Ag Pumps Study Details Surprising Energy Savings

A new study by Cadeo finds that upgrading the nation’s crop land irrigation system could save $2.8 billion.

When most people think of agriculture, they do not think of pumps. Yet upgrading the nation’s irrigation system’s 600,000 pumps to more energy efficient models and using underground pipes could slash energy use in half. It can also eliminate 10 million metric tons of carbon emissions, replace the equivalent of four utility-sized coal power plants, and save farmers $2.8 billion. The pump upgrades alone could save $1.8 billion.

Those are the headline findings from a new study that Cadeo Group presented at the Hydraulic Institute’s Technical Meeting in October. Cadeo is a clean energy consulting firm that works with utilities to develop programs to bolster energy efficiency.

The numbers sound impressive, but they come with a caveat, said Peter Kernan, a Cadeo senior associate who focuses on emerging technologies. The study, he explained, focused on technical potential—the potential to replace one technology with another—without getting too deep into the economics. Think of it as a best-case scenario for energy efficiency.

Still, 600,000 pumps are a lot of pump systems—and there are good reasons to believe many of those systems will need upgrading soon.

Irrigation

For the past 20 years, farmers have faced a more challenging and extreme climate, especially in the western United States. The West has suffered a two-decades-long drought that has dried up rivers and dropped the enormous Lake Mead reservoir on the Colorado River to its lowest level ever.

This has had an impact on farmers. Farmers irrigate more than 40 percent of U.S. crop land, much of that in the ordinarily dry West, using a network of open-air canals that stretch more than 200,000 miles. Many are essentially unlined ditches. According to Idaho National Lab, roughly 30 percent of all water used for irrigation is lost to evaporation and seepage into the ground. Even concrete-lined canals, like those found in California, lose a great deal of water to evaporation.

“Water has always been important in the West, and many water systems, which are owned by farmers, are modernizing,” Kernan said. “Some are doing it to cope with reduced allocations of water, while others are trying to get ahead of regulations. They are converting those unlined, open-air irrigation canals to buried plastic piping to bring water to farms.”

That conversion could involve many of the nation’s 600,000 irrigation pumps. According to the U.S. Department of Agriculture’s Irrigation Water Management Survey, 76 percent of those pumps lift groundwater from wells, 17 percent pull surface water from lakes and river, and 7 percent boost water within irrigation systems or move discharges from fields.

New Pumps

Installing new, more efficient pumps, switching to variable frequency drives (VFDs), and electrifying pumps that run on fossil fuels could save farmers $1.8 billion alone, Kernan said.

The gap between average efficiency and maximum efficiency across pumps in the Department of Energy’s database shows a 13 percent difference in efficiency. Even at low ag pump duty cycles (about 70 percent of municipal pumps), the extra efficiency could save about $1,000 per pump per year, or $587 million, Kernan said.

Outfitting all pumps to use variable frequency drives could save farmers an additional $2,700 per pump per year, or roughly $1.3 billion annually. Together, these changes would save $1.8 billion, Kernan said.

While many industries shy away from variable speed pumps, they make sense for irrigation systems, which are far more dynamic, Kernan said.

“Irrigation districts are changing all the time,” he explained. “They are modernizing and extending their pipes, adding new lines, and dealing with water restrictions that force them to alter pressure and water volume. Installing a VFD enables them to accommodate those changes without changing their pump. By using VFDs, they are future-proofing their system.” 

By matching system output to demand, VFDs can also provide better pressure. “My father-in-law has a farm in central Oregon that just switched to a closed pipe from an open canal. The pipe uses a central VFD pump to deliver pre-pressurized water he can run through his crop sprinklers. When he looked at his electricity bill after the first year, he found that he was saving $400 per month by not pumping water from the canal himself.”

Diesel

Not all pumps use electricity. More than 150,000 of them run on fossil fuels, about two-thirds on diesel, and 20 percent on natural gas. The remainder use liquid petroleum, propane, butane, and gasoline.

None are very efficient. Consider, for example, diesel pumps. Diesel engines are only about 40 percent efficient and that is before considering pump efficiency. That makes them less than half as efficient as today’s energy-efficient pumps. This shows up in operating costs. An average diesel ag pump, based on USDA data, costs about $13,336 per year to operate compared with $5,620 for an electric pump, that’s a $7,716 annual savings.

This seems like a slam-dunk case to replace diesel pumps with their electrical cousins. It is not because most fuel-based pumps are located in remote locations. Stringing electrical service out to them can be expensive—though $7,716 in annual savings might justify that kind of project.

Another possibility is to electrify pumps by linking them to renewable energy sources with a tank to create enough head for an irrigation system. U.S. farmers operate 4,500 of these direct solar power pumps and they are increasingly popular in California. Other states in the Wind Belt, like Iowa, Kansas, Dakota, and Texas, could use wind turbines rather than solar panels to do the same thing.

The Farm Bill

Kernan is quick to note that Cadeo’s pump study does not try to estimate the size of a true market for irrigation pumps. Instead, it attempts to assess the potential for cost, energy, and carbon savings from switching to more efficient electrical pumps and upgraded irrigation systems.

At $2.8 billion, that number is big enough to capture the attention of irrigation co-ops that are facing drought and water restrictions, as well as hard-pressed farmers and utilities.

This could lead to new programs and incentives that target pumps in the Farm Bill, an impending bill that Congress passes every five years. The bill allocates money to farmers and programs, such as the Environmental Quality Incentives Program, operated by the U.S. Department of Agriculture.

That would be a win-win for everyone, from farmers and utilities to pump manufacturers, distributors, and engineering consultants who can capitalize on this surprisingly large and rapidly changing market.

Learn more: https://www.pumps.org/irrigation-efficiency/

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