSJID has indicated they might even be willing to consider participating in the creating of a solar farm at the treatment plant.
A solar farm needed to help power the treatment plant has been estimated to cover up to 20 acres. That would be about 40 percent the area of Woodard Park.