ENERGY FROM RIVERS AND TIDES

A MONTH EARLIER, when the girls and I set a date to visit the Turners Falls Hydroelectric Dam, I called ahead and arranged to meet with the manager of the facility, Ralph Jones. Ralph agreed to meet us at what he called the Cabot Station, which houses the largest generators at the Northfield dam complex. He’d see us at the “fish ladder,” he said.

When we resume our journey after lunch, I follow his directions, passing through an open gate and parking above the river. Ralph is waiting for us there. He greets everyone and invites the girls to call him by his first name.

Then he turns and points at the fish ladder. Behind us, river water is channeled to the dam. Water runs into the top of the ladder from the channel. Then it’s carried across the spillway—a structure that controls how much water is released to flow down the river—in what looks like a chute. The ladder snakes back and forth as it gradually drops down to the level of the river below the dam.

“Do you know what this is for?” he asks.

The girls are silent for a moment, watching water cascade down the long trough. Then Julie pipes up. “I think maybe it’s a way for fish to get around the dam?” she suggests. “My brother Tom is a fisherman, and he asked me to find out what happens to the fish when they swim up to the dam.”

Sun, Wind, and Water by Mon Cochran
The Cabot Fish Ladder
Fish swim up fish ladders in order to get around dams.

 
Ralph nods appreciatively. “You are correct,” he says. “Each of those boxes of water in the ladder is a little pool. There’s not much difference in height from one little pool to the next—only twelve inches—so the fish can jump from one pool to the next. The pools are like little steps on a ladder, so we call this a fish ladder.”

“Can you see the fish as they climb the ladder?” Natasha wonders.

“Oh, sure. Inside this building, a window looks out onto the pool at the bottom of the ladder, and you can watch the fish swim by on their way upstream to spawn.” He points at the nearby building. “I’ll show you the window in a minute. But we probably won’t see any fish because most of them swim upriver in the spring, between April and June. A lot of school groups come to visit then.”

Amaya points at the old brick building. “Is that where the generators are?”

Looking Inside the Fish Ladder: This fish is a shad on its way up the fish ladder.
Looking Inside the Fish Ladder: Eels also use the fish ladder to bypass the dam.

“It is. Do you want to take a look?”

“Oh yes!” she replies breathlessly. “That’s my part of our water power project!”

After a quick stop at the fish-viewing window, Ralph leads us down a hallway and into a small room. A large-screen TV attached to a laptop sits on a conference table with comfortable chairs around it. Inviting us to sit, he launches into a description of the whole Turners Falls/Northfield hydropower complex.

“We have two generating plants here,” he explains. “This building, Cabot Station, contains most of our turbines. It was built a hundred years ago, so it’s been generating electricity for a long time! Station Number One, farther upriver, is smaller. The big dam at the falls channels water into what we call the power canal, which carries it to our generators.”

Natasha raises her hand. “We had a picnic lunch up above the dam, so we could see water going into that canal.”

“Good.” Ralph turns on the TV and brings up a map on the screen. “Here you see the Cabot Station, where we are now.” He points to the building. “Above the dam is what we call the Impoundment, which is like a big lake of water backed up behind the dam. That’s the water you looked out on during your picnic.” His hand moves to the big pool of water at the top of the map.

“And partway along the Impoundment, off this map, you come to our Northfield Mountain Pumped Storage Plant. Back in the 1960s, they tunneled into the mountain and built this amazing underground facility.”

Sun, Wind, and Water by Mon Cochran
The Turners Falls Dam Complex
This map shows the dam, the electricity generating stations below the dam, and the two fish ladders.

 
At the mention of Northfield Mountain, Amaya straightens up. “I read about that plant!” she announces proudly. “That’s where you pump water up to a lake at the top of the mountain, and then run it down a tunnel and through a generator, to make electricity when we need more.”

Ralph smiles and nods. “Exactly right.” Now let’s watch a video that shows how all these parts of the Turners Falls project work together.” Turning to the computer, he starts the video, and the girls watch intently.

 
It All Begins with Rain...on Northfield Mountain

As soon as the video ends, Julie’s hand shoots up. “Mr. Jones … I mean, Ralph?” she says urgently. “The man talking said that the water turns the turbines to make electricity—kind of like with a water wheel. And it looks like the turbine is attached to something that spins around and makes the electricity. But what’s a turbine exactly?”

Ralph grins at her. “Well, you already sort of know, Julie,” he says. “A turbine is any kind of machine with a wheel in the center and blades sticking out of it. Then water or steam or something else flows over those blades with a lot of pressure and turns the turbine. So a water wheel is really a kind of turbine!”

Julie looks at me, then replies, “This morning, we were talking about how a generator works when it’s attached to a water wheel. Didn’t the guy in the video say that your turbines are attached to a generator?”

I don’t think Ralph was expecting that question, but he continues. “You’re remembering right,” he tells Julie. Addressing all the girls, he asks, “Did you talk about the next step: how the spinning generator makes electricity?”

Natasha answers this time. “We talked about how a generator works with magnets. And how the electrons in atoms are what make electricity.”

Ralph nods. “Your grandfather told you that a generator uses magnets to knock electrons loose and send them along a wire as electricity, right?”

“Yes, he did,” Julie confirms. “Gramps said that inside the generator, at the end of the bar you call a shaft, is a magnet. The magnet is spinning really fast as it moves past some coils of copper wire. That makes electrons in the wire come loose, so they flow out of the generator and into the big wires that go into our homes, to run our lights and furnace and other stuff.”

A generator uses magnets to knock electrons loose.

The Turbine with its Generator
Water flowing through the turbine hits the blades and spins the generator. The magnets in the rotor knock electrons loose from the copper wire in the stator.

“Very good!” Ralph brings a picture up on the screen. “Here’s a picture of how the generator and turbine work together.”

Amaya’s hand goes up. This is the part of the water power project she’ll be presenting to their class, and she wants more details. “I see where the water goes in and hits the blades,” she begins. “And I see the shaft that connects the turbine to the generator. The thing called the rotor—is that where the magnets are?”

Ralph smiles at her enthusiasm. “That’s right. The rotor moves, or rotates, like the word sounds. And outside it is the stator, which is stationary—it stays still. The stator is wrapped with really long strands of copper wire. When the magnet in the rotor spins past the copper wire, it pushes electrons in the copper along the wire. That stream of electrons is electricity.”

“How come you use copper?” Natasha asks.

“Well, every kind of metal is made of atoms,” Ralph explains, a little surprised that the girls are asking such good questions. “And all those atoms have electrons flying around in them. But in some metals, the electrons are easier to knock loose from their atoms, compared to other metals. Copper has very loose electrons, so it’s quite easy to pull them with a magnet into a stream of electricity.”

“Wow!” Julie says, impressed. “That’s cool. Can you show us the generators here in this building?”

“I can and I will. Any more questions about what you saw in the video?”

“Will we get to visit the Northfield pumped storage place?” Natasha wants to know. “It looks like something you’d see in a movie.”

“If you want, we can drive up there after we visit the generators,” Ralph offers, glancing at me. “Follow me to the generator room.”

The electrons in copper wire are easy to knock loose with a magnet.

He leads us down a hall and through a large door. We find ourselves on a balcony overlooking a huge room where six large round blue machines stand in a line. Each one is the size of a small flying saucer. And the noise they make is so loud that we have to shout to hear each other. For a couple of minutes, the girls and I just watch, taking in the immense size of the room and the roar of the machines.

“Down below the floor, is water from the river flowing through generators?” Natasha finally asks.

“It is,” answers Ralph. “In the video, you saw how the water turns the generator. That’s what is happening underneath each of the six metal housings you see here. Water rushes past the turbine blades in a tunnel under the building. The turning blades are attached to a shaft that runs up through the floor to the rotor. The stator and rotor are inside the housing, above the floor.”

There isn’t much more to see in the turbine room, and it’s really noisy, so we follow our guide back outside. Ralph hops into his truck and we follow him in the car as he drives north along the Connecticut River, then across the river to Northfield Mountain, where the pumped storage facility is.

First we stop beside an enormous solar farm. The girls and I jump out and join Ralph at the fence surrounding the panels. Natasha starts snapping pictures with her iPad.

Julie is the first to speak. “Wow,” she mouths almost to herself. “I didn’t know this was here. This is huge.”

“The farm is as big as six football fields, and it contains eighteen thousand solar panels,” Ralph says proudly. “It’s one of the largest solar energy farms in New England.”

The solar farm is as big as six football fields.

“I can’t wait to tell Tom and his friends about this.” Julie jogs along the fence line, scanning the panels. “In their science project, they’ve been learning about solar energy and how solar panels work.”

Amaya turns to Ralph with a question. “We saw in the video that you have to pump water through a tunnel up the mountain and into a reservoir, before you can run it down through the generators inside the mountain. Do these solar panels make the electricity you use to pump that water up?”

Ralph thinks for a minute before answering. “Well, … in a way,” he finally says. “Do you know what the electricity grid is?”

Amaya thinks, then says, “Isn’t that where all the electric wires and the big power lines connect together?”

“That’s right,” he replies, “and those power lines bring electricity from the power plants to people and factories in places all over the country.”

The Electrical Power Grid
In this illustration the power plant is the Turners Falls generators and the energy storage facility is the Northfield pumped storage facility.

 
Ralph goes on. “So here’s where the grid comes in. We don’t use the solar-farm electricity directly to run the pumps in Northfield Mountain—because we only need to pump water up to the reservoir at certain times. Instead, we send that electricity into the grid, then draw electricity out of the grid when we need it to pump water.”

Julie chimes in. “The problem is that most of the electricity in the grid comes from burning coal and gas, right? So we need to build more big solar farms, and put up big windmills in the ocean, and make electricity using water power—so we can stop burning fossil fuels that send carbon dioxide into our atmosphere.” I’m happy that she gets the connection between the clean energy systems we’re seeing today and the bigger picture of the grid.

Natasha looks puzzled. “So how about the water up in the reservoir? When do you use that water to make electricity?” she asks.

“Let’s suppose one of the big power plants that produces electricity for New England stops working for some reason,” Ralph begins. “But say this happens during a weekday, when cities and towns need lots of electricity to keep the lights on and people’s computers running.

“That’s when they call us and say, ‘Emergency! Turn on the Northfield turbines!’ We are a backup power source, to use in emergencies.”

Natasha turns this idea over in her mind and puts some things together. “Okay, this solar farm only makes electricity during the day, when the sun is shining.” She continues: “The pumped storage plant can make electricity with water during the night, when the solar panels aren’t working. So they can work as a team—one working during the day and the other at night!”

“Good thinking!” Ralph approves. “We need to figure out how different ways of making electricity can work together, like our different systems do here.

“The dam makes electricity both day and night. But solar farms can only work when the sun is shining, and wind generators work only when the wind is blowing. Our Northfield reservoir acts like a big battery that we turn on just when we need it. We also need to find more ways to store the clean electricity we make.”

Our Northfield reservoir acts like a big battery.

By now it’s quite late in the afternoon, and the autumn sun is sliding toward the west.

“We need to start back toward Boston,” I say, thanking Ralph for giving us such a great tour.

“I wish I could have taken you inside the mountain to see the pumped storage plant,” he says, “but you got an idea of it from the video. We could drive up and take a look at the reservoir if you’d like?”

“Thanks, but I need to get these girls back to their families for dinner.” We all shake Ralph’s hand, the girls offering their thanks as well, and head back to the car.

Northfield Mountain Pumped Storage

This is the reservoir on top of Northfield Mountain.

Northfield Mountain Pumped Storage

Here are the tunnel and road leading inside the mountain.

Northfield Mountain Pumped Storage

Now we are inside the mountain.

Northfield Mountain Pumped Storage

These are the generators deep inside the mountain.

On the long drive home, the girls are tired from taking in so much new information, but excited to have gathered so much material for their project. Natasha has taken lots of pictures to illustrate what they’ve learned. In the back seat, she and Amaya are thumbing through the images.

Julie, sitting beside me, is remembering how the fish swim past the dam on their way upriver. “I wish Tom had been there to see the fish ladder,” she says, untangling her hair from the seatbelt. “I’m glad they built it, so the shad and other fish can get to where they lay their eggs.”

I’m proud that my granddaughter realizes how putting dams on a river can affect the fish that live there. “Some of the fish don’t make it,” I tell her. “Dams are good for making clean electricity, but they are a real problem for fish that want to travel up and down the river.”

Julie falls quiet. Maybe she’s thinking about the fish. Then her face brightens.

“Do you want to hear what I’ve learned about using the tides to make electricity?” she asks.

“Definitely. How does that work?”

“Actually, it’s kind of like what we saw today, with the dam and the generator,” Julie explains. “And even kind of like the pumped storage system, too.”

“Okay, so tell me how we could make electricity with the tide that comes in and out of Pleasant Bay.”

The tide can be used instead of rivers to make electricity.

Julie looks off at the trees whizzing by along the highway, then turns back to me. “You know that opening where the water flows into the bay from the ocean—out near where the seals live?”

“Sure,” I reply. “That’s how we get out into the ocean with my sailboat.”

“Uh-huh. So suppose we dam up the opening and put a tunnel through the dam, with a door that opens and closes. Inside the tunnel is a turbine. We couldn’t really do all that, but let’s just suppose. Then, when the tide rises in the ocean, we open the tunnel so the water can rush in toward the bay. On the way in, it spins the turbine, making electricity.”

She thinks about the next step, then goes on. “When the tide is completely high and the bay is full of water, we close the tunnel. We wait a few hours until the tide goes out and the level of the ocean outside the dam goes down. Then we reopen the tunnel, and the water pours out of the bay, turning the turbine again as it goes.”

“Wow!” I exclaim loudly, startling the girls in the back. “What a terrific idea! You’re holding back the water as it runs in and out of the bay, and using it to power your electric generator. Very smart!”

Julie looks pleased that she’s been able to describe how a tidal power system works. “Of course, you’d have to figure out a way for boats to get through the dam,” she adds. She knows that I want to take my sailboat out into the ocean. “Gramps, I was reading about locks. Do you know how a lock works?”

 
Video of How a Lock Works

“I do.” How will I explain this to the girls?

“Let’s say it’s low tide in the ocean, but the bay is still full of water. You have two sets of giant swinging doors in the dam, with a short canal in between—maybe a hundred feet long. First, you open the doors on the bay side, and the canal fills up with bay water. I drive my boat past the open gates and into the canal. You close the doors behind me.”

By now Amaya and Natasha are leaning forward so they can hear what we’re talking about. I forge ahead. “Next, you slowly drain the water out of the canal. As the water runs out, my boat floats down to the low-tide level of the ocean. Then you open the second set of gates, on the ocean side, and I’m free to go on my way!”

Natasha hands her iPad over the seat to Julie. “You downloaded pictures of that tidal project over in France, remember? I think one of the pictures shows a lock in the dam there.”

Julie taps the screen a few times. “Here it is,” she reports, turning the screen toward me. “You can see the dam from above, with a road across the top, and the lock.”

I turn on my signal to pull into a rest area. “Let me pull over for a minute, so I can take a good look.” Once the car is stopped, I take the tablet from her.

Using the Tide to Make Electricity

This is a tidal dam in France.

Using the Tide to Make Electricity

A lock is used to let boats pass through the dam.

Using the Tide to Make Electricity

The swirling waters on the left side of the dam have come from the other side and passed through generators below water level.

Using the Tide to Make Electricity

This picture shows the water with the tunnel gates closed and then opened.

Using the Tide to Make Electricity

These are the generators that the tidal water passes through at the base of the tidal dam.

“Whoa, that’s a big dam. Is there lots of tide along the coast of France?”

Julie’s answer comes quickly. “At high tide, the water is twenty-six feet deeper than at low tide. That’s much more change than we have on the Cape, isn’t it, Gramps?”

“It certainly is. We have only about ten feet of difference between high and low tide in the ocean. It’s even less in Pleasant Bay—about four feet.”

As we merge back onto the highway, Natasha picks up that thought. “So, the best places to make electricity with the tides are places where there’s a big difference between high and the low tide. Do you know where those places are, Julie?”

“I found a list of places with the greatest difference between high and low tide,” Julie replies, after doing a Web search. “Here it is. The best tides are on the east coast of Canada, straight north from Boston, and also on the other side of the Atlantic—near England, Scotland, and France. There are also some big tides in Alaska and down in South America.”

I look at Julie with admiration. “You girls have done a great job with your water power project so far,” I say. “I’m very impressed. You’ve taught me a lot.” They all look pleased.

Julie is focused on one more picture on the screen. “One more thing about tides, Gramps,” she says through a yawn. “In some places where there’s lots of tide, people are actually putting machines that look like windmills down in the water. The tide rushes past them so fast that it turns their blades and generates electricity.”

She holds the tablet so I can see it without turning my head. “See, it’s like a windmill, but the blades are turned by water instead of the wind!”

Tidal “Watermills”
The incoming tide turns the blades on these “watermills,” which are attached to turbines like those on wind machines.

 
“That’s amazing!” I sneak a quick peek. “It looks like the windmill behind our house on the Cape, except it’s under water.”

Julie smiles and hands the iPad back to Natasha. By now darkness has fallen, and we’re chasing our headlights down the highway.

As we come over the brow of a hill, a nearly full moon is rising above the valley to our right. The girls greet the sight with excited ooohs, and I hear Julie whisper something that sounds like “Lunar power.”

“What was that you said?” I ask her.

“Lunar power,” she repeats. “The power of the moon. That’s what makes the ocean tides go up and down. So those tidal power plants are turning the power of the moon into electricity.”

“Good thinking, Water Woman,” I say.

“Tom’s been studying solar power and I’ve been studying lunar power. I love the moon!”

“I do too,” Amaya murmurs sleepily from the back seat.

“Me too,” agrees Natasha. She snuggles into the pillow she brought along just for this purpose. For the rest of the return trip, I’m left to my thoughts about how best to use the energy from the sun, wind, and water.