Powerplant Tours – coal and solar

Over the past several weeks, we’ve had the opportunity to visit two very different commercial power plants.

First was the gigantic 2.4 GW Belews Creek steam plant. We often see (and hear) the train carrying coal to the plant, and the two giant exhaust stacks with their plumes of steam are visible from any high spot in the surrounding counties. (They are a main feature we can see from the top of Moore’s Wall in Hanging Rock State Park).

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The tour was organized by the local chapter of ASME, and even though we’re not currently members, we were able to participate in the tour.  Given the size of the facility (this is a multi-billion dollar project with nuke plant size capacity to make power), I shouldn’t have been surprised at the high quality of the tour. The plant is owned by Duke Energy, and giving tours of the plant was clearly part of our tour guides’ job description (although it was far from his main responsibility). We sat through an excellent power-point presentation, and then were led through various parts of the facility.

From the roof, we were able to see where the coal arrives by train, and then follow the process (and endless conveyors) that reduce the coal to a fine powder for supply to the boiler. The roof also allowed us to see the intake from, and exit to, the lake used for the cooling loop. Inside, the boiler is impressive on its own; its impossible to see the entire 14 story (or so, we didn’t get an actual measurement) structure at once. Although considered a plant with two identical units, there are actually four turbines and generators, a low and high pressure on each side.

The control room was probably my favorite part.  If the Star Trek Enterprise spaceship was powered by coal, it would look like this. Employees train for a year to be eligible to sit in one of the two seats surrounded by a wall of flat panel monitors, dials, and switches. Training is done a a control system simulator that lets the trainer simulate various problems that the trainee has to solve. Kevin and I did not have nearly enough time to talk to those guys.

I was pretty surprised to learn that it takes at least eight hours and over $300,000 to start a unit after its been offline, and that synchronizing that enormous 2.1 GW unit is done by hand, via a guy in the control room closing the switch. Oh, and synch-ing to the grid isn’t done until the unit is making over 40 MW of power. (To a small hydro person, these numbers are pretty mind blowing).

I have to say, given the current debates about where we get our energy in this country, and my personal disdain for digging rocks out of the ground and burning them, I still found this plant to be pretty amazing. I would recommend that all coal critics (I’m not really one, btw) visit a plant, if only to really understand the problem, but I’m pretty sure not all coal plants are like this one. Belews creek is about as modern and clean as it gets with coal. The thermal efficiency achieved consistently makes this plant one of the top ranked (if not first) in the country, and the mind-boggling amount of money spent to reduce harmful emissions must only make sense at the largest scales.

Sorry, no pictures allowed inside the plant. Thus the single picture of the stacks at the top of the post.  You’ll just have to go on your own tour.

The second plant we’ve visited recently is on the complete opposite end of the spectrum. Through a local renewable energy group, we were able to visit a brand new solar farm in rural NC.

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The contrast the coal plant is pretty stark. The solar plant is 5MW (which I think is still fairly large for solar), and is placed on about 40 acres of pasture rented from the neighboring chicken farmer.

I’m rooting for solar to become a larger part of the energy mix, but right now the business model still seems pretty heavily dependent on subsidies. This particular farm is built and run by a company that has what I think is an excellent strategy. They’re building identical 5MW plants all over the place in NC. The cookie-cutter approach saves a huge amount of money. The price of the solar panels themselves has fallen exponentially over the last few years, making commercial farms more and more attractive. Plus, this company doesn’t bother with expensive solar tracking adjustable panels. Their panels are fixed, sacrificing some efficiency, but dramatically reducing cost and upkeep. However, the price per installed watt is still to high, and the price for the balance of plant components are still a bit prohibitive. The price for the inverters, for example, is still almost as much as the panels.

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The complexity of the plant is also a stark contrast. The solar farm is so simple. It just sits there. It doesn’t even need a control system, there’s almost nothing to control, or even monitor. It only takes a year from the decision to build the plant to have it up and running, and construction takes an average of about 90 days. Plus, if you want to take the plant out after 20 years, its pretty simple. They did almost no permanent modification to the pasture; there was very little grading. They basically did some clearing, mowed, and leveled the spots needed for the concrete pads for the inverters and transformers. The panels are mounted on framework that can be removed from the ground fairly easily with the right equipment. Its not far fetched to see how that farm could be turned back into a pasture that would leave very little evidence it ever existed.

I don’t believe that solar is ever really going to be the major source of energy in this country. Without storage, its just too intermittent to be baseload power. (Maybe we’ll be able to solve this, I don’t know). However, I do think solar will be (or already is) cheap enough to offset power at the residential level. I hope to put solar panels on my next house, and if the price falls just a bit more, I bet a lot of other people (in sunny states) will too.

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