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electricity: base load, peak load etc (Read 7763 times)

freediver

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electricity: base load, peak load etc
May 2^nd, 2007 at 3:27pm

At the moment Australia uses mostly coal for it's base load supply. Nuclear is also suitable. Base laod energy sources must be relatively cheap and be able to run 24 hours a day. In fact, plants such as coal and nuclear fired cannot be started and stopped quickly because they need large quantities of boiling water.

Peak load is used to make up the difference between base load and the peaks. The fuel need not be as chaep, as a premium can be cahrged during these times. The plants must be able to start and shut down relatively quickly, and sit idle most of the time. They must be available, but not necessarily running, 24 hours a day. Gas is currently used for our peak load supply. It is far more expensive than coal.

A combination of gas and renewables would be suitable as gas plants can be easily shut down when there is an oversupply of energy, and can be brought online for peak loads or when there is an unusual combination of events that causes a distributed system of renewables to run below rated capacity. Most wind turbines operate well above rated capacity most of the time.

Gas turbines would probably be cheaper than batteries in augmenting renewable energy sources to give a stable supply. Gas has slightly more than 1/4 the greenhouse emissions as coal.

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IQSRLOW(Guest) Guest	Re: electricity: base load, peak load etc Reply #1 - May 2^nd, 2007 at 4:55pm Given that our supplies of gas are limited to around 60 years, wouldn't that just be a stop-gap measure?
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freediver Gold Member Offline www.ozpolitic.com Posts: 47436 At my desk.	Re: electricity: base load, peak load etc Reply #2 - May 2^nd, 2007 at 5:05pm I think 60 years is based on base load supply from gas. In 60 years time clean coal technology may be on the shelf. Renewables will also be significantly cheaper. Batteries too, probably.
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IQSRLOW(Guest) Guest	Re: electricity: base load, peak load etc Reply #3 - May 2^nd, 2007 at 5:17pm That's a significant capital expenditure for a relatively short time frame. The ROI may not be attractive enough to make it economically viable.
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zoso

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Re: electricity: base load, peak load etc
Reply #4 - May 2^nd, 2007 at 5:18pm

Forgive me for my ignorance, but don't gas plants use steam turbines just as coal and nuclear do?

I believe also that most coal plants will have multiple turbines, and they can switch off turbines at will without effecting the boiler.

An interesting bit of trivia: Steam turbines are so massive that when shut down they must be kept rotating at some 30 rpm or the shaft they run on will bend under the weight!

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freediver

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Re: electricity: base load, peak load etc
Reply #5 - May 2^nd, 2007 at 5:27pm

That's a significant capital expenditure for a relatively short time frame. The ROI may not be attractive enough to make it economically viable.

I don't think a typical working life of such a plant goes much past 60 years. Also, we will no doubt find a bit more gas as the supply starts to run out.

Forgive me for my ignorance, but don't gas plants use steam turbines just as coal and nuclear do?

I think they burn the gas in something resembling a jet engine, as opposed to using it to boil water.

I believe also that most coal plants will have multiple turbines, and they can switch off turbines at will without effecting the boiler.

There is significant 'momentum' involved. Even if they did switch off a boiler, the coal would continue burning and releasing GHG's. I'm not sure of all the technical details, but they can't be made to be responsive. At least, not cheaply enough.

An interesting bit of trivia: Steam turbines are so massive that when shut down they must be kept rotating at some 30 rpm or the shaft they run on will bend under the weight!

Until they cool down?

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zoso

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Re: electricity: base load, peak load etc
Reply #6 - May 2^nd, 2007 at 7:51pm

Quote:

I think they burn the gas in something resembling a jet engine, as opposed to using it to boil water

I think you are right there.

Quote:

There is significant 'momentum' involved. Even if they did switch off a boiler, the coal would continue burning and releasing GHG's. I'm not sure of all the technical details, but they can't be made to be responsive. At least, not cheaply enough.

Not the boiler, switch off a turbine, I *think* they can anyway.

freediver wrote on May 2^nd, 2007 at 5:27pm:

Until they cool down?

Indefinitely I believe. Not sure on details it was just mentioned in one of my engineering books.

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freediver Gold Member Offline www.ozpolitic.com Posts: 47436 At my desk.	Re: electricity: base load, peak load etc Reply #7 - May 2^nd, 2007 at 8:27pm It sounds like high temperature creep.
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