A couple of days ago, we lost power for a few hours in the the aftermath of hurricane Debby, as it moved up the coast. I took a walk during a break in the rain and found that a tree had split, bringing down some power lines a couple of blocks from my house.
Here are a few observations, sitting on my back porch, waiting for the power to come back on.
1: It’s noisy around here when the power goes out.
Source: Electricgeneratorsdirect.com
Used to be, power outages brought some quiet to the ‘burbs. If nothing else, in the summer, all the AC compressors shut off.
But now, I can barely hear the wind in the trees over the droning of home emergency power generators in my neighborhood. Instead of a bit of idyllic quiet, it suddenly sounds like I’m in the middle of a busy construction site.
All it lacks are the back-up beeps.
Unsurprisingly, these are all attached to the gi-normous McMansions that have sprung up in my neighborhood over the past decade. (See my prior posts on the “tear-down boom” in Vienna VA.) I’m guessing that about one-in-three of these new houses came with a permanently-installed natural-gas-fired generator.
The instant the power goes out, instead of quiet, you hear generators kicking in all over the neighborhood. I can hear at least three, from my back porch. Those turn on automatically, and won’t shut down until the power comes back on. No chance they’ll run out of fuel, because these are connected to the natural gas supply.
It’s not as if my neighbors suddenly had some sort of preparedness mania. They didn’t rush out and buy big home emergency generators in anticipation of the next snowpocalypse. It’s that if you’re going to pay $2 mil for a house with all the extras (home theater room, sunken walk-in closets with windows, wine room, and so on), the $10K cost of an installed generator is rounding error.
So this is how power outages will sound in my neighborhood, for the rest of my life. And as more small houses are torn down and replaced by as-large-as-the-law-allows McMansions, the density of emergency generating units is only going to go up from here.
2: What is the sound of one reefer idling?
Now we get to the truly annoying part.
Near as I can tell, these new-fangled generators all seem to be old-school direct-drive units. That is, an internal combustion engine (burning natural gas, in this case) is directly coupled to a generator creating alternating current (AC).
With that setup, the speed of the gas engine determines the Hertz (frequency) of the AC voltage. The gas engine must therefore run at constant high speed to maintain 60 Hertz (cycles-per-second) AC. That’s achieved by a governor that tightly regulates the speed of the engine. At low electrical load, the engine runs just as fast and as loud as at high load, it just strains less to keep the generator spinning.
To a close approximation, these things are every bit as loud at idle — with no significant electrical load — as when they are putting out their maximum rated load.
The upshot is that each one is about as loud as a refrigerated truck.
So, instead of a bit of quiet, a power outage now means that my neighborhood sounds like a bunch of big diesel trucks are parked here,running at high idle.
3: Where was I? Ah yes, thrum-thrum-thrum. Quiet emergency generators, explained.
So, as I sit on my back porch, enjoying the breeze and listening to the throb of my neighbor’s emergency generators,I figure I should explain the concept of “quiet” inverter-generators.
With an inverter-generator, the gas (or natural gas) engine turns a generator that generates DC electricity, which feeds a piece of power electronics called an inverter, which then electronically generates the required 120 volt 60 hertz AC.
For that style of generator, there is no link between the speed of the gas engine and the frequency of the resulting AC (house) voltage. This means that under light load, the internal combustion engine can slow down, and for any power demand, can be run at the speed/torque combination that most efficiently produces the required power output.
So inverter-generators are both more efficient, and on average quieter, than old-school direct-driver generators. Though you will hear the engine speed change if there is a material change in the electrical load placed on the inverter.
Old-style direct-drive generator units are simpler to make than inverter-style generators. But they are inherently less efficient, and, it seems, intrinsically louder, on average. In any case, modern inverter-style generators have taken over the small-portable-generator market, specifically because they can be marketed as “quiet” generators.
4: Direct-drive generators, inverter-generators, and three-legged-dog generators.
But my neighbor across the street, and one house up, seems to have purchased the worst possible kind of emergency generator. It’s a maintenance-free natural gas generator that nevertheless runs like a three-legged dog.
The engine on that has kind of a ragged one-cylinder miss. Which means that the engine speed and sound are constantly changing. Which means the noise doesn’t fade into the background, but is constantly noticeable. Particularly if you know anything about how an internal combustion engine is supposed to sound.
The result is an impossible-to-ignore loud thrumming noise, originating about 50 yards away.
Worse, while it sounds like it has a fouled spark plug, if I listed closely, a) the miss is a little bit too regular, and b) it seems to stop briefly from time to time. I’m guessing this may be how the engine is supposed to run, and that it purposefully shuts down a cylinder under low load. (I recall that GM tried such a strategy with some V8s, where fuel flow to half the cylinders could be cut off (e.g., when cruising at speed on the highway, where horsepower demand is low.)
So I think that not only am I being treated to the relentless thrumming of this generator for this outage. I think that’s actually the way the thing is supposed to run. So that I will be treated to this delightful noise every time the power goes out, from here on in.
I guess if I don’t like it, I can just hole up inside.
I may be without power for a while.
Maybe I need a my own whole-house generator. That way, I can sit inside, in the AC, during a power outage, like all my neighbors.
4: Quieter emergency power? Hybrid-or-EV-plus-inverter, and USB-tethered Wifi hotspot.
For my emergency power source, I keep a 1 KW inverter on the shelf of my garage. Hook that up to the 12V battery of a Prius, turn the car on and leave it, and run a heavy-duty extension cord from car to house. The car will start and run the gas engine occasionally, to keep the battery up. The only sound it makes is the occasional few-minute stretch with the Prius idling.
If the power isn’t back on in a couple of hours, I can set that up so that up so I can run the fridge. In the meantime, I got around the loss of my FIOS internet by attaching my phone to my laptop, and using my phone as a Wifi hotspot.
5: Aside: Of magnetos and bike speedos.
Source: Amazon.
Weirdly enough, I just installed a generator of sorts the day before this storm.
Old-school direct-driver backup generators are alternators. That is, they directly convert mechanical motion into alternating current.
New-style inverter-generators are generators. That is, they convert mechanical motion into direct current. Which is then converted to alternating current by an inverter. (Well, technically, a generator is anything that generates electricity, AC or DC. But if it generates DC, you have to call it a generator, not an alternator.)
And then there are magnetos, something most have only heard about in the context of piston-engine-driven aircraft. A magneto generates pulses of electricity used to fire the spark plugs of the engine. It does this by passing a rotating magnet near a densely-wound coil of wire. A common example is a typical gas lawn mower, where a magnet embedded in the flywheel creates the spark for the spark plug is it whips past a coil mounted a hair’s-breadth away from the flywheel.
And, oddly enough, an old-fashioned wired bike speedometer uses a magnet on the spokes, and a coil of wire on the front fork, to generate pulses of electricity in time with the turning of the wheel, which it then translates to speed. Not exactly a magneto, but definitely in the magneto family tree somewhere.
6: Final aside: Just say no to GPS
Finally, apropos of nothing, bike speedometers are yet another area where the tech changed when I wasn’t looking. And, in so doing, converted bike speedometers to just another class of disposable electronic devices.
Old-school wired bike speedometers work as described above. They are, in effect, little magnetos, counting the rate at which a magnet on your spokes creates a tiny little electrical signal as it passes a fixed coil of wire. In addition to wired bike speedometers, there are old-school wireless ones where the magneto signal is sent via radio waves. Near as I can tell, these have all the drawbacks of wired ones, and none of the advantages.
But, because these are both old technologies, typical units come with easily-replaced standard button-cell batteries. Buy a good one — I am partial to the Sigma brand — and they’ll last for decades. Just change the battery every few years.
And then there’s GPS bike speedometers. The latest thing.
In theory, this is a step up from magneto-based bike speedos, because there’s no need for any cables. The speedometer captures a GPS signal, so it knows your location, and can infer your speed. All for about the same $30 cost as a name-brand wired bike speedometer.
OTOH, owning one of those means that your bicycle now makes a permanent, downloadable record of exactly where you rode your bike, and when. Presumably, this appeals to people who don’t mind all the involuntary electronic surveillance we already undergo.
But I simply didn’t want to buy yet another device that tracks me. So, despite the ease of installation (no cables), I took a pass on a GPS-based bike speedometer.
If you immediately got to that punchline as soon as you saw “GPS”, then you get an A.
But, in addition, if you also inferred that these all inexpensive GPS-based bike speedometers have non-replaceable batteries, change that to an A+
And so, as with so much modern small electronics, these devices are disposables. They come with an embedded USB-rechargeable lithium-ion battery. When (not if) the battery reaches the end of its life, your sole option is to chuck your old one in the trash, and buy a new one.
Worse, there is clearly no engineering reason for this. The previous generation of bike speedometers all had replaceable batteries.
It’s just that times changed. User-replaceable batteries on cheap electronics had already become a thing of the past by the time low-cost bike GPS speedometers came on the market. And so, if you want a cheap GPS-based bike speedometer, your sole option is to buy a disposable one. Though, of course, none of them are labeled that way.
Which is how I ended up installing a little magneto-based wired bike computer on my wife’s bike. It keeps no record of where I’ve biked. And when the battery wears out, I can replace it.
Conclusion
When one house in a neighborhood has an automatic backup power generator, that’s an oddity.
When every third house has one, it’s cacophony. As soon as the power goes out, the neighborhood is full of the sound of many loud, small, internal combustion engines, each powering an old-school direct-drive alternator.
I hadn’t realized how bad it had gotten in my neighborhood until I tried catching some breezes on my back porch, during this most recent power outage. A power outage now makes my neighborhood sound like an overnight truck-stop parking area.
With any luck, maybe this is just a phase these houses are going through. These days, you can buy a power wall or similar large home storage battery, which then serves as your backup power source. So that maybe the next wave of oversized McMansions will come with quiet emergency power.
But for now, as small older houses in my area are steadily torn down and replaced by McMansions — where the built-in emergency generator seems to be a popular option at the moment — it’s only going to get louder.
