Hydropower’s Future Is Clouded by Droughts, Floods and Climate Change – It’s Also Essential to the US Electric Grid

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Yves here. As far as I can tell, many green energy planner and proponents correctly regard hydropower as a very desirable source, since it can satisfy base load needs. Hence the prospect of it diminishing is troubling, since alternatives either rely on storage (which creates additional environmental costs) or do other sorts of damage.

By Caitlin Grady, Assistant Professor of Civil and Environmental Engineering and Research Associate in the Rock Ethics Institute, Penn State and Lauren Dennis, Ph.D. Student in Civil Engineering and Climate Science, Penn State. Originally published at The Conversation

The water in Lake Powell, one of the nation’s largest reservoirs, has fallen so low amid the Western drought that federal officials are resorting to emergency measures to avoid shutting down hydroelectric power at the Glen Canyon Dam.

The Arizona dam, which provides electricity to seven states, isn’t the only U.S. hydropower plant in trouble.

The iconic Hoover Dam, also on the Colorado River, has reduced its water flow and power production. California shut down a hydropower plant at the Oroville Dam for five months because of low water levels in 2021, and officials have warned the same thing could happen in 2022.

In the Northeast, a different kind of climate change problem has affected hydropower dams – too much rainfall all at once.

The United States has over 2,100 operational hydroelectric dams, with locations in nearly every state. They play essential roles in their regional power grids. But most were built in the past century under 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 hydropower supply is managed within regions and across the power grid in the U.S. will have to evolve. We study the nation’s hydropower production at a 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

Hydropower contributes 6% to 7% of all power generation in the U.S., but it is a crucial resource for managing the U.S. electric grids.

Because it can quickly be turned on and off, hydroelectric power can help control minute-to-minute supply and demand changes. It can also help power grids quickly bounce back when blackouts occur. Hydropower makes up about 40% of U.S. electric grid facilities that can be started without an additional power supply during a blackout, in part because the fuel needed to generate power is simply the water held in the reservoir behind the turbine.

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

In addition, it can also serve as a giant battery for the grid. The U.S. has over 40 pumped hydropower plants, which pump water uphill into a reservoir and later send it through turbines to generate electricity as needed.

So, while hydroelectricity represents a small portion of generation, these dams are integral to keeping the U.S. power supply flowing.

Climate Change Affects Hydropower in Different Ways in Different Regions

Globally, drought has already decreased hydropower generation. How climate change affects hydropower in the U.S. going forward will depend in large part on each plants’ location.

In areas where melting snow affects the river flow, hydropower potential is expected to increase in winter, when more snow falls as rain, but then decrease in summer when less snowpack is left to become meltwater. This pattern is expected to occur in much of the western U.S., along with worsening multiyear droughts that could decrease some hydropower production, depending on the how much storage capacity the reservoir has.

The Northeast has a different challenge. There, extreme precipitation that can cause flooding is expected to increase. More rain can increase power generation potential, and there are discussions about retrofitting more existing dams to produce hydropower. But since many dams there are also used for flood control, the opportunity to produce extra energy from that increasing rainfall could be lost if water is released through an overflow channel.

In the southern U.S., decreasing precipitation and intensified drought are expected, which will likely result in decreased hydropower production.

Some Grid Operators Face Bigger Challenges

The effect these changes have on the nation’s power grid will depend on how each part of the grid is managed.

Agencies known as balancing authorities manage their region’s electricity supply and demand in real time.

The largest balancing authority in terms of hydroelectric generation is the Bonneville Power Administration in the Northwest. It can generate around 83,000 megawatt-hours of electricity annually across 59 dams, primarily in Washington, Oregon and Idaho. The Grand Coulee Dam complex alone can produce enough power for 1.8 million homes.

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

Balancing authorities and the number of hydropower plants in each. Lauren Dennis, CC BY-ND

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

Since its hydropower plants are more likely to experience different climates and regional effects at different times, MISO and similarly broad operators have the capability to balance out hydropower deficits in one area with generation in other areas.

Understanding these regional climate effects is increasingly essential for power supply planning 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 hydropower’s future. Competing demands already influencewhether water is allocated for electricity generation or other uses such as irrigation and drinking.

Laws and water allocation also shift over time and change how water is managed through reservoirs, affecting hydroelectricity. The increase in renewable energy and the potential to use some dams and reservoirs for energy storage might also change the equation.

The importance of hydropower across the U.S. power grid means most dams are likely here to stay, but climate change will change how these plants are used and managed.

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  1. Solarjay

    2 updates.
    1. One of hydropowers main benefits is that it is a demand generator. It can be turned up or down very quickly responding to grid load changes. Better than anything other than batteries.
    Generally hydro would not be considered a base load power plant.

    2. Black start is what happens when the grid goes down and you have to start it from zero. However most “generators” ( hydro, wind,or gas or coal plants) require an AC voltage signal to excite the field to get them to produce power.
    Most power plants have a stand alone diesel generator that does this. In the event of a complete power failure, this will be turned on, the main generators (powered by coal, gas, wind, hydro) will start see the AC which excites them and now be producing power.

    Inverters/batteries don’t need the backup generator as they can be grid forming due to there design.
    However almost all home solar inverters will not produce any power unless there is the grid, these types are non grid forming as a safety feature.

    1. Jacob Hatch

      Most large generators not only need a excitation power, but they also require a power factor to be present on the grid once connected or the voltage can not be kept stable and they will trip, this is particularly true of solar and wind. Pumped storage power plants are the best option for providing the power factor as they can run one pump/generator set coupled as a pump start up mode to a generator on site so they will spin up together, the pump set providing the power factor stability to the generator so when they reach the cycle speed to connect to the grid, the generator will not trip out upon connecting to the grid, nor trip when another large generator connects without which makes connecting further large generators to the grid an extremely tricky matter. Some hydro/electric stations can provide a similar start up, but their power factor ability is more limited, and because of costs, some were not designed to do so.

      Large battery power plant facilities are one item that is being researched as an important source of power factor / grid voltage stability as grids go more green, though there are risks there as well.

      1. scott s.

        This is something that bothers me about distributed solar where owners want the right to feed back into the distribution system for free, with no responsibility to maintain voltage, frequency, or power factor.

        1. drumlin woodchuckles

          Perhaps one could develop a concept of “distributed parallel solar”, where homedwellers put up their own solar panels and batteries to store and discharge their own electricity for use in their own separate free-standing DC appliances. These personal DC single-house systems could be rigidly air-gapped from the AC grid system, thereby not imposing those costs you referrence.

          If people needed more electroppliance-use at any one time than they were getting from their own standalone DC system of panels and appliances, they could turn on their stil-retained AC electroppliances and use must-be-paid-for AC grid power.

          Or if people insisted on not having to own any parallel DC standalone electroppliances, they could perhaps have just enough an inverter-system between their batteries and the house-wiring feeding their appliances to where they could run their appliances off their own stand-alone panel-battery system, and if they needed more power than that at any one instant, they could draw must-be-paid-for power from the must-pay-to-be-hooked-up-to AC power grid.
          And they would have zero ability to forcibly upload any of their own personal surplus power into the common grid.

          If this ” no responsibility” problem is indeed a problem, there is a way to avoid imposing it.

        2. Jacob Hatch

          They also use the grid for a back-up power supply. Most utilities charge a hook up and monthly minimum, but it’s never near the real cost to the grid of those resources. Most of this burden as a % of income is born by the poor, as as we know money talks, even more so in local government, there is no solution to this regressive tax.

          1. drumlin woodchuckles

            I know this is sincerely believed in by some, but I also know that this is a fake talking point invented by electric utilities to reject requests to buy power from rooftop suppliers and to reject calls for greater solarization of utilities, especially in the form of permission or even assistance to individual rooftop solarizers.

            Several years ago I read an article in Detroit Metrotimes about how DTE Energy was giving money to black-pastor-based community activity groups in Detroit and in return these black pastor-based community activity groups were lobbying against solar electric requirements on the excuse that ” the poor” don’t get the subsidies.

            If someone were to pay me a hundred dollars an hour to search through all the back issues of Detroit Metrotimes, I could look till I found it. I wouldn’t even try finding it on the search prevention/search obstruction engines of today.

            1. Jacob Hatch

              That they paid someone to lobby does not make it untrue, it just means that Detroit Electric wanted the profit from selling power to the rich too. Das Capital

              1. drumlin woodchuckles

                That they paid someone to lobby does not make it true, either. I regard it as a “wokewashed” fake talking point designed to obstruct the rollout of rooftop solar. I would like to see opposition to rooftop solar rollout crushed and smashed flat. I will not be extorted away from my desire by faked-up concern about ” the poors”. ” What about the children? What about the poors?” Sorry, no.

                If “bearing the cost of grid maintainance” is oh-so-very-much of a real concern as against just a fake talking point, let every kilowatt-hour sold contain a maintain-the-grid fee. Under such a billing model, those who use less electricity ( the poors) will pay less of the grid-maintainance fees.

                I remember one month many years ago . . . I apparently used so little electricity that month that DTE Energy told me on the bill that since I did not use enough electricity for them to be able to bother billing me for the amount of electricity use, they would bill me that month for the ” hook-up fee” to be on the grid. And I accepted that as being entirely fair. I remember that month’s electric bill as being something like $7.00 or so. That is entirely affordable to the poors.

        3. Solarjay

          Grid tie inverters don’t create voltage or frequency or a wave form. They mirror whatever the grid gives it. They push current back to the grid. These rules are set by IEEE and UL and approved by all utilities.
          California ( rule 21)and Hawaii (H14)have specific rules that require new inverters to provide PF support either leading or lagging, and voltage/frequency support controlled by the utility in case of need.

  2. Joe Well

    Yet another reason that tens of millions of people should not be living in such arid places.

    1. drumlin woodchuckles

      If those tens of millions of people are all gunned-up and heavily ammo’d, they may have something to say about that.

      1. John

        Lots of guns and ammo are no substitute for water whether to drink or create electricity.

        1. drumlin woodchuckles

          If a liberal fascist government tries to round up these tens of millions of people by violent force to put them into urban vertical barracks, they will fight back.

          If a liberal fascist government just figures out how to quietly abandon these areas and let their grids decay and die, most of the inhabitants will move to the feeding center barracks in the cities and some will take their chances on a zero-electricity suburban-slum-village civilization in the emerging suburban slum villages. They will harvest their own roofwater and live a zero-electricity life and so survival will not be a problem for them.

          1. Joe Well

            Serious question: are you are actually afraid of fed roundups of million of people? How would they even get the capacity to do that if they wanted to?

            And when has the federal government ever rounded up large numbers of people who weren’t Japanese Americans, indigenous people, or immigrants and their children? Or maybe, maybe, the few thousand who stood in the way of some development project. Even in all those cases, the numbers were never anywhere close to a million at a time.

            And yet the people who subscribe to this kind of conspiracy theory, by and large do not belong to any such vulnerable groups, quite the contrary.

            So where does the fear come from?

    2. drumlin woodchuckles

      To be clear, the enemies of suburbia want to round up and barrack-ize tens of millions of suburbanites from semi-humid and humid places.

      If your comment really was directed strictly to the people in arid places, there will be no need to “round them up at gunpoint”. Just let the power run out and the water run out. They will make their own choices at that point. They will discover that you can’t drill a well with a gun.

  3. Wukchumni

    We have one of the older hydroelectricity plants in Cali with ours dating from 1900, and its all about flumes with 3 of them diverting 2 forks of the Kaweah River to make power, kind of a perpetual motion machine until drought years, and it shut down in 2014-15 due to a lack of water, and will do so again after a pitiful winter.

    Has to be the same story right on down the line with other hydro in the Sierra

    There’s a number of natural springs along Mineral King Road and my favorite one has a pipe jutting out from rocks where the source is, ice cold water that would fill a Nalgene in 10 seconds, no need to filter.

    Many times it would flow through to the fall…

    Last year it went dry in July…

    It was dry last Sunday, in mid May

  4. Anthony G Stegman

    The Glen Canyon dam should be shut down, with the remaining water in Lake Powell sent down to Lake Mead. Glen Canyon is a spectacular place that should never have been flooded. Since the lake has been used to store excess water it makes little sense to maintain the dam when there is no excess water to begin with. Other sources of energy can be found to replace the hydroelectricity generated by the Glen Canyon dam.

      1. John

        If the current drought is in fact the opening act of a several hundred year drought, which has happened before and can happen again, no rescue plan is any more than a leaf in a whirlwind. Climate is changing. We can argue about causes and points fingers in blame, but the climate keeps changing and we do nothing of any importance to mitigate that fact. The “normal” we humans have enjoyed for most of our existence seems to be vanishing. We want to continue to live as we have. That is not possible, but I believe it will require some hard hard lessons before enough are convinced by reality to do what is necessary and there will be a rear guard heels dug in and shaking their fists at the heavens insisting that they can and will have what they want.

        1. Joe Well

          What about desalination? Not that I think our government is capable of delivering.

        2. drumlin woodchuckles

          That part of climate change being driven by man made carbon skyflooding can be mitigated or even reversed by man made carbon skydraining, if conducted soon enough and real enough.

          Assuming it won’t be, those climate changes man made by man made carbon skyflooding can be predicted as indeed they already have been, and people who choose to believe in “no such thing as manmade global warming” should be left alone to live out the meaning of their belief.

          That means that they should receive zero assistance of any kind when they experience the global warming disasters they affect to ” not believe in”.

  5. Carolinian

    No mention of the Southeast where the TVA is the big kahuna. But the TVA was always about too much water and seasonal floods as much as power generation (cue an excellent Elia Kazan/Montgomery Clift movie called Wild River). Will many of those Westerners be giving up their cowboy boots for bib overalls and juleps? Our local tycoons seem to think so but could be wishful thinking.

    1. ocop

      Hydropower in the Pacific NW has this same “problem” as TVA. The BPA and TVA hydro systems were both engineered with a primary function of flood control, with power as a very nice bonus for electrification and the war effort. And both, if I am recalling the maps correctly, should get somewhat wetter from climate change.

  6. PlutoniumKun

    Its not just the US. The melting of glaciers in the Himalaya has the potential to cause enormous energy stresses in an arc from Pakistan to China. Even if precipitation remains the same, its likely to be far more seasonal without ice mediating year round flows.

  7. drumlin woodchuckles

    What if America restored the beavers so totally that we got back to having 500 million working beaver dams?

    What if beaver-cheater pipes could be installed into all those dams, always drawing off “some” water but never draining the dam and chasing the beavers away?

    What if every beaver-cheater pipe outlet had a tiny nano-hydro nano-turbine in it to generate a little bit of electricity from the little bit of draining water? If 500 hundred million beaver dams had 500 million beaver cheater pipes with 500 million nano-hydro turbines . . . . how much electric power would 500 million nano beaverdam turbines end up to be yielding?

      1. drumlin woodchuckles

        No, because I was being straight-faced serious. It might be a silly idea, but I offer it in all sincerity in case there might be something there.

    1. heresy101

      The beavers may not be able to keep up with electricity that is generated from instream irrigation and water canal electric generators.


      “The investment follows two successful project deployments that have accumulated two years of commercial operation. The Monroe Hydro Project in Madras, Oregon is a first-of-its-kind design making use of an existing irrigation canal and Natel’s new, fish safe turbine technology to generate reliable, renewable energy. With the installation of the commercially released 1 MW class D190 RHT, the site now contributes 100% renewable energy to the local grid. The successful completion of the Monroe Hydro Project and the industry-leading fish passage testing that was conducted by Pacific Northwest National Lab extend Natel Energy’s work to make sustainable hydropower a large scale source of distributed, reliable, renewable energy.”

      “Natel’s Restoration Hydro Turbine is a compact propeller-style turbine with specially designed blades that allow fish to pass safely. The RHT has a compact footprint that reduces total installed cost and enables plant designs that maintain or improve river connectivity. The RHT is suitable for upgrading or repowering existing small hydro plants with modern, high-performance fish safe turbines; for adding a new generation to existing non-power dams; and for new hydro development through Natel’s Restoration Hydro design approach. Natel’s Upstream Tech HydroForecast solution enables more accurate forecasts of water flow, helping optimize power production from both RHT and conventional hydro projects; while the Lens solution delivers cost-effective, easily scalable monitoring of landscape change across large project areas to deliver effective natural resource management.”

      1. drumlin woodchuckles

        I wonder if these turbines could be made small enough to fit into a beaver-cheater pipe outlet flow stream.

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