California has around 4,000 miles of canals that shuttle clean water throughout the state. New research shows that these canals can do way more than bringing California’s residents with drinking water—paired with solar panels, these canals might also be a way to both generate solar power and save water.
This new study presents an analysis from researchers at the University of California Merced and University of California Santa Cruz that quantifies the economic feasibility of building a “solar canal” system in the state.
California’s water system is one of the largest in the world and brings critical water resources to over 27 million people. Brandi McKuin, a postdoctoral researcher at UC Santa Cruz and lead author of the study, found that that shading the canals would lead to a reduction in evaporation of water, kind of like keeping your glass of water under the shade instead of out in the open on a hot summer day prevents evaporation from stealing sips. Putting up a solar panel using trusses or suspension cables to act as a canal’s umbrella is what makes the double-whammy of a solar canal.
“We could save upwards of 63 billion gallons of water annually,” she says. “That would be comparable to the amount needed to irrigate 50,000 acres of farmland, or meet the residential water needs of over 2 million people.” Water is of especially critical importance to California, a state regularly stricken with drought.
Beyond just cooling down canals, those solar panels can pick up loads of energy from being out in the open sunlight. While the analysis didn’t measure how much capacity these solar panels would have, McKuin estimates through a “back of the envelope” calculation it would be about 13 gigawatts, or “half the projected new capacity needed by 2030 to meet the state’s decarbonization goals.” With that kind of electricity, there is a possibility that diesel powered irrigation pumps, which do a number on air quality, could be replaced.
Kiparsky finds the idea of tying electricity generation with the water system that uses a vast amount of electricity intriguing. “I like the idea of making things internally renewable,” he says.
Aquatic weeds also plague canals and can bring water flow to a standstill, but the researchers found that by adding shade, and decreasing the plant’s sunshine slashes the amount of weed growth. McKuin says preventing weed growth would also lighten the load for sometimes costly mechanical and chemical waterway maintenance.
Placing solar panels above existing canals can also spare untouched natural land that is frequently slated for sometimes expensive or environmentally destructive solar panel installations. “I think one of the important parts of this story is that in California we have this mandate to produce renewable energy at scale, but we also have to be careful about taking large parcels of land,”
