Where can you drop a massive new 300 megawatt hydropower plant without anybody noticing? That’s a good question these days. Renewable energy can hit the same pushback that nuclear energy and fossil fuel encounter when the topic turns to planning for new generation. New transmission lines can cause headaches, too.
Finding new sites for hydropower is an especially taxing endeavor, considering the technical, environmental, and political challenges involved. That goes double for new hydropower projects tricked out with a pumped hydro element for energy storage. With that thing about “pumped” in mind, let’s take a look at Duke Energy’s latest hydropower project in South Carolina.
The Hydropower “Water Battery”
For those of you new to the pumped hydro topic, the idea is relatively simple.
When demand for electricity is low, you can use excess generating capacity to pump water from a lower source up to an upper reservoir. When the grid needs more electricity, gravity does the heavy lifting: you release water from the upper reservoir and use it to run turbines in a hydropower plant.
In effect, you have a giant water battery, or as some call it, an energy sponge.
How giant? Well, as much as we here at CleanTechnica love to enthuse over the latest breakthrough in lithium-ion energy storage and other cutting edge technologies, in terms of sheer volume nothing comes close to the simple water battery — at least, not yet.
The US Hydropower Association paints this picture:
Pumped storage today makes up 97 percent of utility-scale energy storage in the United States at 42 sites with a total of 23 GW of capacity.
As for the bad news, some analysts are finding evidence that utility scale energy storage creates an economic incentive for extending the lifespan of fossil and nuclear power plants. That’s because power plant operators can generate more electricity than they normally could during non-peak hours, as long as they have a place to store it. Then, they can sell it off during peak hours when rates are higher.
That’s something to keep in mind, though it’s becoming less of a concern as low cost renewables push other sources out of the picture.
Duke Energy’s Bad Creek Pumped Hydropower Plant
That finally brings us around to Duke Energy’s Bad Creek pumped hydropower plant.
Somehow this project has been sailing under the CleanTechnica radar, so a bit of catchup is in order.
The Bad Creek facility is located at Lake Jocasse, in South Carolina’s Devil’s Fork State Park. It was completed in 1991 at a cost of $1 billion, as one of the first modern hydropower plants in the world with a pumped storage element.
Park visitors can take boats on the main reservoir (aka Lake Jocasse), though officials warn boaters to be wary of fluctuating water levels. What visitors can’t do, by and large, is view the storage reservoir. It was constructed on top of a nearby mountain and can’t be seen from the rest of the park.
After a near 30-year run the plant is due for an overhaul, and that presents a major opportunity for Duke. Instead of simply replacing the existing equipment, the company is embarking on an upgrade.
The result is that Duke is essentially building 300 megawatts in hydropower capacity without building a new hydropower plant.
How is that even possible?
Kim Crawford and Randy Wheeless of Duke Energy spent some time on the phone with CleanTechnica last week to explain.
As Crawford described, the original facility was constructed with pump turbines designed in the 1970s and 1980s. In the intervening decades, the technology and materials have improved significantly.
Replacing the plant’s four pump turbines with up-to-date equipment is the main part of the project in terms of increasing capacity. If all goes according to plan they will be brought on line one at a time, with the first one in 2020 and the final upgrade in 2023.
Meanwhile, the facility will also get new generators and transformers, and a new output circuit among other refurbishments.
Doing more within the same footprint was the theme that Crawford and Wheeless emphasized, and you can expect to see more of that as the renewable energy field matures.
In recent years, for example, technology improvements for wind turbines have also made it economical to repower existing wind farms to ramp up capacity. Repowering existing solar farms is also beginning to catch on.
None of this is good news for the US coal industry, or for that matter, nuclear energy fans.
One faint bright spot for coal is the idea that a raft of nuclear power plant closures in upcoming years could force grid operators to rely more on coal, at least temporarily.
However, that hope could dim if the repowering market takes off, adding more juice to the renewables.
With that in mind, consider look at the latest AP report about the notorious Navajo Generating Station coal power plant in Arizona (follow the link to support local news!).
Among the top single greenhouse gas emitters in the US, Navajo is on the chopping block mainly due to competition from cheap natural gas.
Its current owners have given up the ghost and voted to close the plant, but there is potential interest from a buyer, Middle River Power. The company is formulating plans to keep it running — but only at half its current capacity.
For that matter, it’s unclear if Middle River could find anyone to buy electricity from Navajo, so stay tuned.
Part of the plan is to adjust generating hours, which could mean that Middle River is eyeballing an energy storage opportunity, so stay tuned for more on that score.
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Image (screenshot): via Duke Energy.