by Doug Johnson: Hydro power is decreasing as climate change hangs the Southwestern US out to dry…

Awaken

News that Arizona’s Lake Powell is slowly but surely drying up has spread far and wide. The reservoir behind the 1,320-megawatt Glen Canyon Dam and power station, Lake Powell plays an important role in providing power for some 3 million customers in Arizona, Colorado, New Mexico, Utah, and Wyoming.

But this year, the reservoir has hit a historic low, due to ongoing drought conditions in the region that have been attributed, at least in part, to climate change. The dam may even stop producing power if the situation continues to worsen, and this issue is not an isolated one in the American Southwest.

The Colorado River, an important source for many dams and power plants in the region, has been wracked by drought for the past 22 years—some research even suggests that it is subject to the worst drought the area has seen in 1,200 years. Further, according to the US Drought Monitor, as of March 29, 88.75 percent of the Western US has been experiencing a moderate drought or worse. According to staff members at the United States Bureau of Reclamation (USBR), other dams in this be-droughted part of the country are seeing similar effects—though the officials also noted that each case is different.

According to Becki Bryant, the USBR’s Upper Colorado Basin public affairs officer, there are two main factors that impact hydro production. The first is the amount of water that passes through a dam’s generators. The second is the depth of the body of water that feeds the dams. Deeper bodies of water have more force behind the water rushing through and spinning the turbines of a generator.

Lake Powell and the Glen Canyon Dam make up an extreme case in the US. The dam’s minimum power pool (MPP)—the point at which hydropower can no longer be produced at the dam—is around 1,064 meters. Currently, it is sitting at 1,075 meters. Projections suggest that there is a 23 to 27 percent chance of hitting the MPP each year from 2023 to 2026, according to Bryant. Other parts of the Colorado River Basin, which is home to a few other dams, are being impacted by the drought as well. The 22-year drought has decreased the amount of energy produced in the area by 13.1 percent compared to the average annual energy production in the 12 years preceding it (from 1988 to 1999). “It is difficult to predict actual impacts beyond 2023, but this trend is anticipated to continue,” Bryant said.

California dreaming

In news that should shock no one in the state, California is also dry. However, the nature of California—which is home to many hydro operations—is somewhat different from Arizona, according to Steven Melavic, chief of power operations with the USBR’s Central Valley Project. Cary Fox, a team lead with the USBR, said that if the Shasta Powerplant’s reservoir were entirely full, it would be a 710-megawatt plant. Currently, the water in its reservoir is low enough that it’s expected to produce a low of around 380 megawatts by the end of the fall.

However, California’s reservoirs can be quickly replenished thanks to wet storms coming from the Pacific Ocean. “The reservoirs can rebound in a heartbeat. It’s a different kind of dynamic,” Melavic told Ars.

But Fox noted that the reservoirs really only have winter and fall to fill up again with precipitation. “If it does not rain or snow in the winter, that’s it. We kind of have one season… This year, it didn’t happen,” Fox told Ars.

Melavic added that in the past decade, California has had more dry years than wet. It’s hard to say what the future holds for its reservoirs and dams, but for this year, at least, the state isn’t expected to get better. “The averages have been against us over the last 10 years or so—pretty dry,” Melavic said.

Nevada’s Hoover Dam, a US landmark, also isn’t firing on all cylinders. Nevada, much like other parts of the Southwest, is in the grips of drought. As of February, Lake Mead, which provides the dam water, was sitting at an elevation of 325 meters. According to the USBR, the dam is expected to stop producing power at around 289.56 meters.

Hoover Dam’s normal capacity is 2,074 megawatts, according to an email from the USBR. As of last week, it was sitting at around 1,500 megawatts—a decrease of around 25 percent. A normal year for the dam would see 4.5 billion kilowatt-hours produced. Last year, production decreased by 22 percent to 3.5 billion kilowatt-hours, the USBR said.

What’s next?

Dominique Bain is the co-author of a 2018 paper on the impacts of drought and climate change on hydropower in the Southwestern US. (She wrote it as a Ph.D. student at Northern Arizona University’s School of Earth Sciences and Environmental Sustainability.)

The paper used modeling and Western Electricity Coordinating Council data to answer a question: What would happen to power production if the Southwest were to lose Lake Mead and Lake Powell? The research was based on what we knew in 2016 and 2017, but Bain noted that things have changed somewhat since then. Some coal plants have retired, natural gas is cheaper than anticipated, and there is more solar power. Also, battery tech has not developed as much as expected.

In any case, if the US were to lose Lake Mead and Lake Powell, the Southwest would still have power, but there would be trade-offs, Bain said. One thing hydro does particularly well is stabilize other forms of electricity production that rely on outside factors—solar only works when it’s sunny out; wind only works when it’s windy.

For example, Hoover Dam is often used to balance large solar operations in California and Arizona. When the Sun is high during the day and loads are relatively low, Hoover doesn’t produce much power. But when the Sun begins to set and loads increase with people returning home, watching TV, and making dinner, solar doesn’t produce as much power, and the dam produces more. This would be lost with Lake Mead.

According to Bain, a few things could be done to make up for a decrease in hydropower. Natural gas could help fill in the gaps, though this comes with obvious issues. She said that, at least for Hoover Dam, installing pumped storage hydro could work. This would involve using solar power (which can often be produced in excessive amounts) during the day to bring water at the bottom of the dam up to the top to run through it again. This does use energy, and evaporation can still result in water loss. But it means that water can be recycled for use later in the day when solar power isn’t at peak performance.

Another option would be to invest more in developing better utility storage batteries, which could store the power that the dam generates for later use. Bain noted that back in 2012 through 2014, grid-level storage batteries were anticipated to be a big deal, but they haven’t yet materialized, though efforts have been made. Bain added that batteries often have a limited lifespan, 10 years or less, and they are generally quite small. It’s possible that in the future, we will have better battery storage, but right now, “We’re just not seeing that,” Bain told Ars.

According to Bryant at the USBR, several measures have been undertaken in the Colorado River Basin. Though many of them were a part of regular maintenance and repairs, a few were performed directly in response to the drought. At Glen Canyon Dam, the turbine runners (the part of the machine that generates power by spinning with the movement of the water) saw a design update to make them more efficient, for instance. The USBR also continues to monitor the river system.

“[P]rotecting the elevations of Lake Mead and Lake Powell remains a top priority while working collaboratively with the Basin States and water managers toward solutions to protect the vitality of the Colorado River,” Bryant said.

Source: Ars Technica