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Old 03-01-2013, 03:18 PM   #511 (permalink)
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Originally Posted by jamesqf View Post
You completely missed my point, which was NOT that you don't need peaker plants. Of course you do, even in the current system (as your graphs demonstrate). My point is that you don't need to design them in such a way that they idle all the time, burning fuel without generating electricity.

Typical peaker plants are gas turbines, which are basically jet engines. Now does your average airliner sit around idling and burning fuel when it's not flying (or taxiing)? How long does it take to spool up from engine start to takeoff thrust? A few seconds.

Then you figure that wind generation (since that's what you have in the UK) just isn't going to change all that quickly - the wind doesn't suddenly start or stop blowing simultaneously all over Britain, does it? So peaker plants are/should be designed to come on line within that small time.

That also answers your problem with farm/sewage gas generation. Since peaker power is more valuable than baseload, it would pay to store some fraction of the generated gas to use at periods of high demand, rather than supplying baseload.
OK - I misread the idea of turbines being like this - fuel (nuclear / gas / coal / biomass) -> Steam -> turbine -> power

Your idea is fuel (oil or gas really) -> turbines -> power -> grid

So the idea would be that this could smooth the supply from renewables which is unreliable. I need to do more research - is it more efficient to start / stop a gas turbine multiple times vs maintaining nuclear or CCGT as a baseload ? And how do you model it because the wind and solar is so variable ?

Interesting stuff though.

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And you could afford to build new nuclear, or invest in energy efficiency.
Power companies here won't build new nuclear because of the lack of clarity on the energy policy - they get paid on what the grid consumes from them.

If uk.gov continue to give "renewables" a priority then if you build nuclear and in the unlikely event renewables do produce a lot of power, you may end up not delivering power to the grid which means no income.

Same for gas at the moment. And nuclear also involves a promise on the costs of removing the station and dealing / storing the waste.

This is where the Climate Change Act comes in because uk.gov has promised a reduced CO2 output, and at the same time has also said we can have growth. So they give renewables a legislative advantage which it doesn't deserve IMHO.

Madness.

Did you know the UK has the largest amount of nuclear waste anywhere ? We kind of promised to "reprocess" it but that didn't work out so we have to store it - for 100,000 years...

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Which costs money, no? So the question is whether it's more economical for 3rd world countries, which don't have an existing infrastructure, to build one, or to use distributed power systems.
Depends on the country and the region. In the African cities then central power is better, in the remote areas self generation is probably the only resource available.

Maybe if one source was very efficient maybe that would be better than loads of generators ?

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Originally Posted by jamesqf View Post
Given competent engineers with a mandate to design for efficiency, this should be no problem. Plug the tool in, it charges when power is available. The "vampire power" used by the current generation of "wall warts" is an artifact of careless design coupled with a 120/220 volt A/C distribution system.
Agreed.

We have a rating for the power usage of domestic items like fridges and cookers - this seems like something to extend here. Perhaps it could also include every device - laptop, smartphone, power tool, plug-in hybrid - anything we plug in.

That would be good.

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And when you want to use a corded power tool, and the power's out?
But I don't want the power out at all.

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Originally Posted by jamesqf View Post
Well, no, it's not simple at all. Remember that inertia thing? If you dump a major load like an arc furnace on to the system, it's analogous to letting out the clutch with your engine at idle. The system effectively stalls: voltage drops (AKA brownout), the local frequency can degrade enough that it gets out of synch with the rest of the grid, you get separation & islanding. Worst case you can get a blackout over the whole system.

So if you want to put your arc furnace out in the desert, quite a long ways from most generation, you obviously have problems.
Well I don't disagree with what you say - you have studied this after all. Here in the UK no place is much more than 500 miles from any other place so our scale is different.

Here if a company wants to build a plant which is going to suddenly consume that level of power then they will also have to agree with a power supplier to provide that level of energy to a schedule. Something like - "Hi I'm Tata steel and I'm about to take (megaenergy) from you in (insert schedule here)" and the energy producer gears up for it. If the consumer (the steel works) misses their power "window" then they pay anyway. This is a commercial thing, it happens now.

This will probably be arranged seperately to the regular grid supply - which is why a lot of steel places and power plants are quite close together - direct supply as you tapped.

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The bottom line of all this is that it seems that a lot of people insist on saying "can't", when what they really mean is "that's not the way we've always done it". All the problems are fairly simple, technically, and probably less expensive in the long run than maintain the current system. (And that's without even considering the environmental effects of CO2 & fracking.) You just have a lot of people emotionally & financially invested in business as usual.
With respect that is very simplistic. Like you I would love a much more radical and up to date energy system, but we have a huge "installed base" of households, industry and government using the old system to deal with. Transferring all of that to some new tech. means someone has to pay for it all, and someone has to tell them to do it. And maybe it needs a technology change, which in turn needs more energy, materials and so on.

And at that point we enter the world of politics - government regulation vs the market deciding for itself or costs paid by consumers or by taxpayers.

EDIT - or mandated government charges to consumers which is then taken back by government and spent on something else - which is what happens to 11% of my energy bill each year. I think this is another tax, ~80% of my income goes back the uk.gov each year.

Its a tricky one.

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Old 03-01-2013, 03:23 PM   #512 (permalink)
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So is suspect alive, or has he been taken to Mekon ?
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Old 03-01-2013, 11:00 PM   #513 (permalink)
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Very high voltage DC transmission lines are actually more efficient than AC. I don't understand how, but they are. They can transmit power across the US with only about 6% loss, if I recall correctly.
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Old 03-02-2013, 12:23 PM   #514 (permalink)
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OK - I misread the idea of turbines being like this - fuel (nuclear / gas / coal / biomass) -> Steam -> turbine -> power

Your idea is fuel (oil or gas really) -> turbines -> power -> grid
Yeah, "turbine" is kind of ambiguous, and I do tend to economize on typing sometimes :-)

Quote:
So the idea would be that this could smooth the supply from renewables which is unreliable. I need to do more research - is it more efficient to start / stop a gas turbine multiple times vs maintaining nuclear or CCGT as a baseload ? And how do you model it because the wind and solar is so variable ?
It does get complicated, both to think about and to manage, because there are a lot of options (even within an existing grid), and demand is intermittent anyway. Then figure that a lot of thermal plants - coal & gas especially - have efficiency curves (similar to BSFC for cars), so for instance your coal plant may be rated at 100 MW, but operate most efficiently at 90 MW, and get real inefficient below 50 MW. So how do you operate it most effectively? Wikipedia has a decent introduction to load following: Load following power plant - Wikipedia, the free encyclopedia

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Power companies here won't build new nuclear because of the lack of clarity on the energy policy - they get paid on what the grid consumes from them.
Well, that's politics and public hysteria. Doesn't mean that the problem's not fairly simple technically :-)

Quote:
And nuclear also involves a promise on the costs of removing the station and dealing / storing the waste.
Now there's where I have a couple of philosophical problems. First, it seems inefficient to plan on removing a power station. You've got a lot of investment in physical plant, which should be refurbished & reused. Britain shouldn't be any stranger to this idea. After all, you keep your royal family in a dwelling that's going on for a thousand years old Windsor Castle - Wikipedia, the free encyclopedia And of course nuclear "waste" is a valuable resource that can be reprocessed & reused.

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Maybe if one source was very efficient maybe that would be better than loads of generators ?
Maybe. But remember to figure cost of source, plus building & maintaining grid, plus the risk factors of unpredictable fuel costs, what happens when an insurgent group targets the generating plant, etc. Compare it to telephones: why has the 3rd world been so fast to adopt distributed cellular technology, instead of stringing up thousands of miles of copper, like the developed world has?

[QUOT]Perhaps it could also include every device - laptop, smartphone, power tool, plug-in hybrid - anything we plug in.[/QUOTE]

Another thing I've been thinking about. Lots of devices are inherently low-voltage DC. As for instance your computer: the power supply takes A/C from the wall plug, and converts it to 12V & 5V DC, at an efficiency of around 80-90% How much more efficient to run directly off a solar/battery system at 12V. Same applies to modern TVs &c, and then there's LED lighting, and everything with a battery that you plug in to charge.

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But I don't want the power out at all.
If wishes were horses :-)

Quote:
Here if a company wants to build a plant which is going to suddenly consume that level of power then they will also have to agree with a power supplier to provide that level of energy to a schedule.
You need to remember that electricity isn't like say running oil along a pipeline. Everything is interconnected with everything else: if I turn on a light, the power may simplistically come from the geothermal plant up the road, but it's also effecting the nuclear & wind plants in California, coal-fired generation out in the desert east of here, the water flowing through Bonneville & Grand Coulee dams... It's not so much the power that's the problem, though there are still issues of whether the lines will handle it. It's the large intermittent loads that are the real killers. But this gets into the whole area of electric system powerflow & stability, which is complicated. Every time I start thinking about it, I come away amazed that the whole thing actually works at all.
 
Old 03-03-2013, 05:48 AM   #515 (permalink)
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...
I don't really disagree with most of this, and I've learned about load following plants Maybe come back to some of this later, I have a pile of ironing to do

Next month in the UK we are losing 10% of our capacity because of the fear of CO2. Some older coal plants are being closed - at the same time China is adding them at a rate of one a week to one a month and burning dirty coal compared to our cleaner version.

That leaves us with only 5% of spare capacity which is not enough to ensure the lights stay on. And still no fracking although we are sitting on a giant pile of it and using it has helped reduce the US CO2 output quite a bit, if thats your priority.

At the same time apparently wind speed in the whole of Europe is under 20 MPH which means that renewables (wind) miracle is actually consuming power to keep the turbines turning, otherwise they sieze up. 0.02% of capacity came from wind last night.

Not going to bridge that gap is it ?

If there is anything positive about lights going out then it might wake up a lot of the electorate to the dangers of the current energy policy, after all the main parties (who all support this madness) took a major beating last week...

BBC News - Eastleigh by-election: Lib Dems hold on despite UKIP surge
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Old 03-03-2013, 12:35 PM   #516 (permalink)
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Seems the core issue here is that there are a lot of people who put their short-term comfort & convenience way ahead of long-term survival.
 
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Old 03-03-2013, 12:42 PM   #517 (permalink)
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When a lot of people have to decide between heat and eat just because the WWF say so, there is something wrong.
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Old 03-03-2013, 03:26 PM   #518 (permalink)
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Especially as it doesn't seem to do what it is meant to do

Wind farms will create more carbon dioxide, say scientists - Telegraph

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The finding, which threatens the entire rationale of the onshore wind farm industry, will be made by Scottish government-funded researchers who devised the standard method used by developers to calculate “carbon payback time” for wind farms on peat soils.
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Old 03-03-2013, 09:53 PM   #519 (permalink)
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How does a wind farm create carbon dioxide - let alone "more"?
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Old 03-03-2013, 11:21 PM   #520 (permalink)
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In the article, the infrastructure supporting the wind farms out in the middle of absolute nowhere sinks into the damp peat and causes surrounding peat to lift up and dry out... eroding its capability to absorb carbon. Ouch.

 
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