Posted on 06/30/2018 12:09:17 PM PDT by 2ndDivisionVet
Bingo.
I hope I didn't offend you, Zerobama. If I did, I don't care, since you are offending my PRESIDENT!!
I'd refer to it as "instantaneous standby capacity", like the bypass capacitors on my circuit boards.
Yes, in an abstract sense you're right, but of course bypass capacitors store picojoules or nanojoules of energy, whereas spinning reserve has to be able to supply hundreds of kW in one or two revolutions of the alternator shaft; also bypass caps are acting to (try to) hold a DC bus at a constant voltage, whereas utility spinning reserve is trying to hold an AC bus at a constant frequency.
There are disturbances on the order of microseconds (lightning strikes and squirrels shorting out phases) of course, but those are taken care of by other means.
On the power grid's "infinite bus," an alternator that falls behind due to RPM drop becomes a motor, sucking energy from the grid. Thus the problem becomes one of phase control, really. Each alternator is a synchronous device that must be phase locked to within a very small amount (like a fraction of an electrical degree) of the grid at large.
If there's a sudden load change, at least two things happen fast: one is that the exciter current of the alternator is bumped up to supply enough field to keep the alternator's output voltage high enough so that it is a net source to the grid. The other is that (as I said before) more energy is supplied to the prime mover to keep the drive shaft in phase with the other devices on the grid. That happens a little more slowly because the amount of mechanical energy stored in the spinning turbine-alternator rotor assembly is hundreds of millions of joules, and inertia will carry the device for a few revolutions.
I forgot to complete my thought before. The problem with wind power is that — well — it varies with the breeze. Since the utility's customer's demands do not vary with the breeze, the utility has to supply spinning reserves to back up any wind turbines that are on the grid; the amount (I was told) they plan for is 75%, meaning each kW of wind turbine has to have 0.75 kW of spinning reserve somewhere, ready to take over if the wind dies off.
This of course costs the utility money, and that amount of money subtracts from the economic efficiency of wind turbines. The same is true of photovoltaics; if a cloud obscures the sun, and your PV installation suddenly drops from supplying 50 MW to 5MW, that's like someone just fired off an electric arc furnace on your grid with zero warning.
> Thanks for the info on photo voltaic, I was about to plop down a lot to install solar panels on my home in S Florida.
In Florida they might pay off, since you use electricity for cooling; the point I was trying to make (and I didn’t do too well) is that the cheaper the cells, generally speaking, the better. The price of the tech will decline further, and efficiency of the cells has risen.
> Use will promote efficiency, right along with battery technology.
Efficiency of the cells won’t improve much — the area of improvement will be the cost of manufacture. When (if) a breakthrough is made in ambient temperature superconductors, replacement of the trunk lines with the new material(s?) will in effect approximately triple electrical production in the US without building a single generating plant. Changing from direct use of fuels to buried heat exchangers (a heat pump system; some neighbors have used that for over 30 years, the price of those has risen, alas) would be an understandable consequence to the net reduction of generating costs.
btw there are no trees near my house though I have several tree in front and in the backyards. Plus the length of the house runs East to West and faces to the south.
The reason Elon Musk's company sells those battery storage subsystems is that our wonderful Sun, which has a lot of really positive qualities, doesn't stay in the sky 24/7. Without tracking, cells are at a fixed angle, and have a "sweet spot" centered (usually) around midday. The angle of the Sun also varies due to the time of year. OTOH, your situation sounds pretty close to ideal. The question is, always, whether your current monthly cost of electricity doesn't exceed the amortized cost of your solar installation -- and of course, your monthly cost of electricity will rise slightly over time. Electricity happens to be a gi-normous bargain, even with the various criminal enterprises enacted by the Demwits in order to enrich Al Gore et al.
Yeah, well under ideal conditions the electric bill is near about $150/month. And I almost forgot to mention that I was also planning to add a Power Wall UPS bank (13kWh) for starters though this is the most expensive add-on at $6,600 for the hardware alone.
We're starting to see a shift to high voltage DC (HVDC), with that being a big factor in favor of the switch
Thanks for the link. Very interesting.
Wow, that's a nice big electric bill. I finally couldn't sleep last night, shut the windows, and kicked on the air. It was still dark of course, but the whole-house system ran until I fell asleep and was running when I got up for the first pee break. It was pushing 100°F all day, and with the strong wind, I felt like an entree in a convection oven. ;^) I turned the thermo up to 80, and it has since cooled down outdoors. With the windows and doors closed, I don't think it will run much, and plan to shut it off tomorrow.
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