Power surges in Britain caused by millions of people making tea [video]

http://www.bbc.co.uk/britainfromabove/stories/people/teatimebritain.shtml

by shrikant • 14 years ago

386 275 14 years ago

bbc.co.uk

pixie_2• 14 years ago

It begs the question why can't the operator watch a computer that does the operator's job for him. Is split second power allocation really done better by a human? Note I'm not suggesting computers are perfect operators, just less error prone.

itcmcgrath• 14 years ago

Just a note: 'It begs the question' doesn't mean what I think you think it means.

jamesaguilar3• 14 years ago

1. if a statement or situation begs the question, it causes you to ask a particular question It's all very well talking about extra staff but it rather begs the question of how we're going to pay for them.

-- Cambridge Idiom Dictionary, 2nd ed.

IvyMike2• 14 years ago

Notably, it does not mean what the logical grouping of those words would mean: "begs for the question to be asked".

Of course, I believe I've seen "begs the question" used correctly exactly never, and there's an obvious need for a pithy idiom for "begs for the question to be asked", but we don't really have one.

This once again awakens my suspicions that the English language is an elaborate practical joke. And I say that as a native speaker.

politician3• 14 years ago

I hate this trivially predictable response. Similar to observations of Betteridge's Law of headlines, "begs the question" corrections just seem like HN karma pumps.

TamDenholm3• 14 years ago

This is exactly what i was thinking, even though the finish time of Eastenders might not be what the BBC says it is, its not like it would be hard to write a program to listen for the "Dun, dun dundundunduuun" and turn up the power.

polymatter2• 14 years ago

That's probably too brittle a solution. Eastenders ads, other programs etc. could conceivably play enough of the Eastenders theme tune to trigger unnecessary power surges.

enneff• 14 years ago

I don't know. I haven't heard of any major outages as a result of this guy not doing his job properly, and if it's just the one guy... why replace him with software? It doesn't seem worth it.

kintamanimatt2• 14 years ago

The good thing about humans is they have very well-written exception handlers built in!

Such a program is likely to be brittle and could fail unexpectedly requiring human intervention. There are also many other events that couldn't be triggered, such as the beginning of commercials for non-BBC shows, the beginning and end of popular sporting or other TV events that would trigger the same phenomenon. It's probably far simpler and cheaper to have someone sit there and press buttons, with the added bonus of high accuracy.

saidajigumi• 14 years ago

Fine, that solves the problem for exactly one ephemeral correlate of power consumption surges. What about the next one?

If we're talking armchair first-stabs at automation, I'd much rather have 1) a large set of historical data from distributed consumption data feeds across the service area and 2) analysis of that same data live and with near-realtime latency. Given that, it seems plausible that a well-chosen machine learning based system could provide useful automated assistance.

That said, there are a bunch of practical reasons why it probably never makes sense to take human judgement out of the equation, esp. given the potential infrastructure impact here.

politician3• 14 years ago

An explicit signaling solution seems more appropriate here. Suppose the BBC were to embed a frame containing a time-remaining flag at various points in the broadcast. Then the power guys could write some software to watch the stream for these frames, decode them, and estimate the spike.

If necessary, legislate the presence of the frame.

toyg5• 14 years ago

And then EastEnders changes the tune ever-so-slightly (without notifying National Grid operators, of course), and the program breaks. Or the soap gets moved, or cancelled, and the program breaks.

polymatter2• 14 years ago

If you're paying for an operator anyway, you may as well get him to do the job rather than spend all that money on a computer and have the operator watch the computer. The operator is likely to need rotating in a watching job like that too, further increasing costs (I believe CCTV operators need to be rotated every 20 minutes, but that may be misremembering).

Unless you're suggesting that people can trust the computer to do it unobserved then there is little value in having the computer there. Which is a case, I might agree with. My first thought is I would absolutely love to have that job. I'd pay to have that job. Then I could optimise the hell out of it.

scaphandre2• 14 years ago

I'm sure it is at least partly automated, but showing a computer screen doesn't make for as much drama on TV.

alan_cx• 14 years ago

Can you take a computer to court if something goes wrong? The British tabloids need some one to blame, and a computer isn't that photogenic. It has to be a human scape goat.

patrickyeon• 14 years ago

This also happens in Canada, but synchronized to hockey games (predictably). http://www.patspapers.com/blog/item/what_if_everybody_flushe...

hackerboos• 14 years ago

I once heard that the surge happens during the break of Coronation Street.

greenyoda3• 14 years ago

In the U.S. we have this water demand spike at half-time during the Super Bowl.

maxerickson• 14 years ago

The big difference there is that there are thousands of separate water systems meeting the demand.

critium• 14 years ago

To the sounds of several million toilets flushing!

hellgas00• 14 years ago

You can actually view electricity production on an hour by hour basis in Ontario. After a big game finishes in Ontario, there is generally a spike in the production of electricity.

http://media.cns-snc.ca/ontarioelectricity/ontarioelectricit...

adanto6840• 14 years ago

That's pretty cool..

sippndipp• 14 years ago

Jeesh I'm so happy that I'm a rails engineer. How can I follow him on twitter?

afandian• 14 years ago

Unique British problem caused by tea. What must you Americans think of us? (is it true that Americans don't have enough power through the mains to boil a kettle?)

jdminhbg• 14 years ago

That's not true, although it does take a little longer here than in the UK.

Mainly, we just prefer coffee.

jvehent• 14 years ago

And pop-corn machines...

scaphandre2• 14 years ago

Is that tongue-in-cheek? Of course they can boil a kettle.

It does take ages, though.

Conventional kettles seemed to take perhaps twice as long to boil in CA than in UK. Boiling water at 230V,13A in the UK is going to be much faster than 120V,15A in the US.

wglb2• 14 years ago

Um, no.

Heating rate is a function of wattage, not voltage.

EDIT: my error. I neglected to notice the amps shown and just picked up on the voltage.

csense• 14 years ago

Assuming you're heating 300 mL of water. The specific heat capacity of water is 4.2 J / (g°C) [3]. If you're heating it from 20°C room temperature to 100°C boiling, that's a temperature increase of 80°C. The metric system is set up so that 1 mL of water weighs 1 g (give or take a little based on temperature, pressure, impurities, etc), i.e. the density of water is 1g / mL. Plugging in the numbers:

  (4.2 J/(g°C)) * (1 g/mL) * 300 mL * 80°C = 100800 J

So approximately 100 kJ of energy is needed to boil 300 mL of water. One kW of power is a delivery of one kJ per second.

How much power do we have available? In the UK, there's 230V * 13A = 2990 W ~ 3 kW. In the US, there's 120V * 15A = 1800 W = 1.8 kW.

So in the UK it takes 100 kJ / 3 kW ~ 33 seconds. (One kW is 1 kJ / s.) In the US it takes 100 kJ / 1.8 kW ~ 56 seconds.

These times are likely lower bounds. Assuming the voltage and current given by the parent are correct (or you measure them directly and substitute those numbers) and you measure out exactly 300 mL of distilled water, the biggest source of error is probably the fact that you're heating more than the water. You also have to heat the resistor in your kettle or electric stove, the thermally conducting, electrically insulating housing for the resistor, the kettle itself, and the surrounding air. And water molecules heat unevenly (my thermodynamics is a bit sketchy but I think this is called a Boltzmann distribution [2]?) so a few will evaporate before the water reaches a uniform 100°C, carrying off energy.

My guess would be that the above effects matter less in the UK because the higher power means they would have less time to operate.

I'm pretty sure that this analysis deals correctly with the fact that the current is AC [1]; if any experts on the mysteries of power engineering want to correct me, please do reply.

[1] http://en.wikipedia.org/wiki/Root_mean_square#Average_electr...

[2] http://en.wikipedia.org/wiki/Boltzmann_distribution

[3] http://en.wikipedia.org/wiki/Density_of_water#Heat_capacity_...

acomjean2• 14 years ago

In the US in the places I've lived, Ive uses and continue to use municipal gas to cook, and boil water for tea. It heats up water fast. Doesn't strain the electric grid but has other issues.

finnw5• 14 years ago

Does gas not have exactly the same issue? i.e. mains pressure drops when many people in the area are using it at the same time?

danellis2• 14 years ago

American power does seem a bit lacking. Turning on the hoover makes the lights dim.

sbierwagen• 14 years ago

Branch circuit voltage sag, from running the vacuum on the same circuit as the room lighting. Doesn't happen in commercial buildings, where the lighting runs on 277v.

rmc7• 14 years ago

(is it true that Americans don't have enough power through the mains to boil a kettle?)

Wait till you find out that they don't really use kettles. They put an old fashioned pot/kettle on the oven hob....

Thrymr• 14 years ago

Though mostly we just go out to Starbucks.

vineel• 14 years ago

I thought some clocks used the frequency of the power grid to keep time. How are they reliable if it keeps fluctuating so much?

lkbm• 14 years ago

Frequency as in the alternating current alternates direction fifty times a second (or sixty in some countries), not as in power usage is consistent throughout the day. This didn't change the frequency. (Disclaimer: I haven't finished watching the video yet.)

EDIT: Oh, snap. Seriously? You're right, I'm wrong. Sorry.

greenyoda3• 14 years ago

At least in the U.S., they deliberately adjust the speed of the generators so that the frequency averages 60Hz over time. They may lose a few cycles during periods of high demand, but they make up for it later. The clocks in my house that are driven off line voltage are very, very accurate over the long term; I only need to adjust them when daylight time changes. (This is much more accurate than my wristwatch or my car's clock, which need frequent adjustment.) Since I don't have to set my alarm clock or time my cooking with split-second precision, this works out well.

Mindless2112• 14 years ago

They do. Most likely the frequency is adjusted during night hours (when there is less fluctuation) such that the average comes to 50 Hz (or 60 Hz in the US). (See [1].)

[1] http://en.wikipedia.org/wiki/Electric_clock#Accuracy

wglb2• 14 years ago

They do. Over a day, they end up getting the clock back to the proper time.

Keep in mind that in a complex power system (any modern system in an industrial company) that there are multiple interconnected power-generating elements. The difference between a motor and a generator is simply a function of the relative phase. that is to say, if there are two interconnected generators operating, the one that is slower will draw power from the other proportional to the relative phase angle between the two.

The story told is oversimplified, as they are only noting one particular type of event (turning on kettles at the end of a TV program), whereas in any complex interconnected power system, there are events that are much less predictable.

I suspect that in lots of systems that it is much less manual than the video shown.

mynameishere• 14 years ago

What? How is that not insane when a 2 dollar watch can use quartz with near-perfect accuracy?

lttlrck• 14 years ago

Plenty of electro-mechanical heating timers work in this way.

btbuilder• 14 years ago

Even better than that - in Britain they can allegedly prove/disprove when a recording was performed by analyzing the electrical grid:

http://www.bbc.co.uk/news/science-environment-20629671

radiowave2• 14 years ago

Before they started making electric organs, Laurence Hammond's company made luxury AC clocks. The problem was that they didn't keep very good time because of fluctuations in the grid frequency. The story goes that he solved this problem by making gifts of his clocks to the executives of all the power companies in the areas he was selling in to, and within a few months, all his clocks were keeping perfect time.

mrb2• 14 years ago

The demand is increasing by 3 gigawatts in less than 5 minutes, right at the end of a popular TV show. The operator who oversees the whole grid has a TV to be able to watch the show, to know exactly when it ends and be prepared. That is insane.

The demand for the whole country is ~40 GW on average. That's an 8% increase in 5 min.

thaumasiotes• 14 years ago

actually, what strikes me as insane in that summary is that the end of a popular TV show might not occur at a fully predictable time. Barring preemption, I think of TV shows as occuring with clocklike regularity, and even with preemption, it's more common for the interrupted show to make like nothing happened and just air the parts that would have been showing then anyway, than to air over an altered time period. Is british TV so different? Why does the operator need a TV to know when a show will end?

supergauntlet• 14 years ago

Perhaps he wants to know when most people will leave? While a show might end at the hour mark, the important bits will end at different locations near the hour mark, and he might need to judge when viewers would be most likely to stop watching?

scrumper5• 14 years ago

The best example is sporting events. I mentioned half time in the Cup Final in another comment: there's a referee-determined amount of injury time added to each half of the game, then that is subject to the ref (who is, as is required by the job, blind) bothering to check his watch. It's impossible to point to a given five minute window when the game will end.

And yes, British TV is pretty different, at least on the main channels. Over-running programmes will push everything else out to start later, rather than simply starting five minutes in.

TV shows - even in the USA - start all over the place, they are absolutely not 'clocklike' at all. So bad even TiVo has a hard time getting it right.

abraham• 14 years ago

They actually cover this in the video. The operator is given a time when the show is ending but the time is actually incorrect so he has to watch the TV for instances like that.

philwelch2• 14 years ago

What makes having a TV in the power station a bad idea anyway? It's a very simple, very reliable solution.

StavrosK2• 14 years ago

That doesn't happen in Greece. Shows usually air within five minutes of their specified time, but it's not clock-like by any stretch.

One show, in particular, regularly airs 40 minutes after its specified time. I find countries with TV shows that air exactly when they're supposed to to be almost magical.

toyg5• 14 years ago

You clearly don't live in Britain :)

"EastEnders" is the most-followed national soap-opera (rivalled only by "Coronation Street"(aka "Corrie"), but that's not on BBC and has a more Northern focus, so I guess Corrie's kettles are less powerful? Who knows). It's aired twice every day except Sunday (when they air all episodes for the whole week in one go). Like every soap, it will end every episode with a carefully-timed emotional cliffhanger. Episodes are filmed well in advance, but edited fairly close to the actual airing date, to avoid too many plot-leaks. Hence, episodes can be slightly longer or slightly shorter, and they usually make up for it by cutting the credits reel (which starts with the famous "tum-tum-tututum" sound you hear in the video); nobody cares about that, of course, so I guess programmers are just guaranteed "at this time there will be credits", which is not enough for the "electricity watcher" because people will fire up their kettles as soon as credits roll.

Cutting short actual EastEnders footage to accomodate some abstract timing issue would result in a lot of angry calls to the BBC!

viraptor• 14 years ago

Right... and I thought that the story about the destruction of Melmac was crazy:

"In Pennsylvania 6-5000, Willie asked if the reason the planet was destroyed was nuclear holocaust, but ALF claimed it was because every Melmacian plugged their hairdryers in at the same time. If this theory is true, it must be that the power system of Melmac is linked directly into the core & the energy surge would cause the planet to detonate."

Florin_Andrei• 14 years ago

In other words, video on demand saves the grid.

josscrowcroft• 14 years ago

This is hilarious, had me searching for the post date to make sure it wasn't a late-picked-up April Fool's joke.

nandemo• 14 years ago

Does that mean that Brits use electric kettles, or they use regular kettles but stoves are mostly electric (instead of using gas)?

finnw5• 14 years ago

Electric kettles. Regular kettles are not popular here (I had difficulty finding one a few years ago)

waqf• 14 years ago

What you call a "regular kettle" is to us a hilarious archaism.

tomaisthorpe• 14 years ago

Brits use electric kettles. I think I know one person that uses a kettle on a stove, and she uses gas.

Mvandenbergh4• 14 years ago

Almost universally electric. Remember that (being essential for tea) they may be used many times a day and be found in offices and other places without other cooking facilities. Unfortunately, you can't make tea correctly with moderately hot water like what you get from some water coolers. The tea won't steep correctly.

vwoolf• 14 years ago

Depends on the kind of tea. For black tea, near boiling is good, but for whites and oolongs it's not. Though I suppose the British are famous for black tea.

(I got a electric tea kettle with a built in thermometer not too long ago, so this is an interesting issue for me.)

kokey2• 14 years ago

Some people put a cordless electrical kettle on a gas stove, and melt the bottom and damage the kettle. Seriously, I've seen this happen a number of times, I've almost done it myself.

TeMPOraL• 14 years ago

Electrical kettles are plastic. How on Earth do those people think that putting anything made of plastic on a gas stove is a good idea?

eru7• 14 years ago

They use electric kettles. Electric kettles are more useful in countries with 220/230V mains than in countries like the US with 110V mains.

roel_v4• 14 years ago

Sorry for being thick, but why is that?

a-priori• 14 years ago

Canadian tea drinker checking in. I've used an electric kettle all my life and don't see what the problem is...

Electric kettles are common here even though we use 110V power. I've never timed it, but I think they can bring cold water to a boil in maybe 3 minutes, which is okay with me.

If electric kettles are rare in the States then I think it's because of a cultural difference, not because of the mains voltage. Sure it would be convenient if kettles boiled faster, but I don't think it makes that much of a difference.

adrianhoward• 14 years ago

We almost universally use electric kettles - to us they are regular kettles.

The US/UK difference is mostly due to the electric supply I think. At 230v with a max draw of 13Amps per socket UK electric kettles boil fast compared to US ones in my experience.

rmc7• 14 years ago

They would always use electric kettles. The idea of putting (basically) a pot on a stove to boil water sounds like still going outside to an outhouse to go to the toilet.

When renting a house for a holiday in USA once, my family went out to buy an electric kettle to make tea & coffee, and they weren't as common in shops as we thought. That was a weird eye-opener.

toyg5• 14 years ago

In Italy, very few people would own an electric kettle, or even a classic one.

I've travelled a fair bit and I've never, ever seen as many kettles as in Britain.

officemonkey• 14 years ago

Frankly, it's because people in the U.S. don't make tea very often. It's usually just once in the morning, during breakfast (if that.)

gadders• 14 years ago

Normally electric, but we use a kettle that sits on a gas stove for aesthetic reasons.

JosephRedfern• 14 years ago

Very interesting. I live just a few miles from the Dinorwig hydro plant that is mentioned and have been on a tour. It's and incredible feat of engineering - if ever you get the chance to go there (or somewhere similar), I'd recommend it.

bluepaper• 14 years ago

Absolutely, I live quite near by to and highly recommend it to anyone interested, I've been a few times now, and would quite like to go again. For those who are interested: http://www.fhc.co.uk/ There's Ffestinog further south too, but there isn't a tour around that like the one at Dinorwig.

afarrell• 14 years ago

I'm a bit surprised that they are using Hydro power to handle the extra demand, given that natural gas turbines generally are easier to locate close to urban areas. However, their marginal costs are lower. I'm more surprised that this is done manually. In the US, or at least in New York State, this is a market system and scheduling is done by a big 'ol linear program. It takes the supply curves from power plants, the amount of energy required by each region, and the constraints imposed by the physical limits of power line capacity, and solves for the lowest overall cost required to power New York State.

To be more detailed: For a given region, the algorithm schedules the lowest-cost sources first and keeps adding higher and higher cost sources until it reaches necessary generation capacity. Then, everyone is paid the same rate as the the marginal watt that just got scheduled. As a consequence, sources of power which cost money to shut down, like nuclear plans, will actually bid negative into the market to ensure they are scheduled. This is followed by low-marginal-cost plants like hydro dams. Then coal, which is relatively cheap. Then natural gas which is more expensive (or at least was before fracking) but the turbines for which can respond quickly. This actually happens twice as they run this market once the day before based on predictions and then run an adjustments market in real time. IT is actually possible to sell power in the day-ahead market and sell it in the real-time market without owning any generation capacity and do arbitrage. Another way to do arbitrage is to build two reservoirs and pump water to the higher one at night when power is cheap and then generate hydro power during the day when power is expensive [1]. You can also use flywheels or batteries. There are also markets for ancillary services like standing by ready to generate electricity or decrease generation with a few seconds' notice.

[1] http://en.wikipedia.org/wiki/Blenheim-Gilboa_Hydroelectric_P... Source for the rest of this: I interned at the New York ISO four years ago. Read more here: http://www.nyiso.com/public/about_nyiso/understanding_the_ma...

scrumper5• 14 years ago

Thing with Britain is that pretty much everywhere is close to an urban area. The National Grid is truly that: national. Hydro comes online instantly, faster even than gas. It's perfect for these unique-to-Britain spikes.

The interesting parts of this video are the reasons why it's needed to be done manually: catering for spikes in demand which are easy for humans to predict, but very hard to provide for algorithmically. Commonly it's stuff where a significant chunk of the nation is watching the same program on TV. For example, half time in the FA Cup Final; the end of an important episode of a nationally-loved soap opera like Eastenders; the first commercial break in the new series of Downton Abbey, that sort of thing. On those occasions nearly everyone will go to their kitchens and switch on their electric kettles to make tea at the same time. The extra demand of 14 million one kilowatt kettles all going on at once is gigantic and instantaneous, and on a whole different timescale to the kind of day-by-day market pricing and scheduling you're talking about.

I don't think there's any equivalent in the USA at all. There's no spike in demand during the Superbowl half time, for example; the most you'd get is a little bump as everyone opened their fridge doors at once to get another beer. The only similar thing I can think of is the drop in gas pressure you get in a major city on Thanksgiving.

icegreentea• 14 years ago

Not exactly the same - especially since water gets drawn out of reservoirs (typically) so there's already significant buffer, but here's a plot of water consumption in Edmonton during Canada's gold medal olympic hockey game back in 2010.

http://chrisblattman.com/2010/03/08/graph-of-the-day-canadia...

gmac• 14 years ago

(And I think most electric kettles are actually 2 or 3kW, so that spike is even bigger).

timthorn3• 14 years ago

Moreover, electric kettles seem extremely rare in America.

robocat12• 14 years ago

I am more surprised they didn't mention load control i.e. turning off consumer or industrial loads.

If consumers use electric hot water cylinders or thermal storage heaters, then that uses a massive percentage of consumer power usage. It can be automatically reduced by using ripple control to turn off.

Perhaps they already have turned off those demands during peak base load evening hours? Or maybe that part is already automated and the person in the video is dealing with the excess usage above that? I think in the UK it is very common to use gas powered hot water, and boilers for central heating, so perhaps load control opportunity is not significant?

RobAley3• 14 years ago

The existing system works perfectly, with very little increase in costs (the major engineering works were done years ago, Tea after TV has long been part of British life!), so there is no need for a compromise like load shedding.

ollybee• 14 years ago

In the UK there are two systems for reducing loads I know about:

STOR Short Term Operating Reserve, reduce load at short notice and Triad avoidance, always reduce load during peak times.

The data centre I work at does both witching to generator power as needed. We save a LOT of money of power by doing this.

kaliblack2• 14 years ago

The thing that stands out to me is how inefficient kettles are in terms of power usage. Is it a simple case of more power equals shorter time to boil? Is there a more efficient way to turn electricity to heat?

solox3• 14 years ago

Kettles are pretty efficient. Good kettles have tungsten heating elements. Even so, it takes so much energy to heat water because of its ridiculous specific heat capacity (http://en.wikipedia.org/wiki/Heat_capacity#Metrology.2C_the_...).

kaliblack2• 14 years ago

Thanks for the information. I guess it's that I can't comprehend the scale required to make that much of an impact. It's easier (for me) to think at the single unit.

batiudrami• 14 years ago

Of all the types of energy, it's easiest to turn other types of energy (such as electricity) into heat. That's why, when converting amongst other kinds of energy (such as light, or motion), a side effect is often heat (and things getting hot which don't need to be is a sign of an inefficient process).

Essentially the kettle just converts electricity to heat (very efficient) which heats the element inside the kettle which is transferred to the water surrounding it via conduction (also very efficient). There's almost no wasted energy, and you know that because the area around the kettle does not get hot.

Kettles do use a lot of energy because water requires a lot of energy to heat up - in fact it's among the highest of all substances (the measure of this is called the heat capacity or specific heat - the amount of energy to raise an amount of a substance by one degree Celcius/1 Kelvin.

If you want to be more energy efficient at boiling water, put only the amount of water you need in the kettle, rather than boiling extra, but obviously this is not a solution when scaling electricity infrastructure.

edit: I should note that Kettles are not completely efficient - there is still some energy loss (for instance, through resistance in the wiring in the kettle, and heat conducted to the kettle itself or radiated to the surrounding air).

lmm3• 14 years ago

Could one make a heat pump kettle that would be "more than 100% efficient", by moving head from the surrounding air into the water rather than just resistive heating? I remember seeing that approach recommended for heating houses.

eru7• 14 years ago

Kettles with heat pumps could go beyond 100% efficency.

Dylan168073• 14 years ago

There's no such thing as an inefficient way to turn electricity into heat. A light bulb, a television, a fan, a refrigerator, a speaker, a kettle are all going to turn all of their power into heat.

alexkus2• 14 years ago

And given the climate in the UK for most of the year the excess heat means your heating needs to do a little bit less[1].

1. But probably net less efficient in that the majority of houses in the UK use gas for their heating and gas is cheaper than electricy kWh for kWh in the UK.

trainthis• 14 years ago

One gobby bloke in my flat would take the lift and run out for his bits and bobs -- that spanner would come back after a fortnight with a hold-all and straight away put the kettle on, then have an ice lolly.

DigitalJack2• 14 years ago

What did the power draw have to do with the frequency?

greenyoda3• 14 years ago

The frequency of an AC generator depends on its speed of rotation, and an overload can slow it down.

robocat12• 14 years ago

The main buffer for immediate sub-second changes in load is the rotating inertia of electricity generators (e.g. spinning turbines).

When the total power load of the network exceeds the power generation, the immediate load is taken from generators and they slow down. Alternatively if the total load drops, the turbines speed up as they have more mechanical power pushed into them than is being absorbed by the network.

You might think it would be easier to droop the Voltage (lower the load), but for a variety of reasons it works out much better to let the frequency drop (e.g. system frequency can be reliably measured over sub-second periods, frequency is the easily measured everywhere on the network independent of phase, simple control systems before there were electronics).

The whole network relies on this for control purposes. If a network goes out of synchronisation, very very bad things happen - designing for big electricity is true engineering :) e.g. hundreds of millions of people go without power for many hours e.g. design failures in substations and commercial loads can explode due to ginormous power changes!!!

DigitalJack2• 14 years ago

Excellent response, thanks!

spikels• 14 years ago

Reminds me of the apparently fake story that large numbers of people simultaneously flushing their toilets during breaks in the Superbowl damaging sewerage systems.

I wonder if some kind of evil flash mob could bring down the grid by having everyone turn on all their power hungry appliances at the exact same time.

snowwindwaves2• 14 years ago

yes they could bring down the grid that way. as you can see a million people turning on their kettles at about the same time is something that must be planned for. If it happens unexpectedly, it is unlikely the generation would be ready to be dispatched fast enough

J_Darnley• 14 years ago

If you want to make a flash mob big enough to do that you would need to post the information publicly. Then I think there's a good chance of word getting back to National Grid who could then plan for it. The only thing they wouldn't know then is the size of the demand.

Cogito3• 14 years ago

I don't know enough about the English power market to draw comparisons, but I'll outline a little bit about how the Australian NEM (National Energy Market) works and how it deals with situations like this. My understanding is derived primarily from an old house mate who did his electrical engineering honours around the NEM.

A while back the various disparate energy grids in Australia were more-or-less unified into one big grid (well, a few small grids with intercouples), the NEM was established, and the newly formed company NEMCO tasked to govern it.

The NEM is a bidding market, where various energy providers (and interestingly consumers, more on this later) provide bids detailing how much energy they are willing to provide and at what cost. These bids are placed, I believe, at least one day in advance though they can be revised after being placed.

If a providers bid is successful, its output gets adjusted automatically by the NEM to fulfil the quota allocated to it (note: "NEM" is used to describe both the market and the computer system that manages it, as far as I can tell). The providers will be paid whatever the current 'spot-price' is, regardless of the original bid price.

The spot-price is determined by, essentially, greedily consuming the cheapest energy possible until demand is met. Demand is met when the frequency lies within an acceptable bracket (around 50Hz). So a coal power station with high base-load capacity will place low bids for the majority of its capacity, to ensure that it gets picked first when demand is being met. It costs a lot of money to turn a station like that off, so they price their bids accordingly. Gas turbine engines have extremely low start and stop costs but their operating costs are significantly higher. These turbines will price themselves so that they get turned on only when demand is high and the spot-price has increased accordingly.

During some heatwaves in the summer the spot-price can increase to thousands of dollars per megawatt/hour and it is extremely profitable to have a diesel generator hooked up to the grid to take advantage of precisely these situations.

I mentioned before that some consumers will place bids. The realities of power generation mean that a station shutting down can be a long and expensive process. They need to ensure that someone is buying their electricity so that that doesn't happen. Typically this comes in the form of a brokered agreement with a large consumer, such as an aluminium smelter. The smelter agrees to buy a large amount of energy at a certain price (the details are a bit fuzzy to me) and the station ensures that they never drop below minimum load. The thing is, there is a point where the difference between the spot-price on the market and the brokered purchase price is larger than the value of the aluminium that can be smelted with that energy. When this happens, the smelter shuts down its smelting operations and sells the energy back to the market instead.

Now its not so simple as the greedy algorithm I outlined before, for precisely the same reasons as brokered deals happen - physical and political constraints. It's an incredibly complex job to schedule power station ramp-ups and ramp-downs while still balancing the load, but for the most part it's handled by the NEM. It takes into account renewable energy quotas (what my house mates thesis was on), maintenance shut-downs, water supply (for hydro stations) and much more.

One thing in particular that I found interesting was the cost of transporting the energy. There might be tariffs on intercouples between states, but the main cost is actually the distance the energy has to travel. You can't simply turn a coal power station up when a town in the middle of the desert has a power spike, as the attenuation between those two points (well, the closest station that has excess capacity as a result of the increase) means the demand isn't met. Instead, a diesel generator near the town might need to be turned on, which can be very expensive. The grid has a number of way to mitigate issues like this, but it's still very interesting.

The point is, a well written system makes this market work efficiently, but the domain of the problem is still huge. The (mostly) free market takes care of many of the load balancing issues, however human intervention seems unavoidable because there are simply so many things that can go wrong.

[Edit]

NEMCO is now called the Australian Energy Market Operator (AEMO) and their website is at [0]. It has lots of good stuff to look at for the interested. In particular [1] has lots of nice details about the history and structure of the Australian Energy Markets.

[0] http://www.aemo.com.au/

[1] http://www.aemo.com.au/About-the-Industry/Energy-Markets

Mvandenbergh4• 14 years ago

>The thing is, there is a point where the difference between the spot-price on the market and the brokered purchase price is larger than the value of the aluminium that can be smelted with that energy. When this happens, the smelter shuts down its smelting operations and sells the energy back to the market instead.

That seems odd, Aluminum smelters are even harder than coal fired power stations to power cycle. The cells have to kept constantly molten, freezing damages them.

Cogito3• 14 years ago

My understanding is somewhat limited, as that is a second-hand anecdote.

They probably don't turn the smelters off completely, instead simply scaling production down to a minimum. This seems like the most reasonable action in any case, as they would want to continue smelting as soon as the spot-price dropped.

For me the most interesting part of this was the fact that energy brokers existed (not that surprising) and that the free market allowed for instruments like this to be developed.

There are quite a few levels of distribution as well, and each of those implement different market instruments to optimise for reduced risk and costs.

A hard problem that is starting to emerge is actually based on both how distributors amortise risk, and the emergence of smart meters.

Smart meters should be able to help regulate the entire market, because they give us better control over the load profile. The thing is, a typical consumer buys their energy from a retailer, who themselves will have agreements with wholesalers, who in turn work with energy providers and the NEM. Who should have control over the smart meter, its data and operation? Who should benefit from the cost savings and reduced risks?

At the moment the cost savings seem to be shared fairly equally, but ownership of data and control varies based on legislation (state to state in Australia). There is definitely a lot of room for innovation in this space; I'm looking forward to seeing how things progress as more and more of these devices are deployed.

robocat12• 14 years ago

> Aluminum smelters are even harder than coal fired power stations to power cycle

That is incorrect - detailed geeky interesting information in this doc: http://info.ornl.gov/sites/publications/files/Pub13833.pdf

Pot-lines can be turned off for periods of seconds to hours because they have plenty of thermal inertia (assuming the control systems are modern enough, and the power regulations make it profitable for the smelter to do so).

They can also temporarily shift taps (change voltage and power draw) to increase or decrease load, within some constraints.

Only if the pot is turned off long enough to solidify is it a problem - and even in that case if base load prices shift enough it can be profitable to do so in a functioning electricity market, e.g. for a pot cathode that is nearing replacement time they could turn it off earlier than otherwise. In New Zealand they once turned off a whole Aluminium smelter for months when we had a long dry spell and the country ran out of hydro-power (I recall the frozen pots had a > 50% possibility of getting restarted too - the chemistry is somewhat of an art so some luck involved!).

I have two friends who work architecting whole electricity markets (for a whole countries). They have masters degrees in operations research. Pretty cool designing how to set up the pricing, bidding, and rules to optimise for changes base load, spot load, failures, network limits, etc etc. It is hard to design bidding systems to avoid market failures - think Enron & California!!!

If you ever get a chance to visit a smelter, do it, they are damn cool engineering. High current at low voltage (the pots are like huge molten batteries) and the bus-bars cause very large magnetic fields and are apparently dangerous if you were to carry a magnetic tool! IAAEE - I am an electronic engineer - even though I do full-time JavaScript development ;-(

lostlogin• 14 years ago

Background: Scot. English power market? That's somewhere south of this part of Britain.

willyt• 14 years ago

Especially as most of this demand is absorbed by hydro and pumped storage in the Scottish highlands.

chris_wot4• 14 years ago

This is very interesting. I can add to this that the NSW and Victorian governments passed some legislation that all retailers of electricity must offer a percentage of power used be fed into the grid through renewable sources.

Some people go for 100% renewables - this means that if they consume 3Mw power then 3Mw power will be guaranteed to be generated from renewable sources. Would love to know how they calculate this.

The kicker is that they pay for the privilege of using renewable energy, yet they still have to pay a carbon price on their power.

jacques_chester3• 14 years ago

My understanding is that the Renewable Energy Target is actually set by the Commonwealth. Though since it's not really something directly under any S.51 heading I imagine they do it by paying the States and then the States pass the laws to make it work. [1]

I too find it weird that the RET stayed after the introduction of the carbon tax. The entire point of putting a price on emissions is to allow the market to sort out the most efficient way to abate them.

Buuuut of course the RET was started by Howard et al to prop up sugar cane farmers and now it's propping up Gillard's mob in the Parliament. So for now it's unkillable.

[1] On the other hand, when has the concept of limited heads of power ever stopped the High Court from giving the Commonwealth what it wants? I guess they could shove it under 51(i) (interstate commerce) or 51(xx) (the corporations power).

desas2• 14 years ago

They work out how much renewable generated energy they're obligated to provide (or estimate) and ensure that they have at least that much renewable energy generation capacity. The actual electricity supplied to the households doesn't have to be generated from renewable sources.

I imagine.

andrewaylett• 14 years ago

In the UK, I believe that the electricity companies have to provide a certain percentage of renewable, but electricity paid for by people who want "100% renewable" counts towards that target so people are paying the electricity company to do what it was mandated to do anyway. It's not like the electrons coming into your house are in any way connected with a specific type of provision anyway.

vacri2• 14 years ago

The current (conservative) government in Victoria is no friend to renewables. It's brought in rules saying that anyone within 2km of a proposed wind generator has total veto rights, regardless of whether they can see or hear it from their property. There are also six areas in the state where wind generators are simply not allowed, period - most are around coal stations.

I used to work for a company where the owner was also involved in the wind power industry, and every now and then we'd hear things like the above. It ain't exactly being encouraged by our state government, that's for sure.

megablast• 14 years ago

From the front page:

NSW1 $55 10549.74 QLD1 $80.99 6991.47 SA1 $2356.86 2761.4 TAS1 $38.99 1206.17 VIC1 $47.7 7995.27

Look at the value for SA1, this may be because SA is going through a heat wave, where temperatures have reached 47.4 degree over the last few days.

bobbles• 14 years ago

Considering Sydney is predicted to hit 43C tomorrow (highest was 45 in 1939) we can probably see NSW start to spike soon...

Cogito3• 14 years ago

The corresponding graph is very interesting as well [0].

Demand rose steadily from 4:30am through to its peak at 4:30pm. Just after this the spot-price jumped from ~$100 where it had been fairly steadily throughout the day to ~$2300. The market quickly corrected itself, but that half an hour would have been expensive.

Assuming an average price of $2350 per unit, for 2800 units, that half an hour would have cost around $3.43M. In all likelihood the market would have corrected much more quickly than that, but even at half that price it is still a lot of money.

[Edit]

The market is actually calculated in 5 minute intervals, and this graph [1] shows it broken down like that. From it we can see that for 5 minutes the load was at 3050 units, and the price was $12750. The price is an hourly rate, so if this had continued for the hour it would have cost $38.9M. As it was for only 5 minutes, it was actually 'only' $3.24M

Looking at the half-hour averages, this seems to match up, so maybe we were fairly close to begin with.

[0] http://www.aemo.com.au/mms/GRAPHS_NEW/GRAPH_30SA1.GIF

[1] http://www.aemo.com.au/mms/GRAPHS_NEW/GRAPH_5SA1.GIF

robocat12• 14 years ago

> The (mostly) free market takes care of ...

Most electricity markets are highly regulated markets, and the regulations are enforced. You are "free" to trade if you follow the rules.

Read some of the PDFs for http://www.google.com/search?q=electricity+market+design and you can see some of the issues and some of the suggested solutions. Market rules are designed to create a functioning market - like a system architecture - to achieve network reliability, price stability, reduce political interference, and prevent gaming the system (Enron, but gaming can happen anywhere in the system).

Physical electricity connections for consumers are often natural monopolies, and thus require regulation. Imagine you could only buy power from an unregulated AT&T and that there was only one AT&T :-)

It is a very specialised job to design the rules and enforcement systems for a market so that the players (independent suppliers, consumers, and network operators) have the correct incentives to acheive systematic goals.

When the regulations fail, you get Enron and Southern California. When the market rules are not designed correctly, Iraq consumers have blackouts even though their next door neighbour has power to spare, because there is no incentive to build or run a transmission connection between them (e.g. due to fuel subsidies, or political instability). When contracts or the free-market fails, they cause Germany to dump excess wind turbine power to a buyer in another country, but they overload the network of a third party country stuck in-between the generator and load. Regulations are set up to help prevent the whole US eastern seaboard blacking out due to domino effects of network failures and individual incentives of the players to avoid costly redundancy or over-capacity.

99.9xx Reliability costs huge money, and rules help incetivise players to be capable of handling black swan events. Most consumers care about reliability, but most are too small to have any purchase power to effectively influence power producers/network operators (networks have monopolies on connections to consumers, only a very limited number of huge consumers have independent connections).

Deeply hard problems: political, economic, and technical.

robocat12• 14 years ago

http://theautomaticearth.com/Energy/india-power-outage-the-s...

700 million people blackout! Long article, but not very technical, contains some excellent quotes and sound like free anarchy at individual, corporate and government levels - corruption, politics, theft, fraud, overload, fatalaties.

I liked this quote: "No one is taking care of the grid — the network of transmission lines, interconnectors and transformers that is essential to life as we know it; two, supply cannot keep up with demand; and three, rate-setting is a political rather than an economic process. It should not come as a shock, so to speak, that neglect, failure to prepare and playing politics with essentials should lead to disaster ... No less than the American Society of Civil Engineers said in a report released in April that the [US] grid could break down by 2020 unless investment in it is increased immediately by about one billion dollars a year. Why so much? Because, according to the report, more than two-thirds of the system’s transmission lines and power transformers are at least 25 years old, and 60 percent of the circuit breakers have been in use for more than 30 years."

Swannie2• 14 years ago

Excellent excellent post.

I worked in Western Power (Western Australia's distribution power utility) for a short while.

The thing with the smelting plants is that they are usually located far away from population centres, and close to a port (or they have their own port!). This doesn't help with the situation, as they are usually quite a long way from the generation plant. But it usually means they have a very substantial connection to the grid.

I'd love to go back there and learn more about this stuff. Power engineering is fascinating.

amirmc• 14 years ago

Excellent summary.

> "So a coal power station with high base-load capacity will place low bids for the majority of its capacity, to ensure that it gets picked first when demand is being met. It costs a lot of money to turn a station like that off, so they price their bids accordingly"

Nuclear puts in bids of zero since adjusting the power output of those is difficult. Coal is quite flexible once the turbines are running so can be used to deal with upcoming demand (ie if you realise that you need more generation in 30mins time) - apparently this is because they run most efficiently at 70% of max output. Gas generation/stations are most efficient at 90-something-percent of max output, so they have less short-term flexibility than coal. Hydroelectric storage is the quickest to respond but also the most expensive (generation within minutes - some folks I knew called it the 'emergency button' :).

That's all random stuff I learnt years ago over a summer in the industry.

d4nt• 14 years ago

The UK used to have that kind of system (from about 1990 to 2001). Since that time a more complicated system has operated known as NETA[0].

In the current system, generators and consumers (domestic supplier companies are "consumers") trade freely with each other but have to submit notifications to the system operator of the trades that they have done. You trade electricity in half-hours but 1 hour before each half-hour in question you must submit your final notification of your traded position. This profile is what the operator expects you to product/consume over that half hour.

You may also participate in the balancing mechanism[1]. This is where you also submit bids/offers to produce/consume more/less during that half hour. The National Grid will accept bids/offers in order to balance what it sees at the difference between your traded position and forecast demand. If you get your traded position wrong, the grid will have to balance things up by accepting bids/offers and the cost of doing so will fall to you (plus a bit more to teach you a lesson).

The Balancing Mechanism works on a minute to minute type level, to handle second by second fluctuations there is also a service known as Frequency Response which the more flexible generators may provide to the grid. This is a mostly automated system in which their generation equipment continually adjusts to compensate for the changes in frequency.

In the film we saw, at least one Hyro plant was ready to come on. We're not told whether it had sold its power on the open market or had had a bid accepted on the Balancing Mechanism. However, when the French inter-connector trips the Grid brought on another hydro plant. This would probably have been via the Balancing Mechanism. The operators of the inter-connector would have had to pay for failing to meet their traded position.

[0] http://en.wikipedia.org/wiki/New_Electricity_Trading_Arrange... [1] http://www.bmreports.com/bwx_reporting.htm

th82• 14 years ago

What is the reason why Western Australia and the Northern Territory are not a part of the National Energy Market?

tomelgin• 14 years ago

1,500 miles of high voltage transmission lines would cost a lot ($billions). Much more than the economic benefit of sharing power resources across the distinct markets.

AEMO's National Transmission Network Development Plan [0] describes in great detail how they foresee investments in the (eastern) grid infrastructure. As a frame of reference, just upgrading a couple transformers to increase the transfer capacity between South Australia and Victoria will cost tens of millions.[1]

[0] http://aemo.com.au/Electricity/Planning/National-Transmissio... [1] http://www.electranet.com.au/assets/Uploads/interconnectorfe...

dakimov2• 14 years ago

For me it just screams for the question what if that guy will not keep up or just will go to the bathroom? Power outage on the national scale? Frankly that story just blew my mind, all that seems so ridiculous in its hilarious epicness, but very thought provoking. And of course what I did first is checked was not it an April's Fool Day joke. Also the main property of stereotypes is that they often come out to be true. Great post.

eru7• 14 years ago

> Power outage on the national scale?

Just brownout. The hydro will come online a few seconds later.

aj700• 14 years ago

You can monitor the UK National Grid inputs and transfers, sales, demand etc. in almost real time here http://www.bmreports.com/bsp/bsp.php

You need flash, I've never got this page to work in Chrome, but it works in Firefox

tomd• 14 years ago

I wrote a slightly frivolous one-page app which scrapes National Grid frequency data:

http://www.caniturniton.com/

Someone used its API (/api/json) to make a load-sensitive kettle:

http://elsmorian.com/Projects/CarbonKettle

olympus2• 14 years ago

I'm not sure I understand why the spike happens. Is there some etiquette that says you must wait until the T.V. show is finished before you may start making tea (why not switch the kettle on during a commercial break)? Also, is tea in the evening really that popular? Sorry if these are dumb questions, I'm not a tea drinker and I live in the U.S.

pidg• 14 years ago

There aren't commercial breaks on the BBC, it's funded by an annual license fee, so programmes generally run without interruption.

And yes, tea is that popular. In my office, each person will typically drink 3-4 mugs of tea during the day. Many people continue with at least two mugs when they get home.

olympus2• 14 years ago

Thanks for that. Now I need to find out if they are cutting Top Gear and Dr. Who short on BBC America to make room for the commercials...

notJim• 14 years ago

Do people also drink coffee? Or only tea?

ppog• 14 years ago

"Why not switch the kettle on during a commercial break?" The BBC doesn't have commercial breaks. Most UK stations that do have commercial breaks spread them out at about 20-minute intervals, so if you switched the kettle during a commercial break, it would have got cold again by the end of the programme.

Besides, if everyone switches the kettle on during the commercial break, you just shift the spike forward a bit.

rmc7• 14 years ago

Also, is tea in the evening really that popular?

Oh yes. People drink tea throughout the day. Basically black tea with milk and depending on the person sugar. Water is boiled in an electric kettle and poured onto tea bags.

Is there some etiquette that says you must wait until the T.V. show is finished before you may start making tea

It's not an etiquette thing, but more just co-incidence. When a TV show is over, lots of people might want a cup of tea and so it's more that lots of people are doing the same thing at the same time (i.e. a spike).

(why not switch the kettle on during a commercial break)

Channel that have ad breaks would have them every 15 → 20 mins, so the water would go cold.

rurounijones• 14 years ago

if you can find it the BBC documentary "the secret life of the national grid" (3 episodes) is a fascinating look into the history of the UK National Electricity Grid

EDIT: You can find it on youtube if you do a search.

dhruvbird• 14 years ago

EC2 for power!!

jacques_chester3• 14 years ago

And the circle of analogies is complete.

Cloud computing: it's just like your utility!

Utilities: just like cloud computing!

thrownaway2424• 14 years ago

Nevermind the grid, that guy in the video has not just one but several bitchin' keyboards.

peterwwillis2• 14 years ago

If the power grid in the US drops to 57HZ, we're all boned.

Fun fact: Texas is the only state in the union with it's own power grid independent of other states. It is literally the only state that could successfully secede from the union.

sethrin• 14 years ago

Sorry, you mean Alaska and Hawaii have some sort of connection to the rest of the grid, and Texas does not? Or do you mean that Alaska and Hawaii are not states in the union?

Maybe you mean 'most of Texas' and 'only state in the contiguous US'. http://en.wikipedia.org/wiki/Texas_Interconnection

The part of your comment relating secession merits no response.

peterwwillis2• 14 years ago

Sorry, I didn't clarify.

Hawaii's energy needs are 90% based on imported oil. If they seceded, they'd go dark.

While Alaska certainly has the ability to make money off its oil, most of its heating, power and other needs is actually provided by diesel fuel. Add to that the fact that most of the jobs are either government or military related and other industries in the state rely heavily on government subsidies, the state would probably find itself in a real predicament if it cut off contact with its pimp.

caf3• 14 years ago

Without doing even cursory research, I'm still prepared to bet that Hawaii has its own grid :)

snowwindwaves2• 14 years ago

the islands are not interconnected. Hawaii has 7 grids.

brc• 14 years ago

Well, not really. Most European countries are interconnected and EU aside, could easily operate as independent states.

caf3• 14 years ago

The opposite effect happens once a year in Australia, when factories across the country down tools for 10 minutes to watch a horse race, resulting in a large drop in aggregate demand over a short time period.

jacques_chester3• 14 years ago

Thank you for avoiding the cliché.

icambron• 14 years ago

The fundamental issue here is that it's hard to store electricity, so that demand has to be met in realtime. This kind of problem should fade away as cheap grid-scale batteries become available in the next decade.

arankine• 14 years ago

Back in high school, i visited the JET nuclear fusion project in Oxfordshire, they told us that they have to plan fusion experiments so they don't coincide with the end or commercial break of a soap, due to the tokamak requiring (i can't remember the exact figure) ~1 - 5% of the national grid's output.

timthorn3• 14 years ago

Yes, and even then they've stored massive amounts of energy in a couple of very large concrete flywheels to supplement the NG's output.

EEGuy2• 14 years ago

Stepping down from aluminum smelter load levels, consider the comparatively low power demands (orders of magnitude less) of modern lighting and electronics. There's some interesting geekiness to be found in their power demand under varying line voltage.

Voltage-regulated "inverter technology" electronics can, ironically, behave less "linearly" under adverse supply voltage conditions than resistive loads such as incandescent lighting and electric kettles.

Electronically-ballasted fluorescent lighting, CFLs, computer power supplies, VFD motor drives, "inverter technology" microwave ovens all electronically regulate their current draw inversely against voltage supply changes. Voltage goes down, current draw goes up, power demand remains ~relatively~ constant.

So when a brownout (voltage sag, not an outage) comes along, to some extent, these "well regulated" devices hide it from the user. You might not see a "brownout": The electronically ballasted fluorescent lights don't dim so much -- or at all --, your laptop computer keeps running fine if the sag doesn't drop too much, and any DC-powered fans won't necessarily slow down so much or at all. But maybe you heard a universal motor somewhere slowed down. Or maybe the lit-up display area on your old CRT monitor (is anyone still using those anymore?) shrinks 10% then comes back. You hear your computer's desk-side UPS click in (if it has a relay, cheap ones do) then back out but don't see the lights dim. I've seen and heard this and found it rather jarring.

The term "brownout" may become an anachronism (perhaps it has already), not because brownouts don't happen anymore, but because they don't dim the room lights anymore.

To see how much variation a small "non-dimmable" CFL will tolerate, I just put one on a variable transformer and lowered the line voltage gradually from normal (120 Volts) downward. Here's what happened: o It lost very little brightness until about 60-some Volts o Below that threshold, it just turned itself off

As a device user, this is what I'd expect of a "well-regulated" device that runs on mains (grid) power.

But I don't imagine such "well regulated" loads make grid dynamics marginally easier to control under the severe conditions which lead to voltage sags. Probably not much worse though, considering all the heavier loads a grid must support.

robocat12• 14 years ago

I wonder if this is offset by industrial loads that are integrated into the network to drop their loads within milliseconds or short timeframes? Large server farms that do offline processing can instantly turn off large loads without problem e.g. Youtube background video processing.

India has perverse loads too: "Microtek, an Indian company that specializes in selling power backup inverters, claims to have 100 million satisfied customers.". I have read of the same thing happening on water networks, where individual households connect pumps to the the public water supply to suck water when pressure drops too low (supplier can then only restrict rate rather than control pressure, and customers at end of line go without!).

Many Inverter loads have a bigger problem in that they often only suck current at the peak and nadir of each voltage swing (Volts), leading to an ugly non-sinusoidal current waveform (Amps) with odd or even harmonics. Networks add large expensive HV equipment to reduce harmonics. Networks also charge large industrial users more if they have bad current waveforms (either harmonics, noise, or power factor).

henrikgs• 14 years ago

The volume slider on the BBC player goes to 11. Brilliant.

kokey2• 14 years ago

I don't know why they say it's unique to Britain. I've visited a hydro station in South Africa a few times where they've shown me that surge, and South Africans have fewer television channels to choose from.

andrewmccall• 14 years ago

I think it's the sheer size of the surge in demand that's unique. It's 1.5-1.75 million kettles going on at almost exactly the same time.

With 25 million homes in the UK that's 6% of them suddenly wanting another 1000w of electricity.

leoc4• 14 years ago

Most UK households have upgraded to 3000W electric kettles by now, I'd guess.

rmc7• 14 years ago

There are some interesting consequences of this. I heard about a "Earth Hour" or something, a campaign for people to turn off their lights (or something) for a hour (or minute) to use less power.

However unless the National Grid can plan for how many people will do it (nigh on impossible), they'll probably wind up wasting power, and more people can be used preparing for everyone to turn things back on, resulting in Earth Hour/Minute actually use more power than if they'd done nothing.

Swannie2• 14 years ago

Yes. This goes around every year Earth Hour comes up. It's a 1 hour shut down. If people actually did this, then yes, the coal power would stay on. Some would be stored (pumped hydro), but most will be burned off.

National Grid do have very good prediction, as per this (old) video.

Power surges in Britain caused by millions of people making tea [video]

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