Fair warning, this post is going to be mostly anecdotal.
I just got back from spring break, and during my time of vacation I saw a few old friends and met a lot of new people. Inevitably, I ended up talking about nuclear power and engineering as "what do you do for a living" came up in conversation. Most of the people I spoke with were well educated, but one of many common points of conversation struck me: no one really knew where nuclear power fell in their power grid.
As a general rule, a nuclear reactor doesn't like to change the power level its operating at. It's not like the engine in your car, that you can change dynamically with the press or release of the gas pedal; yes the reactor can be adjusted across a range of outputs, but it's a relatively slow process. Fortunately, there's a place for that kind of power source in the power grid: covering the "base load".
In a given region, the local utility provider(s) will spend a lot of time determining what the minimum draw on the grid will be. For example, in a Florida summer you expect the average household to be running its AC unit, and you expect that unit (which, as household appliances go, is pretty inefficient and a rather large draw of electricity) to draw a certain amount of relatively-constant power. The combination of all of these AC units create the "base load", a minimum amount of power required to keep the grid operational without brown outs or worse. This can be provided quite effectively by a nuclear power plant, which doesn't want to change its power level much, and certainly doesn't want to shut down as may be required in an oil or natural gas power plant (which can change their power levels dynamically, and are used to cover the rises and falls of power during the day, from people's lights, televisions, etc.).
Unfortunately, the characteristics that make a nuclear plant good for the base load are almost all applicable to coal power plants as well, making the two direct competitors in the power market. Both have their advantages and disadvantages, and I hope to do a more factual and detailed comparison between the two later this week.
So if you live on a grid with nuclear a nuclear reactor, chances are you have nuclear power to thank for your AC or electric heater, and hopefully it's making it cheaper as well.
It's interesting that your smart friends don't know about nuclear power. I guess it's easy to forget that most people don't really think about it, especially when your entire course load is about nuclear engineering...
ReplyDeleteYeah, it's hard to remember what all is going on in other engineering majors, and we're about closest to knowing them. Imagine looking from the outside in, especially back as freshmen and while we were Nuclear Engineers taking Chem 1 and Calc 2, our parents and friends were in awe of what we did and kept asking nuclear questions. That was back when I didn't know anything about the major (not that I really do now!).
DeleteMIchael, I totally agree. Even as a freshman choosing nuclear engineering, I didn't know much. I think part of the problem with the perception of nuclear might be that people don't know how much it contributes to their daily life. Additionally, utilities don't usually market their nuclear energy because they're afraid their customers might not like it. We need to find a good way of getting this information out to the public.
DeleteOne of my friends has even done research in theoretical plasma physics, and I had to explain to him that their are different kinds of radiation! Apparently he'd only ever had to deal with considerations for gamma and x-ray release, and the electrons lost when the gases were ionized to become plasma, they were simply ignored.
DeleteAnd Michael: it's been especially fun living with other engineers (one chemical and one mechanical) these last few years. We all started out dragging ourselves through the same weed-out courses, but as upperclassmen our fields (slowly at first, then very quickly) diverged. The term "engineer" is so broad these days--it applies to all three of us, but each of us could talk for hours on subjects in our field the other two have zero knowledge of.
DeleteBecause nuclear plants cannot ramp up quickly, wouldnt there be a need for smaller gas powered plants in the event of a large load coming onto the grid at one time? Or does this not happen?
ReplyDeleteBeyond the expected minimum baseline, the power requirement on the system is pretty much constantly fluctuating, sometimes to drastic degrees. Though it tends to follow trends (usually based around time of day) it can still be a little random. Gas or oil plants, which can vary their temperature and subsequent power output much more readily, are "load following", they automatically change their output to match the needs of the grid.
DeleteThis is of course an imperfect system, and when those drastic increases or decreases happen at a rate too fast for the plants to follow you get brown outs and power surges.
There is the possibility of eventually building more reactors being the SMR type which would allow for more variance in power levels.
ReplyDeleteAs far as I know, SMR designs are still for base load providing but for more remote areas that would have smaller energy needs. The idea for SMR is that a smaller plant is easier to build. Thus new reactors can be built to account for an increase in need in the area.
DeleteIt's not the ability to build reactors of different power levels that's the problem, but the fact that a reactor is built to operate at a certain power level, and this power level isn't varied easily. As we've seen in the test reactor in lab, the power level of the reactor changes slowly, and it's especially slow compared to the more-or-less "turn a knob" functionality of a natural gas reactor.
DeleteI didn't know that coal plants operated base-load, always assumed they were load-follow like natural gas. What's the difference? Does it take longer to get to temperature?
ReplyDeleteA friend of mine worked an internship at a coal plant a couple summers ago, and told me that the boiler in their plant takes an incredibly long time to reach optimum running temperature. Coal isn't as combustible as natural gas, the fire has to be started then stoked until burning at full capacity (and then more fuel constantly added). If I recall correctly, he said going from a completely cold boiler to running temp took about 16 hours for their plant, and some larger plants are known to take as long as two days.
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