The western region of the United States is facing the worse of the country’s climate change and water scarcity problems. As a result, states like California are scrambling to adopt strategies that can help them adapt to these stresses.
With dreary forecasts of a severe multi-year drought and groundwater supplies already being over-pumped, these states need to prepare for a challenging future now. Meaning they must manage natural and working lands more sustainably, primarily by conserving water and transitioning to renewable energy sources.
In response to this need and the findings of a study by University of California-Merced (UC Merced) researchers, California approved a project to cover two canals with solar panels. The “Project Nexus” pilot will serve as a case study or proof-of-concept to the study, which outlines the substantial benefits of covering canals with solar panels for renewable power generation and water preservation, delivery, and quality.
It is a $20 million collaborative project funded by the State of California involving the Turlock Irrigation District (TID), the Department of Water Resource, the UC Merced, and Solar AquaGrid LLC.
Solar AquaGrid’s founders formed the unique public/academic/private collaboration after recognizing the untapped opportunity of shading California canals to halt evaporation. It was the one who commissioned the UC Merced study through UC Water and the Sierra Nevada Research Institute to advance California’s Solar Over Canal initiative.
More About Project Nexus
Project Nexus is not a floating solar panel (“floatovoltaics”) project. Instead, it consists of solar panel canopies – trusses that span the canal from one side to the other – with the solar panels mounted. The solar panels do not touch the water. As a result, animals will still be able to access the water for hydration.
The UC Merced study found that mounting solar panels over open water provides several advantages, including boosting the cells’ efficiency and saving water by putting a lid on evaporation. In addition, the researchers say that a solar panel array over water could generate a 20% to 50% higher return on investment compared to installing the same panels on the ground.
Project Nexus will take place on a portion of TID’s existing canals. The two locations are one outside Turlock Lake in the Hickman area and the other just out of Ceres. One is 110 feet wide, and the other 25 feet wide, respectively.
Josh Weimer of the TID said:
“In that section [TID], that first location, there are two different ways that we’re going to be doing it, facing the panel’s different directions — the canals [Hickman and Ceres] run a few different ways. And so, we are really going to be able to try out different types of mounting techniques right there at one location. So, these two options allow us to try out different technology for spanning and mounting solar panels over canals.”
The pilot aims to research how water-plus-energy can meet the state’s needs for climate resiliency. In addition, the TID will monitor and fine-tune the operation, keeping an eye on key performance indicators like:
- Water evaporation.
- Improvements to canal maintenance (if the panels help minimize aquatic weed growth).
- Water quality.
- Renewable energy generation and storage.
- Detect any logistics issues involved with installation and operation.
Ultimately, the TID wants to see if the UC Merced study concepts prove accurate, and if so, it will likely scale up the project.
Project Nexus breaks ground this fall and wrap up in 2024. It will include energy storage to analyze if the pairing can support the local electricity grid when solar generation conditions are insufficient.
Water-Plus-Energy Can Help California Meet its Climate Goals
Covering the approximately 4,000 miles of California’s public water delivery system infrastructure (canals, including the major California Aqueduct) with solar panels could generate 13GW of clean energy annually.
Currently, 13GW is about one-sixth of the state’s installed capacity. 13GW is also about 50% of the new capacity needed to meet the state’s clean electricity goals: to reduce emissions by 40% by 2030, with 60% of its electricity coming from carbon-free sources by 2030 and 100% by 2045.
Gov. Gavin Newsom told the Modesto Bee:
“We need solar energy all over the state to achieve our goal of decarbonizing our economy.”
Hence, Project Nexus could be a template replicable statewide to help with energy and water goals.
Project Nexus Could Support Microgrid Development
Local energy generation lowers transmission losses and the cost of electricity bills. Combine that with battery storage, and you have a more efficient and resilient power system. In addition, it would mitigate power loss risk from extreme weather, wildfires, and human error.
Microgrids are ideal for rural areas and underserved communities, empowering and providing them with more affordable electricity.
Developer Long-Term Cost Savings
While it is true that building ground-mounted systems are cheaper than spanning canals with solar panels, the co-benefits of the latter make it a better investment in the long run. Co-benefits include:
- Water savings.
- Enhanced PV efficiency.
- Avoiding land costs.
- Reduced canal maintenance costs due to aquatic weed mitigation.
Add together the savings that these factors deliver, and solar-over-canals projects provide cheaper electricity over the lifetime of the installations.
Solar-Over-Canals Projects Save Valuable Land
The state will not have to convert valuable land or disrupt natural habitats into sprawling solar farms. Building solar arrays over all the canals could prevent over 80,000 acres of land from being used. In addition, it would preserve culturally important land and ecosystems.
Dr. Brandi L. McKuin, the lead author of the UC Merced study, said:
“Solar canals are an example of an energy-water nexus that offer multiple sustainability benefits. Using water canals for solar infrastructure conserves water while producing renewable electricity and avoids converting large tracts of land to solar development.”
You would not put solar panels on your lawn when you can use your roof, and this is a similar circumstance. The canals are already long-disturbed land.
Michael Kiparsky, director of UC Berkeley School of Law’s Wheeler Water Institute, told Wired:
“You’re taking something that’s already been altered by human activity and doubling up on the benefits it provides. That’s the profound piece.”
Solar Panels Covering Canals Could Save Billions of Gallons of Water from Evaporating
California is a drought-prone state, and the situation is only expected to worsen as climate change brings drier and hotter weather to the region. The past 10 to 30 years have already seen wells dry up, massive wildfires, and severe water restrictions.
Jordan Harris, Solar AquaGrid’s CEO, said:
“Research and common sense tell us that in an age of intensifying drought, it’s time to put a lid on evaporation. Our initial study revealed that mounting solar panels over open canals can result in significant water, energy, and cost savings compared to ground-mounted solar systems, including added efficiency resulting from an exponential shading/cooling effect. Now is the chance to put that learning to the test.”
Covering the canals with solar panels reduces evaporation by shading the water from the sun. If the state expands Project Nexus to include all of California’s network of canals, it will save approximately 63 billion gallons of water from disappearing into the atmosphere.
Mr. Weimer said:
“In today’s world and how we are operating our system, saving every possible drop of water for future beneficial use is something that we are really trying to focus on. And so, any potential water savings is a water benefit to our ratepayers and to our growers.”
It Could Help Reduce the Water Networks Demand on the Electricity Grid
California’s water network is the world’s largest, moving more water than any other system on the planet. It serves 5.7 million acres of farmland and 35 million people.
The canals snake down and across the entire state to service these businesses and citizens because 75% of the available water is in its northern third, but the southern two-thirds account for 80% of the demand. Therefore, the pumping required to move all that water makes the water system the state’s largest electricity consumer.
Environmental engineer Brandi McKuin of the UC Merced and the UC Santa Cruz, and lead author on the paper, said:
“By covering canals with solar panels, we can reduce evaporation and avoid disturbing natural and working lands, while providing renewable energy and other co-benefits.”
Therefore, the solar-paneled canals would produce renewable energy for consumers and run the water system itself.
The Solar Panels Could Reduce the Growth of Canal-Choking Plants
The solar panels could reduce the number of weeds that grow in the canals by blocking the sunlight, preventing them from growing, and clogging irrigation.
Aquatic weeds are a significant maintenance issue, and they take up valuable water. Furthermore, roots can damage pipes and drains and restrict flow, and the plants can accumulate sediment that blows into the canals.
Mr. Weimer said:
“Maintaining our canals and making sure that those weeds are not blocking any of our irrigation delivery is a very large job that our construction and maintenance team do on a yearly basis. And so, the potential that this reduces canal maintenance is something that we’re very interested in.”
Plus, statewide savings on maintenance costs – including herbicides and mechanical equipment for extraction – could be substantial. The numbers are about $40,000 per mile for 100-foot-wide canals or $69 million annually extrapolated statewide.
Solar-Over-Water Boosts Panel Efficiency
The water’s cooling effects on the solar panels would boost their efficiency. Oddly enough, the opposite is also true: solar panels’ performance falls as temperatures rise.
Additionally, the canal water could cool the panels by an additional 10 degrees Fahrenheit compared to over-land solar arrays since water heats up more slowly than land, boosting electricity production by up to 3%.
The Human Benefit: Cleaner Air
There are also social benefits in addition to the several economic benefits of installing solar panels over all of California’s canals – most notably, better health thanks to cleaner air.
Air quality is a severe problem in central California, which has some of the country’s dirtiest air. Most farmers currently use greenhouse-gas emitting diesel generators to pump their irrigation water. If solar panels could provide that energy instead, it could improve air quality and reduce planet-warming emissions.
The Renewable Energy Could Power Electric Vehicle Charging Stations
Along with the rest of the world, California is preparing for the widespread adoption of electric cars. Conveniently, The California Aqueduct runs alongside Interstate 5, a major highway servicing traffic between the southern and northern halves of the state.
As a result, many gas stations along the route will need to be converted into car-charging stations over the years to come. Solar-paneling the California Aqueduct could supply all these stations with the power they need to charge the vehicles moving people and goods up and down the state with clean electricity.
Potential for Worldwide Application
Project Nexus could serve as a model for any location with canals.
Mr. McKuin says:
“[It] could easily be applied to other locations. For example, in water-stressed regions of the world with open canals, it makes a lot of sense to consider this.”
In a 2018 study by the National Renewable Energy Laboratory, researchers calculated that covering all the artificial reservoirs in the United States with solar arrays could provide up to 10% of the country’s electricity demand. Acknowledging their findings, the team called for more widespread use of the technology to help fight climate change.
In conclusion, solar-panels-over-water projects – however and wherever they are executed – are an exemplary solution. Therefore, the concept deserves serious consideration worldwide.
