View Single Post
Old 03-02-2013, 12:23 PM   #514 (permalink)
jamesqf
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 808 Times in 592 Posts
Quote:
Originally Posted by Arragonis View Post
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

Quote:
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.

Quote:
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.

Quote:
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.