Author Topic: Germany pays for you to use electicity  (Read 15499 times)

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Offline SeanB

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Re: Germany pays for you to use electicity
« Reply #25 on: May 14, 2016, 12:15:52 pm »
Power stations can absorb power ( somewhat, limited by the cooling capacity of the generation plant, not the steam condensers) by deliberately increasing the rotor current so the generator runs as a synchronous capacitor, and cutting the steam feed to a low level, so the turbine acts as a turbo pump instead and actually heats the stem entering so it is hotter going out than in. As it is still non saturated steam this only increases the load on the cooling condenser, allowing the power station to be a very quick acting ( though insanely expensive) power limiter, so they can safely ramp down coal feed ( or handle the control rod lag on a nuclear reactor that will take 20 minutes or more to start responding to a step change in loading, and which will take hours to drop power level to the desired point) and steam generation to handle a reduced load. Then for a step change up that is enough that the remaining plant can generate without the synchronous capacitor they reduce excitation so it becomes a synchronous motor with unity power factor, only drawing a little power while still being available for ramp up fast.

Big generation plant is not something you can turn on and off fast, black starting a plant will take days before it gets up to full power, and even a plant running at low power with a single steam generator and turbo running will take hours to ramp up the rest to full power, you have to keep it spinning at all times and keep the cooling and lubrication running at all times or you will destroy it. A hundred ton rotating mass does not respond fast to any step change, especially if it involves a massive temperature change and your tolerances are in the sub millimeter ranges for many of the blade clearances. If you have a blade touch you will be replacing large pieces of plant. If you really oops it it leaves via the roof or the wall, and anything in the way goes with as well.
 

Offline botcrusher

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Re: Germany pays for you to use electicity
« Reply #26 on: May 14, 2016, 01:40:05 pm »
Meanwhile here in Ontario when we produce excess they pay the US to use it, and charge us more!
Yep. Sucks to be Ontarian when it comes to that.
As far as i know, it's primarily the Windsor wind turbines that throw excess power into detroit.
 

Offline mos6502

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Re: Germany pays for you to use electicity
« Reply #27 on: May 15, 2016, 12:02:24 am »
Once electric cars take off, it will be easy to take care of this problem. An 85kWh battery will still be extremely useful for grid power storage after it's been used in a car for 10 years and lost 50% of its capacity. Isn't Tesla already making deals with power companies for their old batteries?

Also, if there are many electric cars, a lot of them will be connected to the grid at any given time. Most cars sit either at home or at work. I could imagine power companies paying electric car owners for their cars to be used as a giant distributed energy storage system.
for(;;);
 

Offline FrankBuss

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Re: Germany pays for you to use electicity
« Reply #28 on: May 15, 2016, 10:20:57 am »
Basically there's a very stressed out person in front of a big control panel switching generators on and off to keep the system running at 50Hz.  It's a much bigger problem here in the UK because we all get up at the end of popular TV programmes and put on the kitchen light, put on the electric kettle to make a tea and flush the toilet (water pumps turn on).  It means we get really big demand spikes.
That's interesting, I thought it is all automatic. Video is from 2010, is it still manual? What happens when the frequency drops too much? IIRC all of Europe has one big grid running at the same frequency. I guess the wires across the English Channel would get really hot then.

BTW, for early TV voting in Germany they used the "Lichttest" (light test) : The TV viewers were asked to turn on all lights and other electrical devices, when they were asked to vote for something. Nice stress test of the grid :)
So Long, and Thanks for All the Fish
Electronics, hiking, retro-computing, electronic music etc.: https://www.youtube.com/c/FrankBussProgrammer
 

Offline Jeroen3

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Re: Germany pays for you to use electicity
« Reply #29 on: May 15, 2016, 11:21:10 am »
The same problem applies to water pressure during world cup final half time.
Everybody flushes their toilets.
 

Offline SeanB

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Re: Germany pays for you to use electicity
« Reply #30 on: May 15, 2016, 12:16:21 pm »
Big power interconnects are all DC links, with voltage converters at each end that act as a rectifier one way and as a SMPS the other side, so you can both send power either way on demand and change frequency as you do so.
 

Offline meeder

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Re: Germany pays for you to use electicity
« Reply #31 on: May 15, 2016, 01:27:25 pm »
It was only on that particular day.
In general Germany has about 35% renewable energy.
 

Offline Delta

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Re: Germany pays for you to use electicity
« Reply #32 on: May 15, 2016, 03:28:18 pm »
Once electric cars take off, it will be easy to take care of this problem. An 85kWh battery will still be extremely useful for grid power storage after it's been used in a car for 10 years and lost 50% of its capacity. Isn't Tesla already making deals with power companies for their old batteries?

Also, if there are many electric cars, a lot of them will be connected to the grid at any given time. Most cars sit either at home or at work. I could imagine power companies paying electric car owners for their cars to be used as a giant distributed energy storage system.

Without a major breaktrhough in battery technology, can this dream become reality?  Is there enough lithium for most of the world's cars to be electric, and some large scale grid storage to be built?  I know I sound like a broken record, but I can't see how we can get off fossil fuels without significant leaps forward in storage technology...
 

Offline mos6502

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Re: Germany pays for you to use electicity
« Reply #33 on: May 16, 2016, 01:18:44 am »
Without a major breaktrhough in battery technology, can this dream become reality?  Is there enough lithium for most of the world's cars to be electric, and some large scale grid storage to be built?  I know I sound like a broken record, but I can't see how we can get off fossil fuels without significant leaps forward in storage technology...

There is easily enough Lithium available right now for 10 billion cars. Lithium is more common than lead.

https://www.quora.com/Is-there-enough-lithium-in-the-world-to-replace-all-petroleum-cars-with-battery-electric-vehicles

Lithium can be easily recycled as well. So after 10 years in a car and 10-20 years as grid storage, virtually all of the Lithium in the battery can be reused.

Also, what more leaps in storage technology do you need? We already have cars that can go >500km on a single charge. The Tesla S is projected to get a 1000km range in 2017.
for(;;);
 

Offline Delta

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Re: Germany pays for you to use electicity
« Reply #34 on: May 16, 2016, 02:48:57 am »

Also, what more leaps in storage technology do you need?

Enough to provide the 24GW of power the UK is consuming right now would be a good ball park figure.  And that's at quarter to four in the morning!
 

Offline DenzilPenberthy

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Re: Germany pays for you to use electicity
« Reply #35 on: May 16, 2016, 03:37:11 pm »
24GW / 35.8M registered UK vehicles (June 2014)

= 670W

670W/12V = 55A

I'm going to say that the average capacity of a 12V automotive starter battery is 55Ah. So there is a sufficient number of car batteries out there to power your 24GW for an hour.

I'm not suggesting this as a practical solution but people seem to think it it ludicrously far fetched to imagine manufacturing vast quantities of batteries to provide grid scale storage but no-one blinks an eye that there are at least 35 Million car batteries sitting around out there.  Imagine how impossible it would have seemed once that we would have the resources to manufacture hundreds of millions of precision engineered internal combustion engines or even dig enough asphalt and gravel out of the sand to build a worldwide network of paved roads.
 


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