Some water suppliers are already incorporating clean energy into their portfolios. At the top of the list is the Sonoma County Water Agency, which, as of last year, is getting 100 percent of its electricity from carbon-free sources.
They achieved it through power contracting and building a few of their own projects, said Cordel Stillman, the deputy chief engineer of the agency. “We still have emissions from our treatment plants and our vehicle fleets, but as far as electricity is concerned, we have zero greenhouse gas emissions,” said Stillman.
They didn’t achieve the feat on their own. “We belong to a Joint Powers Authority – it’s a group of 13 water agencies and irrigation districts in the state,” he said. “We joined together to pool water resources and power resources so this gives us the ability to contract the power sources that we want – we don’t have to take what PG&E (Pacific Gas and Electric Company) or someone else gives us.”
The agency may get to achieve another first in California next year – the country’s largest floating solar project. Flat land in Sonoma County has a high value for growing premium grapes and the rolling hills are valued for their aesthetics, so the water agency decided to greenlight a project to put solar panels on floating docks on four holding ponds used to store recycled water. The ponds are bermed (surrounded by mounds of earth) so the panels are not visible from a distance and the panels help prevent evaporation on the ponds.
Stillman said the project is likely to be running by next year and supplying 9MW of electricity, most of which is contracted to go to Sonoma Clean Power, the local electricity provider.
San Diego County Water Authority (SDCWA), which has 24 member agencies, may soon follow suit. It is looking at doing 6MW of floating solar on one of its reservoirs. But the agency is already employing other sources of renewable energy.
“There is a water-energy nexus,” said Kelly Rodgers, the energy program manager for SDCWA. “We actually formed an energy program about a year ago, just because we realized that a large part of treating and delivering water is the cost of the energy.”
SDCWA has solar panels on three of its facilities – two office buildings and a water treatment plant. The panels are part of a power purchase agreement with Borrego Solar, which means that the water agency had no upfront costs and there’s no equipment to maintain. “Over 20 years, we are saving about $5.6 million,” said Rodgers. “It was a no-cost capital investment for us.”
The agency also employs in-line hydro at the Rancho Penasquitos Pressure Control and Hydroelectric Facility, which is able to produce 2.5MW by harnessing the energy in a pressurized water pipeline that is part of the water delivery network.
“Basically it is pure green energy,” said Rodgers. “It just takes excess pressure and spins turbines.”
This clean energy is estimated to reduce emissions of sulfur and nitrous oxide each year by 200 tons and reduce 60,000 metric tons of carbon dioxide a year. SDCWA also sells power to San Diego Gas and Electric – enough clean energy for roughly 5,000 homes, which also earns SDCWA $1 million in revenue annually.
The water agency is evaluating three additional sites for in-line hydro and it has plans to install batteries at several facilities that will store power to use when the grid is at peak demand, saving about $100,000 a year.
Other water suppliers throughout the state have also bumped up their use of clean energy in other ways. East Bay Municipal Utility District utilizes its waste stream – capturing the biogas as microorganisms break down food scraps, and waste from sewage, wineries and poultry farms. The energy captured helps to power the wastewater treatment plant and excess energy is sold back to the grid.
The Inland Empire Utilities Agency also generates 2.8MW of electricity from biogas fuel cells, as well as 3.5MW from solar and 1MW from wind – accounting for more than half the peak energy demand of the agency. But the ultimate goal is much higher.
By 2020 the agency is “trying to achieve peak power independence – being independent from the grid during peak periods, so during the middle of the day in the summer we can generate enough renewables that we could ease the demand on the grid,” said Jesse Pompa, a senior engineer at the agency.
To help with that, the agency is employing batteries. “What the batteries allow us to do is to optimize the power generated from the renewables,” said Pompa. “We have time-of-use pricing from Southern California Edison, so we can charge the batteries when it’s most economical and we can discharge and use the power to avoid the higher cost of power at different times of the day.”
Speed Bumps Ahead
Some water suppliers are on board with using renewables – seeing the environmental and economic value. But, besides a few standouts, is there more widespread adoption across the sector?
It’s impossible to know.
Right now electric utilities are required to disclose the source of their electricity mix – how much is coal, natural gas, solar, hydro, etc. But there is no such requirement for the electricity used by water or wastewater utilities.
That could change, though. California Senate Bill 1425, introduced by Sen. Fran Pavley, would create a registry to collect data on greenhouse gas emissions from energy use by the water sector. The bill has passed the Senate and moved to the Assembly.
“It starts voluntary reporting on the energy intensity and greenhouse gas emissions for water suppliers at a utility scale,” said Christian-Smith. “If we want to make informed decisions and find areas that meet our climate and water efficiency goals, we need this kind of information.”
Without this data, “it is much more difficult for water utilities themselves to identify clean energy opportunities that may help them save money and protect their ratepayers from uncertainty due to climate change or fossil fuel price volatility,” wrote Christian-Smith and Laura Wisland in a report last year from the Union of Concerned Scientists.
Right now the only information that’s available on the breakdown of energy use in the water sector are the handful of water utilities that are also electricity providers. And among those, Christian-Smith said, the amount of clean energy used varies greatly.
There are other reasons it can be hard for water suppliers to add more clean energy. “It’s not really articled as being within the purview of their work,” said Christian-Smith. “So it requires getting new info, new skills, entering into power purchase agreements or partnerships with electricity providers – that can be difficult.”
There are also physical hurdles. Wastewater treatment plants can produce biogas, but getting interconnections to sell it back to gas companies can be tough.
And, she said, the water sector lacks a clear roadmap of the path to clean energy – while the sector itself is fragmented. California’s energy market is dominated by a handful of large investor-owned utility companies. But for water there are thousands of providers in the state and many are publicly owned. “It’s a really different institutional structure,” she said. “It can be difficult to create a program and have it apply broadly.”
Publicly owned utilities often don’t carry large profits from year to year and may not have the cash on hand to meet upfront costs, she said.
“The economics are always very difficult,” said Pompa. “As a public agency our goal is not just to throw as many renewables at the wall, but to do it in a cost-effective manner.” What Inland Empire Utilities Agency and others have found most effective are power purchase agreements with energy companies that don’t require any capital outlay. “That’s what allowed us to get all the renewables in at a competitive price – solar, wind and fuel cells,” he said.
If done right, moving to renewables could be an economic boon for water suppliers, in addition to helping the state meet its climate goals. “Renewables lock in a stable energy cost,” said Christian-Smith, which is important because water utilities can’t easily or quickly change water rates if there are fluctuations in the fossil fuel energy market.
And it can even help generate income. “Participating in the clean energy transition can open up new revenue sources for the water sector, including the sale of excess renewable electricity or receipt of renewable energy credits, cap-and-trade proceeds, payments for providing grid services and fees for accepting organic wastes for renewable energy generation,” said the Union of Concerned Scientists’ report. “The water sector is poised to become a greater part of the energy and climate solution.”