TransAlta is Sometimes Off

Do we really need coal power for a "stable" grid?
This post is part of the research project: The Dirt on Coal

Every once in a while, I catch wind of a curious defense of the TransAlta coal-fired power plant in Centralia, WA:  that without a big coal plant smack between Seattle and Portland, the Northwest’s electricity grid could somehow become “unstable.” 

To be clear, this is NOT a claim that the region will run out of power if the Centralia plant shuts down.  That’s an entirely separate (and arguably false) claim.  Instead, this is a deeply technical argument about electricity infrastructure: namely, that the region’s power grid was constructed and tested by engineers who assumed that the massive coal-fired power plant at Centralia would always be there.  Shutter that plant, and the complex transmission system might go subtly out of whack, raising the chances of a region-wide power outage.

To me, this sounds…well…awfully convenient for TransAlta, which is trying to extend the life of its carbon-belching, tax-subsidized monstrosity.  But at the same time, power grids are just wacky enough that it could be true.  After all, the Northeast blackout of 2003 was caused by a cascade of minor glitches, none of which seemed catastrophic on its own, but which ultimately left 55 million people without power.  So maybe, just maybe, shutting down Centralia could amp up the risk that small power-supply glitches could escalate into a catastrophic meltdown of the Northwest’s grid.

I’m not a power engineer, so I can’t really debate the merits here.  But I did play around with the numbers a bit.  Take a look at the chart below, which shows hourly power output from Centralia’s coal-fired generators from 2006 through 2009.  (Click the chart to see a bigger version.)

TransAlta is sometimes off

The bottom line is this:  Centralia already shuts down for months at a time.  Both boilers were shut down for 84 consecutive days in 2006, and for 75 consecutive days last year.  Each of the last three shutdowns occurred in late spring and early summer, when hydropower was peaking—meaning that the grid was well supplied with power.  But none of that power was actually coming from Centralia’s coal-fired burners.

So periodically, TransAlta withholds the magic grid-stabilization juju that its Centralia coal plant allegedly provides.  I haven’t noticed any mysterious power outages, have you?

Snark aside, there are some serious implications here. 

First, if Centralia’s coal-fired power plant is really so important for keeping the grid stable, then the chart above suggests that we need to fix the grid so that it’s no longer reliant on Centralia.  It’s not that we’ve got to keep the Centralia plant around, but rather that we need to move as quickly as possible to make Centralia irrelevant to grid stability.  Otherwise, the entire region’s power system is being held hostage to a Canadian multinational that from time to time decides to turn off a key stabilizing component. I mean, if a multinational corporation decided to disable the emergency brakes on my car every so often, then I’d sure as heck try to install new brakes! 

Second, it’s really not clear how important Centralia is for grid stability at all!  I’ll leave aside the obvious point that in the very recent past, the grid functioned just fine when Centralia was turned off. Perhaps we were just lucky, or perhaps hydropower—which tends to be running hot when coal is turned off—stabilizes the grid in a way that the abundant gas-fired power in the Seattle-to-Portland corridor simply can’t.  But if Centralia really were critical to grid stability, then you’d think that power engineers would be sounding the alarm every time both boilers were shut down, and that grid operators would be arguing for infrastructure upgrades to deal with the “the Centralia problem”.  Instead, the “grid stability” argument only seems to rear its head when someone points out the Centralia plant’s massive and probably unnecessary carbon footprint, or questions the various tax subsidies that TransAlta’s lobbyists have inexplicably been able to protect, even in a time of massive state budget woes.

If I were in charge of the asylum, I’d try to figure this grid stability thing out as quickly as possible.  And if I found that stability were really a problem, I’d put people to work trying to upgrade the power grid—the sooner the better.  For the politicians who are trying to figure out Centralia’s future, that might make a nifty dance step, since the jobs created in building and maintaining a smarter, more resilient electricity grid would likely make up for jobs lost in shutting down a coal plant.  (Hint, hint.)

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  1. Clark Williams-Derry says:

    I’ve gotten a little pushback on this post, via email. So let me clear something up. First, I really don’t have any opinion at all about whether Centralia’s coal-fired power plant is vital to grid stability. Maybe it is! Second, I hope that nobody thinks I’m making any factual claim here, other than the undeniable fact that Centralia is periodically turned off. My other arguments are more logical than factual:1. Either Centralia’s coal is important to grid stability, or it’s not.2. If it is, someone should do something about it pronto—since (a) we know that it’s off part of the year, potentially exposing the grid to risk, and (b) we’ve got no guarantee that TransAlta will keep the plant running into the future.3. If on the other hand Centralia is NOT critical to grid stability, then we can cross that off the list of concerns about closing it.4. Figuring out the answer to 1 seems like a high priority, since (a) the argument is at least a minor sticking point in official thinking about Centralia; (b) there doesn’t seem to be any agreed-upon answer among public officials about the importance of Centralia to grid stability; and (c) getting this one wrong, in either direction, would be bad!

  2. eldan says:

    It seems significant that each of these switch-offs was around Q2 of a year – outside of peak heating or air-conditioning demand. Could it simply be that it’s important for grid stability in the middle of winter?

  3. KC Golden says:

    Thanks for poking at this Clark—Too much is taken for granted and too little has been thoroughly analyzed about how that plant’s functions can be replaced or eliminated. Of course we don’t need coal for grid stability, but we may need Westside capacity during winter load peaks (looks like the outages you cite were in low-load seasons).BPA freaked out about this after a big cold snap in late 1990 which precipitated the Puget Sound Electric Reliability Plan —a months-long stakeholder process at the end of which, as I recall, the transmission engineers came in and said, essentially, “don’t worry, we have a black box [capacitors, I think] that will fix it.”….there’s also some funky stuff about transmission paths for returning the Canadian Entitlement that bears on this but I’m not sure if that’s still relevant…..There are lots of other ways to handle this—especially now, when we have more gas capacity on the west side and less super-cold winter weather—but it’s not crazy to think that in a state where most of the juice is on one side of the mountains and most of the load is on the other, the system would have some adjustments to make if it lost 1200 MW of Westside capacity……I’m particularly interested in how you could solve most of this on the demand side. Energy efficiency WRT heating loads automatically peaks when power demand does, and smart grid technology could give us a whole bunch of new, demand-side switches to flip in the utility control rooms….. And balancing the system with demand-side measures and some cleaner new generation will create a LOT more jobs than the plant does…..

  4. Clark Williams-Derry says:

    That seems exactly on point, Eldan. Centralia coal is off when hydropower is abundant. So that could mean:1) you need either abundant hydropower or coal at Centralia to make the grid work—nothing else will do!2) the grid is pretty stable as long as there’s enough power to go around—in which case, the newly abundant gas generators in the Seattle-to-Portland corridor can stabilize the grid when Centralia is off, just the way hydropower does when Centralia is off.There are probably other possibilities here too. Regardless, either Centralia’s role in stabilizing the grid is real, or it’s not. If it is, then we should fix the grid so that Centralia’s not an energy security vulnerability anymore. If it’s not, we can safely turn off Centralia as long as we’ve got other reliable sources of power. Either way, we should figure out for sure what’s going on & act accordingly.

  5. Sketchy says:

    I am a power engineer. Stability is driven by 2 major players. 1. Base load – This is the historical amount of power we use on every given day. We need more power in the middle of the afternoon and around 5 o’clock when people are eating/cooking/doing their laundry. We need less of it in the middle of the night when people are sleeping. This is also true seasonally, as pointed out we need more in the summer (air conditioners, more people at home with TV’s on and vacation) and less in the shoulder season when everyone works and the temperatures are moderate. Coal plants are a base load plant. They cannot be shut off and on throughout the day (it in fact takes them 1+ days to get going) so we gotta run them. Base load is planned for and required. Nuclear is another type of “base load”.2. Dispatchable Load – This is the load that is flicked on in the middle of the day when needs demand is there, and off when it isn’t. The thing about electricity is you ALWAYS have to be making exactly as much as you’re taking out, makes this whole “stability” thing a bit tricky. There is one fact that drives this reality, you cannot store large amounts of power. So we use hydro and smaller gas plants that can withstand being turned off an on to accomplish this function. Hydro is good because if they are off, the reservoir still fill effectively saving the water for another day (storage in its basic sense). Gas is just on and off but depends on prices naturally. So why can’t you use gas or hydro as “baseload”. You can. Except water is also seasonal! Very high in the spring when not a lot of power is consumed (notice this is when Centralia always comes off) and next to none in the fall and winter. You can’t continuously meet base demands with Hydro all year round, unless we start using our power seasonally with the rain :). Sometimes gas is used but the volatility in price means your power bill would change drastically with the price of gas, who wants that to happen if gas prices recover? Coal is cheap, there is lots of it, an there aren’t a lot of other markets that change it’s price and availability. So we use it to produce cheap base load power. Wind power is even worse; when the wind blows we get electricity (so we back off something else) but as soon as the wind dies we have to have reserves ready to turn on to keep the lights on.So what’s the answer? a) You make more gas plants and live with the potential for much higher electricity bills (happy to do this if you are). b) Build other dependable baseload power plants (nuclear, coal with carbon capture, contracted gas {good luck right now}). c) Use a lot less electricty. People like their TV’s and air conditioners though!d) Buy it from somewhere else. This comes at a cost and you run the risk of not controlling you’re own power someday (Look at Arizona and Los Angelas right now). This probably won’t solve the overall problem either, just pushing the CO2 into someone elses backyard.e) Increase the capacity of the grid. The more plants you have, the less dependent you are on any one. This could be distributed generation (small generators all over) of just more gas plants (hydro is tapped out I believe). Centralia produces 10% of Washingtons power so it’s hard to just turn it off. Hope this helps out a bit.

  6. Alan says:

    I love it when the policy experts and the folks with boots on the ground experience running these things each share and there’s lots of room to explore commion ground. Sketchy gives the power primer anyone thinking of this needs to grasp, especially the zero-sum nature of power production and distribution (production must near instaneaously equal consumption, a near miracle of modern life is that it does). KC offers his depth of experience at important tables around which discussions have been held and decisions made over the decades.Here’s a little more fodder:Only in the Northwest does the supply picture include such a big gift and buffer offered by nature (and the Columbia River System’s attempt to control it). The shut down of Centralia in the late spring and early summer is entirely a non-issue and does not point to any fallacy in claims for load and transmission support. We also have probably the only nuclear plant in the hemisphere that shuts down in concert with hydropower supply trends too. Absent thousands of changes large and small, I doubt we could close Columbia Generating Station anytime soon, just because we can do so now and then.The owners of Centralia and Boardman know the coal days at these plants are numbered and await clearer economic and regulartory signals. Portland General Electric is open about its plans to close Boardman early, and Transalta is somewhat less transparent about the likeihood that emmissions targets it is suggesting it can meet imply that it is considering switching to gas, possibly even before Boardman closes in 2020.So the take away is that we are lucky to live where the hydro base can do versatile duty as we get serious about alternatives to fossil energy for power generation.

  7. Paul says:

    System stability is controlled by raising and lowering generator output voltage which either boosts or places a drag on grid voltage depending on what type of loading the grid has on it. Unfortuately, it takes large electrical generators like the ones stationed at Centralia to affect system voltage. Small generators do not have the ability to impact system voltage nearly as much as large generators. Centralia does work with BPA to maintain grid stability.Voltage is like pressure in a garden hose, the more demand the lower the pressure goes and vice versa. Large genarators have a greater ability to affect overall voltage (pressure) compared to smaller generators. As demand increases and system voltage drops, amps increase on all of our sensative electronics, motors, etc. and is seen as heat which can damage or destroy equipment. In times like these, large generators can boost or reduce their output voltage more effectively to reduce the negative impacts caused by system voltage instability.The other advantage to having large generators close to large loads such as Seattle & Portland is the fact there is less line loss. Basicaly, the greater the distance between generation an load, the greater the voltage drop. This is another reason it is realatively important to have large base loaded stations near the load.The hydro base is a blessing but is not always as reliable as we would like. Hydro faces its own issues including seasonability, the reliance on adequate snowpack, and one that most people don’t think about which is fish runs. The fish runs cause the hydro operators to adjust flows at times to accomodate fish as opposed to operating at maximum loads and efficiency. The likelyhood of any additional hydro load is probably next to nil.Gas plants are quick and easy to start and stop depending on system demand but many are subjected to cyclical gas pricing and economics that put them out of the market at times. Gas plants may be somewhat cleaner but are also a significant source of NOx, CO, CO2, etc.Solar and wind are a good addition to the mix but need to be totally backed up by base loaded stations that can provide a spinning reserve to offset their generation whenever the sun isn’t shining or the wind dies. To maintain grid stability, loss of generation from one point has to be replaced by generation from somwhere else in short order. Inadequate spinning reserve can and will lead to grid instability and the potential of blackouts.The greatest negative of solar and wind is probably the shear amount of acreage that will be required in the future to site new generation, probably in the thousands of acres. There will definitely be an environmental impact felt by these sites, affecting wildlife and habitat more than anything else.On a side note, for many years the Mojave coal fired plant was being blamed for air quality degredation in and around the Grand Canyon. The plant was eventually taken out of service, air quality did not improve as expected. Further studies have revealed that the city of Los Angeles was a major contributor to the air quality issues. Basically, until auto emissions, etc. are drastically reduced, many air quality issues will never improve.Centralia has reduced its emissions significantly. By installing scrubbers and burning PRB coal, the plant reduced SO2 emissions from over 900 ppm to less than 15 ppm on avearage. Installation of low NOx burners has drastically decreased NOX emissions. Burning PRB coal which has a higher BTU than native coal also reduced the amount of coal burned to produce the same generation. Centrailia is using some of the latest tecnology to control and reduce emissions further as they become available. Waste products such as gypsum and ash are recycled and being used in the construction industry.Several posters noted that the plant shuts down during high hydro runoff season. The plant has been blamed many times for visibility issues at Mt. Ranier. I have personally seen times when the plant has been down for months and Mt. Ranier is barely visible. It is my contention that the larger culprit in this matter is the auto traffic on the I-5 corridor and Seattle – Tacoma metro area, having a larger impact on air quality and visibility. Centrailia may be a large single source of certain emissions but may pale in comparrison to the cumulative totals from other sources such as autos, etc.Loss of the Centralia facilty will have a huge economic impact on the local economy, both in lost tax revenue and living wage jobs. The local economy of Lewis County is already facing one of the highest unemployment rates in the state of Washington. Closure of the Centralia plant will be like closing Boeing or Microsoft in Seattle. The Centrailia plant issue is multi faceted. America is considered to be the Saudi Arabia of coal, we should always have coal in our energy mix to insure the security of our country. We need to find ways to reduce the negatieve impacts of using fossil fuels while at the same time reducing our dependance on foreign sources. Thanks for your time.

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