The first thing you notice about a coal-fired electrical plant is the noise. I felt like I was inside the engine of a jet plane. And that was while I was wearing earplugs.
The second thing you notice is the heat. The boilers burn coal at 2,600 degrees Fahrenheit.
"It's a big fiery tornado in there," shouted Darren Kearney, an environmental analyst for Xcel Energy, as he pointed to the boiler during a tour of the Allen S. King plant. Call me geeky, but this is what my family did for entertainment a couple of weeks ago. It was a beautiful fall day, and I took my son and stepfather to see how electricity is made.
The process is straightforward. Coal is burned to boil water. Super-hot steam shoots through pipes at high pressure and turns the blades on a giant turbine, which turns the rotor of the electric generator. The fun is seeing it in action.
Most Xcel power plants offer free tours to anyone age 10 and older, though they cannot always accommodate very small groups. I picked the King plant just south of Oak Park Heights in part because I wanted to see new pollution-control equipment that had been installed in the past few years.
The King plant had been the third-worst polluter in the state, and now is among the cleanest coal plants in the nation. Since the new equipment was installed, sulfur dioxide and nitrogen oxides emissions have dropped 90 percent.
"I started here in 1979, and we always saw something come out of the stack," said plant manager Tom Smith as he gave us a short presentation before the tour. "Today, if I'm driving to work and see something come out of the stack, I know something is wrong."
My 11-year-old son was bored with phrases like "nox" and "electrostatic precipitator." But he perked up when we put on hard hats and headed into the powerhouse. We climbed metal stairs past huge tubes and the throbbing cyclone boiler to the 11th floor.
Kearney pointed out braces that suspend the giant boiler from the ceiling. The boiler expands and contracts up to 18 inches with temperature changes and would crack if it sat on the floor and had to bear its own weight.
Next, we walked onto the plant's gravel roof, where we had a sweeping view of the St. Croix River and giant heaps of coal that look like black sand dunes. The plant used to burn coal from Illinois, and you can still see a tower on the riverbank where it was unloaded from barges. Now, trains haul in Wyoming coal, which has lower sulfur content and emits less sulfur dioxide.
"We go through three rail cars every hour," said Kearney, gesturing toward a string of rail cars on the track below. "We get a new train every day or two."
The problem with burning coal is it produces tons of harmful vapors. As part of a plan called Metro Emissions Reduction Project, Xcel recently converted two coal-fired plants to natural gas: the High Bridge plant and the Riverside one in Minneapolis.
The utility also spent more than $400 million to increase efficiency at King and install equipment to remove several pollutants from the boiler gas before it blows out the 785-foot smokestack.
From the roof, Kearney pointed out the selective catalytic reduction unit, a large building where vaporized ammonia is sprayed into the gas coming out of the boiler. The ammonia reacts with nitrogen oxides to create nitrogen gas and water. Kearney also pointed out the dry scrubber where a limestone slurry pulls out most of the sulfur dioxide. Inside the bag house, thousands of huge fabric bags filter out particles of pollution.
The plant also will start taking out mercury before the end of the year. However, none of the equipment tackles carbon dioxide, one of the main contributors to climate change.
We also got to see the control room, where four employees monitored all the systems on oversized computer screens.
"It looks like a video game," said my son.
And we walked by the turbine and the generator, which are huge but largely uninteresting, since the moving parts are enclosed. I was more interested in the explanation of what happens to the steam.
Electricity-generating plants are nearly always on a river. Ever wonder why? Cool water from the St. Croix is pumped
We ended the tour in a room where a few employees on break were playing Wii bowling as a United Way fundraiser. And now I have to be completely honest: My son was much more interested in the Wii game than he was in the plant tour. I found the behind-the-scenes peek at electricity generation fascinating, and I know my stepfather, a retired engineer, thoroughly enjoyed himself. But the technical lingo went above my son's head.
Even so, I think the tour was worthwhile, if not entertaining, for my older son. We should all have a basic understanding of what makes our everyday life possible. Now, at least he'll have an inkling of what's involved when he flips the switch to turn on the light in his bedroom.
Maja Beckstrom can be reached at 651-228-5295.
What: Touring Xcel Energy's Allen S. King plant
Where: Oak Park Heights
Information: 651-714-6373 or xcelenergy.com
Hours: By appointment
Target audience: Kids ages 10 and older
Crowd pleaser: Climbing catwalks around the 11-story boiler
Avoid: Hearing loss. Wear your earplugs.
Tip: Before you go on your tour, watch a virtual online tour of an Xcel Energy coal plant at energyclassroom.com.
More: Read previously published Family Outings under "family fun" at MinnMoms.com.
Most of us have no idea what happens to our trash, how we get our electricity or where the water goes when it flows down the drain. Here are a few free public tours to give you a glimpse of what makes your daily life possible. In general, you need to make reservations several weeks in advance. While some facilities cannot accommodate very small groups, most will arrange for you to join a larger tour.
— Maja Beckstrom