Energy From Thorium Discussion Forum

It is currently Oct 23, 2017 3:39 pm

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 55 posts ]  Go to page 1, 2, 3, 4  Next
Author Message
PostPosted: Aug 06, 2014 7:48 am 
Offline
User avatar

Joined: May 24, 2009 4:42 am
Posts: 826
Location: Calgary, Alberta
I recently saw this graphic, many of you have. The question, what would we need to deal with the challenge of the 2020 curve?
Attachment:
CalISO Duck Curve.png
CalISO Duck Curve.png [ 71.5 KiB | Viewed 2360 times ]


Top
 Profile  
 
PostPosted: Aug 06, 2014 10:20 am 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
Wow! Best evidence against the stupid idea of grid connected solar panels ive seen in months. California, stop subsidizing energy sources that deliver power right when it isnt needed.


Top
 Profile  
 
PostPosted: Aug 06, 2014 11:28 am 
Offline

Joined: Dec 24, 2011 12:43 pm
Posts: 219
Location: Newport Beach, CA
Cyril R wrote:
Wow! Best evidence against the stupid idea of grid connected solar panels ive seen in months. California, stop subsidizing energy sources that deliver power right when it isnt needed.


It actually looks like grid connected solar was helping smooth the load out until about mid 2013. The later evening peak is a secular trend. Maybe power plant workers will just idle the generators and take a siesta when its muy caliente.


Top
 Profile  
 
PostPosted: Aug 06, 2014 1:05 pm 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
Cthorm wrote:
Cyril R wrote:
Wow! Best evidence against the stupid idea of grid connected solar panels ive seen in months. California, stop subsidizing energy sources that deliver power right when it isnt needed.


It actually looks like grid connected solar was helping smooth the load out until about mid 2013. The later evening peak is a secular trend. Maybe power plant workers will just idle the generators and take a siesta when its muy caliente.


The irony is that Cali's crazy pricing and other energy policies are a major factor in this midday dip. They've actually got an active energy policy to hurt solar PV growth.

All these things are possible, in a world inhabitated by clichéd muscle boys, girls in bikinis, and governed by movie stars.


Top
 Profile  
 
PostPosted: Aug 06, 2014 2:44 pm 
Offline
User avatar

Joined: May 24, 2009 4:42 am
Posts: 826
Location: Calgary, Alberta
So to help guide the discussion, if you analyse the 2020 curve, and assume 9.5 GWe base load from other generators with the balance having to swing up and down, you get to a load factor of about 54% on the swinging plant if the minimum load is 15% of nameplate base load.

Keeping to round numbers the power conversion plant is about 2x the capacity of base load and the salt storage required runs to tens of thousands of tonnes for a 2 GWe peak electric on a 1 GWe base. This would not be a cheap endeavor.

The 15% minimum load is based on what should be possible for a steam turbine while keeping it on line. Why do you want it on line? Whatever PCU is used, you want it on line to be able to sell frequency regulating and spinning reserve to the ISO, because the system will need lots and lots of reserve to cope with the variation and the ramp rates in the evening.

The next questions are what sort of cost increase will that load following storage design look like and what sort of market price variation would be required to pay for that service?


Top
 Profile  
 
PostPosted: Aug 06, 2014 3:31 pm 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
The best candidate is probably the thermocline binary nitrate eutectic salt system that we discussed some years ago.

http://infohouse.p2ric.org/ref/22/21032.pdf

The cost of the system is $20/kWh thermal. With a molten salt reactor steam turbine you'd get about 3x the delta T so you cut the cost to 1/3 (almost, tank cost is slightly higher for higher temperature). If the system is upscaled it might be cheaper even. Perhaps an optimized system would be running at just $5/kWh thermal.

On steam turbine minimum load, many nuclear reactor vendors are claiming to be able to operate on isolated, island mode operation without turbine trip. ESBWR claims this, and the house load, even at full power, is only 80 MWe out of the 1600 MWe gross turbine rating, and it would be a small fraction for island mode support. So it looks like these turbines (big slow saturated steam turbines) can operate at <5% load. How do you think they do this? Is this only possible with 1800 rpm saturated steam turbines or can we make it work on modern superheat steam or even SCW turbines?


Top
 Profile  
 
PostPosted: Aug 06, 2014 5:14 pm 
Offline

Joined: Jun 19, 2013 11:49 am
Posts: 1497
They probably just accept low efficiencies compared to full load operation.


Top
 Profile  
 
PostPosted: Aug 07, 2014 12:39 am 
Offline
User avatar

Joined: May 24, 2009 4:42 am
Posts: 826
Location: Calgary, Alberta
Cyril R wrote:
On steam turbine minimum load, many nuclear reactor vendors are claiming to be able to operate on isolated, island mode operation without turbine trip. ESBWR claims this, and the house load, even at full power, is only 80 MWe out of the 1600 MWe gross turbine rating, and it would be a small fraction for island mode support. So it looks like these turbines (big slow saturated steam turbines) can operate at <5% load. How do you think they do this? Is this only possible with 1800 rpm saturated steam turbines or can we make it work on modern superheat steam or even SCW turbines?
All good questions; in some ways the saturated steam turbines may have an advantage here, they can probably tolerate a lower minimum load, but they would not be able to ramp as quickly from that low load condition. The driver is as follows: as steam turbines reduce load the last two stages of blades do a lot more churning than they do expanding which initially increases the dryness fraction, but eventually the local steam conditions go superheated and overheats the back end of the machine potentially allowing those same last stage blades to contact the stator. For fossil units running high steam temperatures, you get there a little sooner. But the fossil units have this advantage that provided the steam inlet temperatures can be held constant, they can be loaded quite quickly with few ill effects.

One steam turbine reference that I have talks about 10% minimum continuous load being possible for fossil units as if it is possible, but not common. The difficulty here is that the boiler is usually far less flexible than the turbine, so I'm picking that 10% is the minimum continuous load for for a fossil/high temperature STG designed with low load operation in mind. And we do want that high temperature for efficiency reasons. My best guess is that from 15% you can load aggressively, but at 10% there is a temperature transition that has to be dealt with, limiting the early ramp rate from 10%. Getting to 50% or 60% from 10% should be fine, but then there would be some catching up to do on the thermal equilibrium front, before pushing on.

As a foot note I would be extremely surprised if ESBWR can trip to house load, possible on paper perhaps, but for real equipment that is an extreme transition, and very few plants can do it. If running at low load already it might survive the transition, but from full load I would be very doubtful, and it is that full load to house load transition that you would like it to do in extreme situations. (I have a fix for that BTW, but won't discuss it here)


Top
 Profile  
 
PostPosted: Aug 07, 2014 1:37 am 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
Well, so far the ESBWR is a paper design. But it quite clearly states the capability to operate down to house loads upon loss of grid, with neither turbine trip nor reactor scram. They also claim 110% bypass capacity to the condenser so maybe that is what makes it possible? The reactor seems quite plausible since it has extra systems like isolation condensers, high capacity feedwater system with large feedwater reserves, loads of bypass valves and relief valves...


Top
 Profile  
 
PostPosted: Aug 07, 2014 7:58 am 
Offline

Joined: Jun 19, 2013 11:49 am
Posts: 1497
Wouldn't you have a giant resistor bank in the switchyard so you can dump power overboard while you throttle down?


Top
 Profile  
 
PostPosted: Aug 07, 2014 9:52 am 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
E Ireland wrote:
Wouldn't you have a giant resistor bank in the switchyard so you can dump power overboard while you throttle down?


That seems like a good thing to have, but ESBWR design documents don't mention that.

Also, if you generator problems, and have to trip the generator, you have to trip the turbine too and still need to bypass the steam somewhere. So I think you will want some kind of steam bypass option. Lindsay, isn't this a bit bad on the condenser, punnishing a vacuum low temperature condenser with high pressure high temperature steam?


Top
 Profile  
 
PostPosted: Aug 07, 2014 11:08 am 
Offline

Joined: Dec 24, 2011 12:43 pm
Posts: 219
Location: Newport Beach, CA
It seems to me the sensible thing to do in California is top operate your plant at full power constantly and divert heat from turbines to desalination when loads are low. But this would require the state to pay some sensible price for water instead of our constant shortages from our dysfunctional market.


Top
 Profile  
 
PostPosted: Aug 07, 2014 11:40 am 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
Cthorm wrote:
It seems to me the sensible thing to do in California is top operate your plant at full power constantly and divert heat from turbines to desalination when loads are low. But this would require the state to pay some sensible price for water instead of our constant shortages from our dysfunctional market.


Electricity is more valuable and in greater demand than desal water.

More important is probably the burdensome regulatory environment. California has a reputation of a hostile industrial business environment. The Calif lawmakers would have to throw out a big bone (subsidy/very favorable tax laws etc.) to get over that speed bump.


Top
 Profile  
 
PostPosted: Aug 07, 2014 1:19 pm 
Offline

Joined: Dec 24, 2011 12:43 pm
Posts: 219
Location: Newport Beach, CA
Cyril R wrote:
Cthorm wrote:
It seems to me the sensible thing to do in California is top operate your plant at full power constantly and divert heat from turbines to desalination when loads are low. But this would require the state to pay some sensible price for water instead of our constant shortages from our dysfunctional market.


Electricity is more valuable and in greater demand than desal water.

More important is probably the burdensome regulatory environment. California has a reputation of a hostile industrial business environment. The Calif lawmakers would have to throw out a big bone (subsidy/very favorable tax laws etc.) to get over that speed bump.



California actually has a moratorium on new nuclear power plants, which automatically expires if the nuclear fuel cycle is closed in the US (i.e. Yucca Mountain opens or fuel reprocessing is allowed). But it does have a couple of relevant loopholes:

1) It only applies to land-based nuclear reactors
2) It only applies to nuclear reactors that are producing electricity

So it'd be perfectly legal to build a new reactor solely for desalination or process heat. It'd also be legal to build a floating reactor for power generation. There is little hope of getting major funds from the state, but it's conceivable to get Federal or private funds to build a demonstration reactor, it just can't produce electricity...unless it's fueled by waste.


Top
 Profile  
 
PostPosted: Aug 07, 2014 1:54 pm 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5058
I wouldn't bet my money on those loopholes. When it comes to court, antagonists will claim, rightfully, that a desal or floating reactor makes as much long lived waste as a power reactor, on a thermal power basis.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 55 posts ]  Go to page 1, 2, 3, 4  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group