OT: IEEE spectrum on grid parity in China

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They don't say anything about energy storage and it's associated costs.

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is the published paper (which you can get at for free via the Spectrum link.

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Bill Sloman, Sydney
Reply to
Bill Sloman
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Sheesh, the IEEE ignoring the elephant in the room. Well, OK, it was the Nature-Energy authors who first ignored it, but the IEEE writer continued.

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 Thanks, 
    - Win
Reply to
Winfield Hill

Why is it that everyone talks about the solar elephant while ignoring the n uclear gorilla? The issue is not just the availability of renewables. It is the matching of availability to demand. Nukes are the opposite of wind and solar in that they are available 100% of the time and MUST be used sinc e they can't be throttled. The new plants that could be built are still ve ry expensive to build and operate with the same cost being amortized over f ewer kWh when throttled raising the cost of electricity.

The point is everyone loves to bash wind and solar electricity production b ecause it requires some means of backup, either storage or other generation capacity. But we already have tons of added generation capacity to mitiga te load changes. When using solar or wind power this added generation capa city is shut down accomplishing the intended purpose, reducing production o f carbon. The only added cost is the cost of the solar or wind production. Most of the cost of the additional generation capacity is fuel costs, so it does not cost a large amount to keep idle... after all, that is it's int ended purpose anyway, to sit idle until needed.

Win,

I believe you have solar on your roof. Today it is overcast here. While n ot dark, it is rather grey. What is the relative production you see on day s like this when there is no sign of the sun? What percentage production d o you see compared to the same day with no clouds?

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  Rick C. 

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Rick C

Please explain the physics and/or chemical engineering behind that (mis) statement.

In fact, nukjes power output can be and is, varied. However you do want to do that in a gradual, planned fashion.

There are good economic reasons for running nukes constantly, but that is a different kettle of fish.

Indeed, and such "backup dispatch" costs should be added to the costs of irregular and somewhat unpredictable wind power.

No we don't. The market is designed to ensure that isn't the case.

You appear to have a medium term memory deficit. You have already made many incorrect speculations on the events of August 9th, so perhaps you can be forgiven for forgetting that.

Bugger all in the winter. And the wind power has been known to more or less disappear for up to a week, when there is a blocking high pressure.

Now we appreciate you probably haven't witnessed that yourself, but wise engineers learn from other people's experience.

Reply to
Tom Gardner

Overcast here as well. We made 33kWh today, about 65% of the usual clear sunny day this time of year.

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 Thanks, 
    - Win
Reply to
Winfield Hill

Rick C wrote in news: snipped-for-privacy@googlegroups.com:

They watched "Trading Places"?

Reply to
DecadentLinuxUserNumeroUno

ty

s.

nuclear gorilla?

It's more the nuclear mouse.

of availability to demand. Nukes are the opposite of wind and solar in th at they are available 100% of the time and MUST be used since they can't be throttled.

Nuclear power can be throttled, and the French nuclear system is run at rou ghly 70% of capacity to match supply and demand. Apparently they throttle b ack newly fueled reactors a lot harder than reactors that are coming up for a change of fuel rods. The piece I read wasn't too specific about why.

Teh economics of under-running them isn't great. The capital spent in build ing them still has to be serviced even when they aren't generating maximum revenue.

operate with the same cost being amortized over fewer kWh when throttled ra ising the cost of electricity.

because it requires some means of backup, either storage or other generati on capacity. But we already have tons of added generation capacity to miti gate load changes. When using solar or wind power this added generation ca pacity is shut down accomplishing the intended purpose, reducing production of carbon. The only added cost is the cost of the solar or wind productio n. Most of the cost of the additional generation capacity is fuel costs, s o it does not cost a large amount to keep idle... after all, that is it's i ntended purpose anyway, to sit idle until needed.

In fact pumped and battery storage make perfect sense. You get back roughly 80% of the power you store, and if you have a cheap base-lime source (as n uclear power is claimed to be, by nuclear enthusiasts) it would make sense to use that to charge the storage when demand was low.

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Bill Sloman, Sydney
Reply to
Bill Sloman

That's surprising to me and I know a lot of others.

How much would you make on a day when it is actually raining? I'm sure it is a lot darker then.

What is your max production?

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  Rick C. 

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Rick C

t is a lot darker then.

Scattered light is just as effective as direct sunlight. Some of the light scattered by clouds is reflected back into space, but it takes thick layers of cloud to reflect a lot of the incident light back into space - most of it gets scattered onto adjacent water droplets. Rain is less effective at s cattering light than lots of smaller water droplets, but cloud thick enough to let the smaller droplets merge into raindrops tends to be pretty thick.

Clouds don't actually absorb visible light.

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Bill Sloman, Sydney
Reply to
Bill Sloman

This is just the situation in France with high nuclear penetration. During weekends when consumption is lower, some nuclears are throttled back or even stopped for the weekends.

Temperature variation will cause stress to tubing, so you rally try to avoid rapid power level changes.

Reply to
upsidedown

Thermal cycling is bad for any thermal plant, but is more important for nukes because of the difficulty of replacing parts of the plant.

But you knew that.

Reply to
Tom Gardner

one of the problems with throttling is that the normal reaction produces isotopes that that produce isotopes that absorb neutrons. this is, called "poisoning" so you need to be producing enough neutrons when theese poisons pop-up to sustain a reaction else the chain reaction falls over and you have to wait for the poison to decay before it can be re-started.

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Reply to
Jasen Betts

How do they avoid Xe135 poisoning?

I've read that they do throttle nukes, but they don't explain how to avoid the poisoning problem. They also don't address the cost issue. Are electricity costs high in France?

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  Rick C. 

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Rick C

** On a dark cloudy to overcast day, the visible light level is only 1% to 5% of that on a sunny one - as anyone with a Lux meter can verify.

So the current output from a PV cell ought to vary in a similar way.

.... Phil

Reply to
Phil Allison

The type of scattering depends on the cloud particle size vs. wavelength. In backscatter, the light is scattered upwards to the sky, in isotropic scattering half of the scattering is scattered above horizon. Only forward scatter from large particles will scatter predominantly downwards.

Looking out from an aircraft window above the clouds, looking downwards towards the clouds, the clouds are extremely bright. That light scattered from the clouds will never reach the solar panels on the ground.

When the plane descends through the clouds, one should expect that it would also be very bright inside the cloud due to the forward and the down and side part of the isotropic scatter.

However, this doesn't match my observations.

Also looking at the MPPT controller of a solar panel, the operating point varies constantly with say 2/8 to 6/8 cloudiness, when cloud comes and goes. Clearly when even a small cloud comes between the sun and panel, the output will drop.

With a geographically spread out solar farm, only part of the panels are shadowed by the clod, thus the total farm output doesn't vary too much. But still it would be interesting to compare the output at 0/8 an 8/8 cloudiness.

If clouds would absorb a lot of light, it would heat up and re-evaporate the cloud particles. Some light morning clouds disappear before noon. Is this due to direct solar radiation absorbed in the cloud or due to heated up ground, sending out long wave IR captured by atmospheric H2O is an other matter.

Reply to
upsidedown

snipped-for-privacy@downunder.com wrote in news: snipped-for-privacy@4ax.com:

Yeah, clods like you should probably avoid high tech solutions like solar panels. A big turd like you casts a big shadow and the downwind stench must be damn near deadly.

Reply to
DecadentLinuxUserNumeroUno

Our enphase micro-inverter system is pretty efficient.

Yes, it can drop down, but always makes something.

This time of year with the sun angles, absolute max, with super-clear sky, is 55kWh. Best ever, 63kWh. The maximum power level from our roof's 34 panels is 8.5kW, limited by a 250W micro-inverter on each panel.

We make 10 to 12MWh per year. Right now our netmeter reading is about -1000 kWh. Saving up for the winter.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

0.123 Euros/kWh for the day rate and 0.087 Euro/kWh for the night rate.

Jeroen Belleman

Reply to
Jeroen Belleman

I wonder how the new EPR reactor will impact that? More than triple the es timated cost and quadrupled schedule. Do you think they will continue to s ell these reactors?

I'm willing to bet they don't load follow with these.

I still haven't found how nukes avoid Xe135 poisoning when load following. Maybe it's a very, very slow load following. Xe135 has a half life of som e 6 or so hours as does the precursor I135. That means when you throttle b ack the Xe killing neutrons fall back, but the production of more Xe135 doe sn't for hours allowing Xe135 to increase and absorb more neutrons than is desirable. Cut back too quickly and you can't bring the reactor back up fo r hours until the Xe135 decays.

Maybe they have a way of maintaining neutron production even as the energy output is reduced? I have no idea how they would accomplish that. Or mayb e the load following is just very shallow. I thought I read about at least one reactor that could be cut far back, maybe to 30% without poisoning.

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  Rick C. 

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Reply to
Rick C

Power is regulated by raising or lowering the control rods, and by manipulating the concentration of boric acid in the primary circuit water. The problem is that raising the control rods exposes a region of the core that is relatively less poisoned by Xe135, and which therefore risks being overly reactive. This is controlled by positioning fractional-height control rods.

I haven't yet found much about the typical range of the output power regulation. I guess it isn't a lot. Typical time constants are a few minutes.

Jeroen Belleman

Reply to
Jeroen Belleman

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