The Power Crisis

[Jantar]

I don't get it.

Baseload stations or not, how can increased generation put more stress on hydro storage?

Please explain for the benefit of myself and the rest of the dumb cunts.

OK, I realise that it is counter intuitive.

New Zealand is on a single time zone. That means that not much generation is needed overnight. Most people get out of bed at around the same time in the morning, so the demand increases rapidly; around 2000 MW increase between 6:00 am and 8:00 am. Baseload stations, are quite slow at ramping, or changing their generation, that is why they are called baseload. Hydro is required to ramp up quickly to meet this increase in demand, and as a result spends a lot of time in an inefficient range. This wastes water, and often requires the use of stored water, just to meet frequency keeping or PLSR that baseload stations can't provide.

Two months ago, when both Taupo and Waikaremoana were low, frequency keeping prices in the north island reached a record high because both Genisis and Mighty River had to use stored water, which was almost not available, to provide those services that baseload stations require.

[McDuck]

I don't get it.

Baseload stations or not, how can increased generation put more stress on hydro storage?

Please explain for the benefit of myself and the rest of the dumb cunts.

Becasue NZs power usage is not uniform. IE there is a high loading between the times of 7am and about 10am then a very high loading between 5pm and 8pm then it backed right off overnight. The 'base load' stations can not (easily) ramp up production around these times so it is up to the hydros than can easely step up production when needed.

[McDuck]

OK, I realise that it is counter intuitive.

New Zealand is on a single time zone. That means that not much generation is needed overnight. Most people get out of bed at around the same time in the morning, so the demand increases rapidly; around 2000 MW increase between 6:00 am and 8:00 am. Baseload stations, are quite slow at ramping, or changing their generation, that is why they are called baseload. Hydro is required to ramp up quickly to meet this increase in demand, and as a result spends a lot of time in an inefficient range. This wastes water, and often requires the use of stored water, just to meet frequency keeping or PLSR that baseload stations can't provide.

Two months ago, when both Taupo and Waikaremoana were low, frequency keeping prices in the north island reached a record high because both Genisis and Mighty River had to use stored water, which was almost not available, to provide those services that baseload stations require.

theif.....

[dipshit]

New Zealand is on a single time zone. That means that not much generation is needed overnight. Most people get out of bed at around the same time in the morning, so the demand increases rapidly; around 2000 MW increase between 6:00 am and 8:00 am.

Which kind of makes large-scale wind farms in NZ a stupid idea, doesn't it?

How do you get the wind to blow at peak demand times?

What happens to excess electricity generated by wind farms during the middle of the night?

[Winston001]

OK, I realise that it is counter intuitive.

New Zealand is on a single time zone. That means that not much generation is needed overnight. Most people get out of bed at around the same time in the morning, so the demand increases rapidly; around 2000 MW increase between 6:00 am and 8:00 am. Baseload stations, are quite slow at ramping, or changing their generation, that is why they are called baseload.

Hydro is required to ramp up quickly to meet this increase in demand, and as a result spends a lot of time in an inefficient range. This wastes water, and often requires the use of stored water, just to meet frequency keeping or PLSR that baseload stations can't provide.

Silly old me. I thought you opened the intake gate up a bit, the water flow increases, the generator spins faster, drags more electrons out of the Earth, and sends them down the line. Or maybe an idle generator spins up.

No??

[McDuck]

Silly old me. I thought you opened the intake gate up a bit, the water flow increases, the generator spins faster, drags more electrons out of the Earth, and sends them down the line. Or maybe an idle generator spins up.

No??

Its complicated.

[Jantar]

Silly old me. I thought you opened the intake gate up a bit, the water flow increases, the generator spins faster, drags more electrons out of the Earth, and sends them down the line. Or maybe an idle generator spins up.

No??

OK, lets see if I can explain it like this.

Just like any engine, a turbine has a set load at which it is most efficient. The majority of hydro stations in New Zealand are Francis Turbines, which generate 90% of their peak power while using only 80% of maximum water flow. However, when connected to the grid and generating nothing (called speed, no load) they use around 18% of maximum water flow. They also have a minimum load, usually around 50% of maximun generation which requires around 60% of maximum water flow. So any generation point that is not at the optimum uses far more water for each MW of generation.

Its just like riding your bike in the wrong gear with the choke on. You use a hell of a lot more fuel to go the same distance.

Now to "I thought you opened the intake gate up a bit, the water flow increases, the generator spins faster". The generator doesn't spin any faster at all. The speed of the generator is locked by the grid frequency, and once synchronised it doesn't matter whether the gates are only partially open or fully open, the speed wont change. A 40 pole generator will spin at 150 rpm irrespective of the amount of water going through it, or the power being produced.

[Fooman]

Now to "I thought you opened the intake gate up a bit, the water flow increases, the generator spins faster". The generator doesn't spin any faster at all. The speed of the generator is locked by the grid frequency, and once synchronised it doesn't matter whether the gates are only partially open or fully open, the speed wont change. A 40 pole generator will spin at 150 rpm irrespective of the amount of water going through it, or the power being produced.

Just to add to this - it is probably worth explaining that as load increases (i.e. half the country putting the kettle on at halftime), the grid frequency will want to drop - to keep it at the required grid frequency, more mechanical power needs to go into the generator - so you adjust the gates to supply the correct amount of mechanical energy to keep it at the grid frequency.

(all the above is ignorant mechanical engineering arm-wavery on an electrical engineering subject, subject to correction)

However, most power generation machines are designed to operate at a set speed, to avoid harmonic excitation and associated stress/strain cycling that can lead to fatigue failure. Therefore you do not want them to operate away from the design frequency for anything more than a few cycles - in NZ it's 50 Hz ± some small amount. I know Transpower at some point asked if some plants could support 47 or 48 Hz for a short amount of time (30 secs?) at full load, to accommodate fluctuations in load. Technically speaking, that would root a lot of expensive kit, so they were told in no uncertain terms, don't count on it buddy.

This is the thing that all the plant and transmission people have to juggle all the time. And it is one of the reasons why I do not begrudge Transpower having the highest % of staff who earn over 100k of any SOE/COE. It's a big responsibility to ensure everyone has power all of the time, which is why, in my opinion, the currently regulatory environment is poor, as it discourages prudent investment in power infrastructure for things like dry years and increasing demand.

It's all well and good having super efficient, high power power plants, but I was chatting to a former head of EPRI (big power research group in the (mainly) US a couple of years ago, and he ranked efficiency below maintainability, inspectability, reliability and most of all: availability of the power supply.

Cheers,
FM

[portokiwi]

I still like the option of wind farms. I saw the all over Europe.
Never heard any neg comments on it.
Wellington has so much even when the wind isnt blowing there is still a lot of wind comming out of the behive.
Wh cant say we dont get much wind and it dosnt take much wind.

[Deano]

I still like the option of wind farms. I saw the all over Europe.
Never heard any neg comments on it.
Wellington has so much even when the wind isnt blowing there is still a lot of wind comming out of the behive.
Wh cant say we dont get much wind and it dosnt take much wind.

I've seen a report that claims that the British and Danish Govt's have stopped ALL further wind turbine generator developments on land because of public health concerns.

Do a google search on windfarms and health or noise.

There is a shitload of debate out there.

[Jantar]

I still like the option of wind farms. I saw the all over Europe.
Never heard any neg comments on it.
Wellington has so much even when the wind isnt blowing there is still a lot of wind comming out of the behive.
Wh cant say we dont get much wind and it dosnt take much wind.

A small amount of wind as a prportion of the total supply is good. It can save either thermal or hydro energy, but only to a limited degree. Once the amount of wind generation exceeds the swing from the frequency keeping station plus Sustained Interuptable Reserve capacity, then wind will help to destabilise the system, requiring hydro to be run inefficiently, and hence waste stored water.

In New Zealand that amount of wind is around 450 MW in the North Island and 170 MW in the South Island.

[portokiwi]

Thanks for that...... I know Portugal France and spain all use N. Power as well as others.

[RantyDave]

It's been widely reported that even the smallest nuclear power station would produce epic amounts more power then NZ would even know what to do with.

By, like, the windmill lobby. You really think the engine in a nuclear submarine produces more power than an entire country consumes?

Dav

[Jantar]

By, like, the windmill lobby. You really think the engine in a nuclear submarine produces more power than an entire country consumes?

The small maritime nuke units are not economic for general power generation, and they don't need to worry as much abot cooling issues. At present, as has been discussed here many times already, there is no nuke turbine/generator unit small enough to be usefull in New Zealand.

It isn't so much that we are unable to use all the power produced, but that we are unable to use all the power produced, while maintaining spinning reserves, frequency keeping and voltage regulation, and at the same time be able to ramp other plant up and down to meet peak and trough demands.

[dipshit]

I still like the option of wind farms. I saw the all over Europe. Never heard any neg comments on it.

European countries network all of their grids together though, so they have a spread of time zones (hence peak demand times) and weather systems.

New Zealand is on a single time zone and is small enough to be affected by the same weather system over the whole country at the same time. The larger you make a windfarm, the more problematic it becomes.