Water is key to life. We all know that humans are mostly water, and staying hydrated is a critical part of survival and longevity. But water can do much more than keep us hydrated and healthy. It can also be a powerful energy source.
In fact, 93% of all grid-scale energy storage capacity nationwide comes from hydropower. (“Hydro” is the Greek word for water and power equates to energy.) These systems provide renewable, sustainable, and independent energy. But they’re still not at their peak potential due to issues like cost, geological restraints, and more.
In the fight against climate change, pumped hydro storage (PSH) is a type of eco-friendlier power with great potential. So, what is this energy storage process that’s often called a “green battery?”
Continue reading to learn more about pumped hydro storage, its pros and cons, and its potential future advancements.
What Is Hydroelectric Energy vs. Pumped Hydro Storage?
First things first. When you hear terms like hydropower, hydroelectric energy, and pumped hydro storage, some people might use them interchangeably. However, they’re not all exactly the same thing. They all have hydro (water) in common yet there are nuances among them.
As an umbrella term, hydropower can encompass these different ways of using water as a renewable energy source. Hydroelectric plants are where water flows into a river away from a dam never to return. On the other hand, a pumped hydro storage plant collects water from an upper reservoir and pumps it back for as long as the plant is in operation.
How Does Pumped Hydro Storage Work?
Pumped hydro storage uses two water reservoirs at different elevations. The power station passes the water through a turbine to capture its energy as it flows from the higher reservoir to the lower reservoir generating electricity.
The PSH must then use some of this stored energy to pump water back to the upper reservoir. After completing this cycle, the PSH has a reserve energy storage capacity to release as needed.
Two types of pumped hydro storage exist — an open-loop and closed-loop system. An open loop connects to an outside body of water, such as a river, stream, or channel. A closed loop connects to a body of water with no outside connection, such as a pond, lake, or manmade reservoir.
What’s the History of Pumped Hydro Storage?
Water has been a valuable energy source for thousands of years, but the first ever electrical application came in 1880, according to the EPA. This application lit up a theater in Grand Rapids, Michigan. Then in 1893, the first-ever commercial hydropower plant — the Redlands Power Plant — was built in California.
From this technology came what we now know as pumped hydro storage in 1930. This plant, known as the “Ten-Mile Storage Battery,” was built in Connecticut to help meet the power demands in the area and help with water shortages.
Today, America is home to 43 PSH plants with enough storage capacity to power more than 16.7 million homes. That’s some 94% of total capacity of energy storage plants nationwide, according to the National Hydropower Association. And we’re not done yet. Another 67 PSH projects are in development across the nation capable of 50 gigawatts of storage.
Pumped Hydro Storage Locations
One downside to PHS plants is their need for specific terrain to function. They require two bodies of water at varying elevations and ideally a connection to a river. This limits where companies can build these plants.
A map of potential PHS sites shows the largest concentration in the Midwest and California due to the mountain ranges. A second, smaller concentration of potential sites exists in the mountain ranges between Pennsylvania and northern Alabama and Georgia.
Why Are Pumped Hydro Storage Plants Called “Green Batteries”?
PHS facilities aren’t like a traditional power plant, which offer a steady stream of power to a location. Instead, pumped hydro storage is more of a supplemental energy source — a battery backup, so to speak. This is why many experts refer to them as “green batteries”.
This means they are ideal for electricity grids that rely on solar and wind power. These power plants can store energy from water movement and release it if the demand for power exceeds the capabilities of the solar or wind power plant.
PHS systems can also provide green electricity at times when winds are low, or conditions aren’t favorable for solar power. As PHS becomes more widely adopted, it could aid in the shift to reliable, interruption-free solar and wind energy without the need for fossil-fuel or nuclear backups.
Is Pumped Hydro Storage Effective?
In short, pumped hydro storage is very effective. In fact, it’s over 80% energy efficient. While that’s not a perfect 100%, consider that other stored electricity systems have significantly lower efficiency. For instance, hydrogen is at 40 to 60% energy efficiency, compressed air is at 60 to 65%, and flow battery is as low as 70%.
How does that translate to actual time? The average PSH plant can provide about 10 hours of electricity, which is 40% more than the typical lithium-ion battery.
How Long Does a Pumped Hydro Storage System Last?
The average PSH plant can deliver 10 hours of electricity per 24 hours. Moreover, PSH facilities actually have very long lifespans that can last 50 to 100 years. This makes them a long-term investment that delivers decades of returns.
What Are the Pros of Pumped Hydro Storage?
Pumped hydro storage poses a range of benefits to the environment and more. Let’s review some of the upsides to PHS.
Sustainable, Renewable Energy
Because a PSH facility relies mostly on water — a renewable resource — they’re among the most sustainable power sources. This creates a virtually endless loop of water and electricity.
Power Supplementation
Because PSH systems are not part of the traditional power grid, power outages don’t impact them. This means their stored power can provide backup electricity during a power outage in the electrical grid.
Clean Domestic Power
After construction is complete, hydropower has no direct waste byproducts. This means it’s a clean energy source relative to fossil fuels like coal and natural gas. And because it doesn’t rely on fuels from other countries, pumped hydro storage is a domestic energy source that has no international interference.
Recreational Activities
When a PSH is completed, the public generally has at least some access to the area. This opens that body of water up to recreational activities, such as fishing, boating, and more. This can sometimes bring much-needed tourism activities to an otherwise unknown area.
Disaster Preparedness
The dams in PSH reservoirs can control water levels, helping mitigate the chances of flooding in extreme weather. But they can also act as massive water holds in the event of a water shortage.
Low Maintenance Costs
PSH facilities have the lowest levelized cost of electricity (LCOE) compared to all other electrical energy storage technologies. This makes them a cost-effective option for lower long-term budgets.
Well-Tested
Hydropower has been around for over a century, so it’s been tested and proven effective. But it also has lots of room for advancement as technology continues improving.
What Are the Cons of Pumped Hydro Storage?
Plenty of benefits exist to using pumped hydro storage, but it’s not perfect. Here are some of the downsides facing PSH electricity production.
Startup Costs
While maintaining a PSH facility is relatively cost-effective, pumped storage projects have high startup costs. On top of that, finding suitable land large enough with the right topography to house a reservoir, the facility, and all the other needs can present a challenge in meeting large-scale electricity demand.
Built-In Energy Loss
Energy loss happens in any energy storage system. In the PSH setup, though, this energy loss is a part of the design. To restart the power-generation cycle, the PSH facility must use some stored electricity supply to pump the water back up to the upper reservoir. This amounts to about a 20% energy loss.
Impact on Water Life
While the overall environmental impact is low, building the dams needed to create a PSH facility can impact the migratory patterns of fish. It can also connect to other waterways that may introduce non-native aquatic species that can threaten native species.
Subject to Climate Change
Climate change can lead to massive droughts, which can result in reduced water levels in a PSH facility’s reservoirs. This can result in the facility not operating at peak efficiency or not functioning at all in extreme cases.
What Are 3 Major Disadvantages of Using Hydropower to Produce Electricity?
PSH facilities fall under the grander hydropower umbrella, and projects share many of the same issues as pumped hydro storage facilities. The three main problems facing hydroelectricity are as follows:
- Impact on the surrounding environment: No matter what hydroelectric plant is built, it will typically affect the natural waterflow in the area. With PSH plants, this can impact fish migration, but it can also displace humans and other wildlife.
- Costs are high: PSH facilities are expensive, but this applies to all hydroelectric power plants. While their long-term costs are low, the upfront investment is significant.
- They depend on the environment: All hydroelectric plants rely on a steady stream of flowing water to generate electricity. If this flow stops, so does power generation. Climate change is known to cause massive droughts, which can leave these plants with insufficient water to generate electricity, rendering them inefficient or useless.
What’s the Future of Pumped Hydro Storage?
While nearly all grid-scale energy storage capacity in the U.S. is pumped storage hydropower, it still needs plenty of advancement to maximize its potential. Let’s review a few of the most significant advancements that can make pumped hydro storage more effective and feasible.
Eliminating the Powerhouse
In current setups, pumped storage facilities use reversible pump turbines underwater and above-ground motor generators stored in a powerhouse. This added powerhouse leads to increased construction and maintenance costs.
New submersible pump turbines and motor generators would eliminate the need for powerhouses and reduce construction costs. This means these PSH facilities will need less space to operate, potentially making it possible to build them where it was once not feasible.
Using Natural Geology
A new concept called geomechanical PSH involves pumping water through rock layers, keeping it under constant pressure until a valve opens. Opening the valve would pump the pressurized water through turbines without requiring different elevations to create pressure. This also makes areas once unsuitable for PSH facilities prime candidates, and many of these areas would have lower pumped storage plant project costs.
Leveraging Decommissioned Pit Mines
Decommissioned pit mines are essentially massive, unfilled holes. If a pumped hydro plant system is installed on one of these sites, one of the huge expenses is already covered: digging the hole for the reservoir. This would save time and money.
Can Pumped Hydro Storage Save Energy?
With the ability to convert flowing water into electricity and store it for future use, there’s no question about whether pumped hydro storage can save energy. It certainly can.
On top of that, it’s also a renewable energy source, an independent energy source, and, for the most part, a clean energy source. Of course, it’s not without its downsides, such as cost, energy loss, and environmental impact. However, technological advancements are in the works to help alleviate some of these issues.
Pumped hydro storage could eventually be a way for the masses to save a lot on their energy usage. Until then, you may want to consider switching to a green energy plan. It could lower your electricity bill and offset your carbon footprint in the fight against climate change.
Brought to you by justenergy.com
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- Source: https://justenergy.com/blog/pumped-hydro-storage-what-is-it-and-can-it-save-on-energy/
