Future of hydroelectricity clouded by climate change – it’s also essential for the US electric grid | Opinion

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Caitlin Grady, Penn State and Lauren Denis, Penn State

Water in Lake Powell, one of the nation’s largest reservoirs, has fallen so low amid the western drought that federal officials are use of emergency measures to avoid the shutdown of hydroelectric power at the Glen Canyon Dam.

The Arizona Dam, which supplies electricity to seven statesis not the only troubled US hydroelectric plant.

The iconic Hoover Dam, also on the Colorado River, has has reduced its water flow and electricity production. California shut down a hydroelectric plant at Oroville Dam for five months due to low water levels in 2021, and authorities have warned that the same could happen in 2022.

In the Northeast, another kind of climate change problem has affected hydroelectric dams – too much rainfall at once.

The United States has more than 2,100 operational units hydroelectric dams, with locations in nearly every state. They play a vital role in their regional power grids. But most were built in the last century in a different climate than they face today.

As global temperatures rise and the climate continues to change, competition for water will increase and the way hydroelectric supply is managed within regions and across the electric grid in the United States will need to evolve. We study the country’s hydropower generation at the systems level as engineers. Here are three key things to understand about one of the nation’s oldest sources of renewable energy in a changing climate.

Hydropower can do things other power plants can’t

Hydroelectricity contributes 6% to 7% of all electricity production in the United States, but it is a crucial resource for the management of American electrical networks.

Because it can be turned on and off quickly, hydropower can help monitor variations in supply and demand from minute to minute. It can also help electrical networks bounce back quickly when power outages occur. Hydroelectricity accounts for approximately 40% of the installations on the U.S. electric grid that can be started without additional electrical power for a period of time. Blackoutpartly because the fuel needed to generate power is simply the water in the tank behind the turbine.

Tourists look at an old turbine that has been replaced at Glen Canyon Dam.
AP Photo/Felicia Fonseca

Moreover, it can also serve as a giant battery for the grid. The United States has more than 40 pumped hydroelectric plants, which pump water uphill into a reservoir and later send it through turbines to generate electricity as needed.

So while hydroelectricity is a small part of generation, these dams are integral to maintaining the electricity supply in the United States.

Climate change affects hydropower in different ways in different regions

Globally, drought has already reduced hydropower generation. How climate change affects hydropower in the United States, the future will largely depend on the location of each plant.

In areas where snowmelt affects river flow, hydroelectric potential is expected to increase in winter, when more snow falls as rain, but then decrease in summer when less snow remains to become. melt water. This pattern is expected to occur across much of the western United States, accompanied by worsening multi-year droughts that could reduce part of the hydroelectric productiondepending on how much storage capacity tank a.

The Northeast has a different challenge. There, extreme rainfall that can cause flooding is should increase. More rain can increase the power generation potential, and there is discussions on upgrading more existing dams to generate hydroelectricity. But since many dams there are also used for flood control, the possibility of producing energy of this increased precipitation could be lost if the water is released through an overflow channel.

In the southern United States, decrease in rainfall and intensification of drought are expected, which will probably lead to a decrease in hydroelectric production.

Some network managers face greater challenges

The effect of these changes on the national power grid will depend on how each part of the grid is managed.

Agencies called balancing authorities manage electricity supply and demand in their territory in real time.

The largest balancing authority in terms of hydroelectric generation is the Bonneville Power Administration in the Northwest. It can generate about 83,000 megawatt hours of electricity per year at 59 dams, mostly in Washington, Oregon and Idaho. The Grand Coulée dam complex alone can produce enough energy to 1.8 million households.

Much of this area shares a similar climate and will experience climate change much the same way in the future. This means that a regional drought or a snowless year could hit many Bonneville Power Administration hydroelectric generators at the same time. Researchers have found that the climate impacts of this region on hydropower present both a risk and an opportunity for network operators by increasing management challenges in summer but also reducing electricity shortages in winter.

The balancing authorities and the number of hydroelectric plants in each.
Lauren Denis, CC BY-ND

In the Midwest, it’s a different story. The Midcontinent Independent System Operator, or MISO, owns 176 hydroelectric plants in an area 50% larger than Bonneville, from northern Minnesota to Louisiana.

Because its hydropower plants are more likely to experience different climates and regional effects at different times, MISO and like-scope operators have the ability to balance hydropower deficits in one area with production in other areas. .

Understanding these regional climate effects is increasingly critical for planning electricity supply and protecting grid security, as balancing authorities work together to keep the lights on.

More change is coming

Climate change is not the only factor that will affect the future of hydropower. Competing demands already influence whether the water is allocated for electricity generation or other uses such as irrigation and drinking.

Water laws and distribution also change over time and change the way water is managed by reservoirs, which affects hydroelectricity. The increase in renewable energy and the possibility of using certain dams and reservoirs for energy storage could also change the equation.

The importance of hydroelectricity to the US power grid means that most dams are likely to remain, but climate change will alter the way these plants are used and managed.The conversation

Caitlin Gradyassistant professor of civil and environmental engineering and associate researcher at the Rock Ethics Institute, Penn State and Lauren DenisPh.D. Student in Civil Engineering and Climate Sciences, Penn State

This article is republished from The conversation under Creative Commons license. Read it original article.

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