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I've been reading "Living On the Grid",… a basic introduction to how power grids work. I knew very little about the topic, so while it's not electrifying reading, it is enlightening. A bit of what I've learned, mostly new to me:

-The main point of having a power grid is reliability. In return for the enormous complexity of tying together multiple power plants, you can mostly eliminate blackouts and other poor service. Our dependence on "the cold chain" for food makes this steady supply more than a luxury.
-A power grid acts as a single pool of electricity with providers dumping energy into the system, so that it's sometimes hard to distinguish who's contributing what.
-There are three grids covering most of North America: the eastern, the smaller western, and Texas's own network. (This is a deliberate choice by Texas to evade some federal control, and one reason why Texas could become a free country.)
-The grid generally doesn't store power. This is a huge problem because managers must constantly try to balance the output of the power plants with demand, which is constantly changing. It's possible to predict demand somewhat based on daily and yearly cycles, but plant managers sometimes end up praying for an afternoon thunderstorm to cool the area off so that people will turn their A/C off. There are some technologies for storing power already, but what might really make the concept practical is... millions of electric cars whose batteries are hooked up to the grid, available to charge and discharge for non-automotive purposes.
-There are tricks that customers barely notice to balance load and generation. Besides various levels of public notices saying "please don't run all your appliances at noon on a hot day, damn it", power companies can let the alternating current frequency (60 Hz in North America) slip slightly, which saves energy, and ramp power plants up and down.
-There are countless contracts constantly happening to buy and sell power across various regions. As technology has advanced there's been somewhat of a move toward a free market with ever-more-complex transactions, but some players have been kind of clueless about points like thinking they can buy power and "store it on the grid" somehow. One big change is that generation is now mostly marketed separately from transmission (getting it to the customer). One thing that hasn't changed is that the whole system is regulated to hell and back. The author comments on the California "deregulation" experiment as having had regulations that doomed it.
-The grid is built to handle a "single contingency", meaning any one major equipment failure at a time. The operators constantly run simulations of the next hour or day to be ready for anything, and something somewhere breaks almost daily. As a result, there needs to be extra production and transmission capacity, built years in advance of it being directly needed. Often a power company will buy this extra capacity for a few years to hold off on upgrading their own equipment.
-Because there's a need to balance supply and demand in real time, it's necessary to bring power plants online and offline, or dial their output up and down. This process is very complicated. Power plants often have minimum output levels, and can take hours or days to start from a dead stop. Some also need considerable energy to get started, which means recovering from a total blackout is especially hard. ("Lucifer's Hammer" alludes to this problem by mentioning that having one power plant running would help rebuild civilization.)
-Renewable energy can be a problem for the grid. One reason is that they're unreliable. If you're obsessing over perfectly matching two numbers, you don't want one of them to be fluctuating with every passing cloud. (The author cites Europe's experience with wind power, saying that spreading windfarms over a large area helps even out the chaos.) Second, owners of renewable sources hate being told to throttle down their output, because that means throwing away "free fuel" compared to, say, telling a coal plant to just shovel less coal into the furnace. Nuclear (fission) power is like renewables in that the fuel is shedding energy constantly no matter what, so taking <100% output is a waste. As we put more "green" energy online, these problems will tend to get worse. There's also the matter of political uncertainty. Rightly or not, there are proposals to severely tax or subsidize some types of power, and the uncertainty of who gets elected is going to have big effects on the profitability of each type. It's tough to invest in new power plants if you don't know whether the next president or prime minister will have it in for your industry. Even leaving the politics aside, we don't know for instance what the future price of natural gas will be, so market factors make the ideal power mix even less certain.
-Because having spare capacity available is important and some plants have a minimum output, it sometimes happens that a specific power plant is usually offline or barely running. Yet "they also serve who stand and wait". To keep the plant owners from shutting down and firing everyone, it's necessary to have some kind of payment structure such that people get paid for being ready to produce, similar to renting a car so that it'll be at your command despite your not using it constantly. There's also an arcane type of "reactive power" that needs to be available in specific areas regardless of where the main power supply comes from.

In conclusion, it's complicated!
Commentary on a mildly interesting book about power grids. If you'd like a more historical (and exciting) look at electricity, see "Empires Of Light", a biography of Westinghouse, Tesla and Edison.
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NuclearPoweredPony Featured By Owner Feb 24, 2017
There are four aspects of power grids that I find interesting and try to learn more about when I can.

GENERATION: What it sounds like your book talked about mostly. Obviously I have high hopes for fusion power but if that doesn't get here before cheaper space travel does we might see a revival of the orbital power satellite concept where a large platform of solar cells is put into orbit and then transmits that energy back down to earth either through lasers or microwaves.

STORAGE:  I generally have no faith at all in wind and solar unless we find some kind of revolutionary upgrade to our ability to store power. hydroelectric power does offer a limited form of on demand storage but the rivers of the world are almost all utilized for this already, in China you could make a case for hydro being over utilized.

TRANSMISSION:  This to me is the scariest part of the powergrid, because a solar flare or electromagnetic pulse could ruin the entire grid of a continent until such a time as it gets repaired and replaced.  Say that the grid is down for a week.

In canada in the middle of winter that would be a week where your homes heater doesn't work and you might not be able to start up your vehicle because you cant plug in the block heater.  In other places thats a week in which you have no refrigeration, no access to banking, no net, no tv, no traffic lights, no cell phone signal...  And even once thats all fixed ground side you still have no internet because orbital satellites are likely to be destroyed and might not be replaceable at all if THIS happens…

And thats assuming it gets fixed within a week, which might be ambitious because as far as I know there is currently no contingency planning done either on a state/provincial or federal level in the US or Canada for what to do if this happens.

USAGE: The last area of interest. I was really surprised when I heard the idea of using electric car batteries as crowd sourced power storage, Im not sure how people themselves would feel about their vehicle batteries being drawn on in such a fashion as they are the ones who have to pay to have the battery replaced eventually but it is definitely an intriguing idea.

But that sword cuts both ways because while there would be a massive increase in storage capacity you would also have to deal with a massive increase in energy production and transmission to feed all of those electric cars. Of course this brings us back to talking about storage again because with a battery that large in every household it could make household solar power affordable for the populace at large rather than now where its basically a hobby for survivalists and environmentalists. (which reminds me of a story where a person in california wanted their solar panels installed on the side of the house facing AWAY from the sun because otherwise his neighbors wouldn't be able to see his spiffy new environmentally friendly solar panels. 8)  )
Catprog Featured By Owner Feb 24, 2017
Down here everyone can afford solar panels (Half due to cheap and half due to costs of of grid electricity)

One thing I have heard suggested is you pay the utility a cheap rate and they make sure your car battery is charged to 90%. They get the other 10% to play with.

As for solar facing. I have heard paying people to install to the west not north/south. Optomise generation in the afternoon.
KSchnee Featured By Owner Feb 24, 2017  Student Writer
We should pre-emptively station George Clooney in orbit.

The author's comment about solar flares was that the damage seems to be due to massive current flows into the ground, and that a key part of preparing for that is to install big resistors on the grounding wires. I don't know enough to comment on that, but elsewhere I've heard we should be stockpiling some big transformers and have a plan to put them into position quickly if there's a catastrophic grid failure. We should be doing that anyway in case of an EMP attack, so it's justifiable as a national defense measure if nothing else.

The author's opinion on living off the grid, or my next question ("why not a small neighborhood/town grid?") was that it's more trouble than it's worth. Besides needing to maintain more hardware such as a DC->AC converter, your small system needs capacity to handle some surprising spikes in demand like extra current that some motorized machines need when first starting.
Catprog Featured By Owner Feb 24, 2017
Down here we have had a problem with non-renewables not being reliable. (The operator misjudging demand and not telling the gas generator to turn on.  )

Also our grid is rather large at 5,000km(~3000Miles) with 40,000km of wire (based on wikipedia.)

The car battery example is really a lot of small generators when you think about it.

One of our regions used to have a coal plant that could not run due to low power prices. Now when the wind blows prices are very cheap, When it doesn't, the gas generators make a lot of money.
KSchnee Featured By Owner Feb 24, 2017  Student Writer
I assume it's a continent-wide grid?

The author mentions "smart grid" technology while complaining that it's vaguely defined. One part of it that'd be helpful is more reliable, detailed stats on power demand and supply, which could help with situations like the one you mentioned. Some improvements due to sensors are subtle: power lines sag when in heavy use, due to heat; a good chilly wind helps un-sag them; awareness of the wind can make it safe to run more power through the lines than would normally be considered safe. Other misjudgments are tough to judge even with sensors; the author mentions a surprising drop in demand that caused people in the control room to say "what just happened?" Answer: millions of people had suddenly shut off their TVs right after hearing the jury verdict in the OJ Simpson trial.

I wouldn't call batteries "generators" since they're not truly a source of energy, only storage. You still need the energy to come from somewhere.

About wind vs. gas prices: those gas generators might run even when the wind is blowing, as "peaker" power supplies that turn on (or up) when demand is high. The grid managers try to minimize the cost of the energy they bring online, but there are a bunch of factors they have to consider beyond "is a natural gas plant cheap?" Especially if they're dealing with CO2 laws. Credits/subsidies for buying renewable energy are a little silly because it's not like you have two power lines going to your house, coming from "clean" and "dirty" power plants on separate circuits.
Catprog Featured By Owner Feb 24, 2017… is what happens when you lose many power lines.
Catprog Featured By Owner Feb 24, 2017
half-continent. (to use a usa example. I think roughly Maine ,Cuba, Wisconsin  , Texas would be the points on the edge)


Also in the UK eastenders ending causes a large surge in demand.


I was talking about moment to moment grid operation in calling them generators. (technically they can also be consumers)


Also stability for the grid to run the gas plant. (As I speak 252MW Gas, 424MW wind, estimated 438MW small solar)


For the two power lines comment.

Clean plant produces 100MW.  Dirty plant produces 100MW.

If someone wants to buy the clean part of the 100MW their are two options. Either you build two grids, set up a complex inter connector at anyone who wants to buy it.

Or both types of plants operate the same, they both put their power onto the grid, they sell it as normal. Grid operator does not care if it is clean or dirty.  Then who every wants to encourage the clean part gets to participate in a secondary market outside of the grid.
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Submitted on
February 23