OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

emix message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


Subject: RE: FW: [emix] Power storage strategies


Frances and Gale

 

I also apologize for keeping this thread going … and going.  But it is a very good discussion.

 

On the issue of two-way communications I believe we have agreement on the need.  I believe we are still debating about the information to be communicated ( Transactional Energy priced offers and transactions versus REC-VEN device parameters and control signals ).  More on this below.

 

On the issue of tightly-coupled vs. loosely-coupled control, I believe we all agree that tightly-coupled control between the end device (load, storage or generator device) and its immediate controller is needed.  I believe we still have a debate about the meaning of loosely-coupled control.  In fact I would prefer the term loosely-coupled interaction, at least for Transactional Energy.

 

In the REC-VEN model, device discovery is required to allow the REC at all levels to apply control signals.  Discovery of end devices by their immediate controller I believe that automate discovery of end devices by their immediate controller is useful but not a requirement in the Transactional Energy model.

 

Gale states that reliability in the REC-VEN model is enhanced by reporting upstream the capabilities of all devices.  He suggests that this can be done in a simple way with a generic set of parameters to describe aggregated devices  (VENs) to higher level RECs.  In practice this may be difficult, but we shall see.  I assume that the parameters would include cost parameters such as fuel and variable operating costs, but I have not seen that mentioned in the REC-VEN EPRI paper.

 

In Transactional Energy the system capabilities are discovered by offers made and offers accepted (including option offers) at many points in time ahead of delivery.  Control is not necessary as the needs and capabilities of all of the parties are coordinated through priced offers and transactions.

 

Francis suggests that "the market would flail and be prone to gaming if the utility has very limited idea of who can do what".  The incentives for gaming markets are reduced by the Transactional Energy model which increases competition by dynamically priced offers to loads, DER and generators.  In today's market, competition is typically among only a few generators and perhaps one load serving entity who all may possess some market power.  The forward transactions provided in Transactional Energy also reduce incentives for gaming by limited the transaction sizes exposed to potential market power at real-time.  I am not sure what it means for a market to fail, but real-time price volatility from changes in wind and solar generation and grid conditions is the signal to loads and other generation that will help to rapidly balance the grid.  And by using forward transactions all parties can hedge their exposure to real-time prices and stability is further enhanced.

 

Frances suggests a need for assurance to the ISO/RTO from DER storage devices that they will follow through.  In the Transactional Energy model that assurance is provided by the imbalance costs they will pay for non performance in a transaction.  This is the same assurance provided by large generators in current ISO/RTO markets.  There is really not much more the ISO/RTO can do since it is the owner of the generator that has tight control over his device.  The ISO/RTO also has access to virtually instantaneous meter data from large generators so it can take action if a generator is not performing.  Such metering could be provided for DER, but except for very large resources, instantaneous metering at the distribution and transmission level grid of the net of DER and load will likely be more than adequate.  Such grid metering and will avoid the expense of low latency, higher bandwidth communications to millions of devices.

 

Francis says "But what Transactional Energy leaves out is the mechanism for the "utility/ESP" to determine what price to set for what, which is partially determined by knowing what capabilities are out there"

 

Transactional Energy does not specify a way to set the price.  Instead it facilitates interactions among parties to "discover" a price that is acceptable to both the buyer and seller.  A regulated monopoly utility can set a retail price, but generally that is done based on cost-of-service rates to retail customers as approved by a regulator.  Forward wholesale prices are discovered by negotiations based on priced wholesale offers made as in Transactional Energy.  ISOs and RTOs strive to use parameters as well as priced offers to control the large generators, but the complexity is immense and parameterization  for control of cascaded hydro dams, pumped hydro, and combined cycle generators has proved to be challenging.  In an open market there is little incentive for retail customers, generators, and storage devices to fully reveal the parameters describing their devices including their costs so that counterparties including ISOs and RTOs can extract more profit from them at their expense.  The back and forth of priced offers, rejections, counter offers and acceptances in Transactional Energy provides the information needed for market efficiency and the motivation for parties to cooperate.

 

Ed

 

Edward G. Cazalet, Ph.D.

101 First Street, Suite 552

Los Altos, CA 94022

650-949-5274

cell: 408-621-2772

ed@cazalet.com

www.cazalet.com

 

From: Frances Cleveland [mailto:fcleve@xanthus-consulting.com]
Sent: Wednesday, May 05, 2010 11:51 AM
To: Horst, Gale; Ed Cazalet; David RR Webber (XML)
Cc: emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies

 

Gale -

I think we in agreement on the concepts and configurations, just using some slightly different words.

Frances


At 11:05 AM 5/5/2010, Horst, Gale wrote:

I apologize for keeping this thread going … and going …. 
 
But wanted to illustrate how these two concepts relate (or are the same with different descriptions).  You could also implement the system, illustrated in the diagram Frances forwarded, in one or more other ways as shown in the REC-VEN graphic I attached.  The resources (or end nodes) controlled by one Resource Energy Coordinator (REC) could change over time (update the battery, PV capacity, or add additional resources etc).  The REC would update its operational parameters up to the Grid/Utility.  Of course, as Frances noted, this does require two-way communication from the REC (or tightly coupled controller) up to the Grid/Utility.
 
Frances, your diagram was a good example and I hope we are still on the same train of thought with my addition to the diagram? 
 
Thanks,
Gale
 
20b9c59b.jpg
 
 

Gale R. Horst

Electric Power Research Institute (EPRI)
942 Corridor Park Blvd.
Knoxville, TN 37932
Office: 865-218-8078
Cell:   865-368-2603

ghorst@epri.com


From: Frances Cleveland [mailto:fcleve@xanthus-consulting.com]
Sent: Wednesday, May 05, 2010 1:15 PM
To: Horst, Gale; Ed Cazalet; David RR Webber (XML)
Cc: emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies
 
Gale -

I think we are on a similar track. The key is the fact that most implementations will use some version of a multi-tiered configuration. See my diagram.

Frances

20b9c6b4.jpg

At 05:54 AM 5/5/2010, Horst, Gale wrote:

Frances:
 
Thank you for jumping in with more information and comments.  I think we are on the same track for the most part.  But I have a few clarifications / questions if you don’t mind? 
 

  • Two-way is also needed for any sort of a discovery process as well as being able to update the operational parameters.  The bottom line is that to meet all the goals of a smart system, we need two-way communications.  Out at the end node we can still accommodate simpler devices. But they would be under the control of an aggregating system or device that does communicate two-way (e.g. the REC as described in the REC-VEN concept in the EPRI whitepaper)
  • Your note about  “… determined by knowing what capabilities are out there” seems very much in sync with the concepts discussed in SG development areas.  Me must know what capabilities exist.  But my point is that you can know the capabilities without necessarily knowing or directly controlling the specific hardware providing these capabilites.  It is these capabilities that need to be reported up-stream where the decisions, markets, and “controls” originate. If this is done correctly, to another point you made, the utility has a very accurate idea of who can do what, when, how long etc.   The assurances can be designed into the system and achieve a higher level of reliability than we have today.
  • Perhaps there remains an assumption carried forward from DLC that without direct control the resource is not reliable.  If we can overcome this barrier, we open the door to an effective architecture that provides the same reliability with much lower cost and much better scalability. I’m wondering if we can make a list of the information and assurances we need to know, ones we may assume can only be obtained in a tightly coupled system?  This would define the system operations parameters or discovery parameters needed to provide what is needed. 
  • If the capabilities are known and and can be updated within the system design we not only enable the markets and reliability you described, but also scalability and long term maintainability. 

 
Thanks again
 

Gale R. Horst

Electric Power Research Institute (EPRI)
942 Corridor Park Blvd.
Knoxville, TN 37932
Office: 865-218-8078
Cell:   865-368-2603

ghorst@epri.com


From: Frances Cleveland [mailto:fcleve@xanthus-consulting.com]
Sent: Tuesday, May 04, 2010 7:52 PM
To: Ed Cazalet; Horst, Gale; 'David RR Webber (XML)'
Cc: emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies
 
Ed and Gale -

There will always be two types of control: direct, tightly coupled controls, and market-based, loosely coupled controls, depending upon the capabilities and the contracts.. But what Transactional Energy leaves out is the mechanism for the "utility/ESP" to determine what price to set for what, which is partially determined by knowing what capabilities are out there

This feedback may not be "tightly-coupled" in the sense of moment-by-moment as ISO/RTOs do, but the market would flail and be prone to gaming if the utility has very limited idea of who can do what. You could say that the storage owner would bid into the market, but what assurance does the utility have that they would really follow through? Yes, they would be penalized during the following month's bill, but that would not solve the utility's need within the next few minutes.

So my basic contention is that there MUST be two-way communications, although most interactions would be to send out DR signals. However, the utility needs to be able to get more up-to-date information in order to perform short-term planning (hour ahead, day ahead).

Frances


At 03:15 PM 5/4/2010, Ed Cazalet wrote:

Gale,
 
If I am managing a building with storage,  or I am the operating a  fleet of batteries I will need to know the capabilities of the batteries I have under my control, how their performance has degraded,  current max charge rate and discharge rate, round trip efficiency, current temperature, cost of cycling, and much more.  A discovery mechanism as you suggest can be useful to me. 
 
However, I can offer to buy and sell energy to other parties using the storage by making offers to accept energy in one set of time intervals and return it in another set of intervals for a price.  It is up to me to manage the state of charge of the batteries, the temperature, and the battery cycling by the offers I make or accept with counterparties.  The interface with the customer can be called the 'plane of control' or Energy Services Interface' .
 
As you say the question of who is authorized to use or control the storage is related to the plane of control of the device.  The idea behind Transactional Energy is to push the control as close as possible to the device and then use priced offers and transactions to interact with other systems including markets.  This simplifies and standardizes the interfaces among the systems and hides the complexity of the devices behind the control interface.  The buyers and sellers don't need to know if the building is providing storage services, by making ice, shifting load, using batteries, or local generation.
 
Ed
 
Edward G. Cazalet, Ph.D.
101 First Street, Suite 552
Los Altos, CA 94022
650-949-5274
cell: 408-621-2772
ed@cazalet.com
www.cazalet.com
 
From: Horst, Gale [mailto:ghorst@epri.com]
Sent: Tuesday, May 04, 2010 2:21 PM
To: Ed Cazalet; David RR Webber (XML)
Cc: fcleve@xanthus-consulting.com; emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies
 
Ed,
 
I’m not sure I fully understand the follow up question abut the plane of control.  Perhaps an example will do.  If I have a storage battery of a given capacity and other characteristics, we should consider the questions:
 
-        What if the battery capabilities degrade over time?  A year from now it would NOT be able to provide the services it is assumed to be capable of because of a fixed commissioning mechanism.  Some dynamic operational parameters or discovery parameters that could be re-involked would solve this.
-        What if the battery is upgraded / replaced or another electricity storage mechanism is put in it’s place?  Until the up-stream system knows this, it would be under-utilized.  Again, dynamic operational parameters or discovery parameters along with an up-stream system capable of calculating the new parameters into the system operational algorithm will make this type of change a simple everyday process accommodated by design.
-        Perhaps the ownership and plane of control is a different but related question about who is authorized to utilize the services of the storage device?  In my thinking this could be different for every system depending on the localization and abstraction of the architecture.
 
Not sure if I answered the question….
Gale
 
 

Gale R. Horst

Electric Power Research Institute (EPRI)
942 Corridor Park Blvd.
Knoxville, TN 37932
Office: 865-218-8078
Cell:   865-368-2603

ghorst@epri.com


From: Ed Cazalet [mailto:ed@cazalet.com]
Sent: Saturday, May 01, 2010 11:34 AM
To: Horst, Gale; 'David RR Webber (XML)'
Cc: fcleve@xanthus-consulting.com; emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies
 
Gale,
 
I have added your statement in your recent email to the power storage strategies thread below.
 
You said:
 
I missed the call/discussion this week.  But wanted to note that the system intelligence must be able to self discover and modify in some fashion as what David Webber described.  When dealing with resources that can either degrade or be upgraded/enhanced over time, we have to have an automatic adjusting mechanism which is very similar to a discovery mechanism.  Otherwise the system resources will either become underutilized or over committed over time.
 
 
Are you advocating a discovery mechanism (1) within the plane of control / single ownership boundary or (2) more globally in place of loose coupling, market-based interactions outside the owner's boundary?
 
Ed
 
Edward G. Cazalet, Ph.D.
101 First Street, Suite 552
Los Altos, CA 94022
650-949-5274
cell: 408-621-2772
ed@cazalet.com
www.cazalet.com
 
From: Holmberg, David [mailto:david.holmberg@nist.gov]
Sent: Tuesday, April 27, 2010 1:31 PM
To: David RR Webber (XML); Ed Cazalet
Cc: fcleve@xanthus-consulting.com; 'Phil Davis'; Toby.Considine@gmail.com; emix@lists.oasis-open.org; 'Considine,Toby (Campus Services IT)'
Subject: RE: FW: [emix] Power storage strategies
 
I would add to that­even in the local scenario (i.e., within single ownership boundary) a market based model can make sense. I still need some value signal to determine balance of load, storage, and generation. Price and markets allow for more distributed and simple control. Of course, once we look at interactions with entities outside the owner’s boundary (call it the ESI), we want loose coupling, market-based interactions.
 
Thanks for a great discussion,
David
 
From: David RR Webber (XML) [mailto:david@drrw.info]
Sent: Tuesday, April 27, 2010 4:04 PM
To: Ed Cazalet
Cc: fcleve@xanthus-consulting.com; 'Phil Davis'; Toby.Considine@gmail.com; emix@lists.oasis-open.org; 'Considine,Toby (Campus Services IT)'
Subject: RE: FW: [emix] Power storage strategies
 
Ed,
 
Yikes!!! I was not expecting that answer!  I just fell into a time vortex back ten years to beginning of ebXML work.
 
My scenario was micro-economy local scenario - yours is macro economy - eMarketplace model. 
 
Obviously infinite permutations of these once the supporting infrastructure is there.
 
Very cool.  I like it!
 
Thanks, DW
-------- Original Message --------
Subject: RE: FW: [emix] Power storage strategies
From: "Ed Cazalet" <ed@cazalet.com>
Date: Tue, April 27, 2010 3:25 pm
To: "'David RR Webber (XML)'" <david@drrw.info>,
"'Considine,Toby (Campus Services IT)'" <Toby.Considine@unc.edu>
Cc: <fcleve@xanthus-consulting.com>, "'Phil Davis'" <pddcoo@gmail.com>,
<Toby.Considine@gmail.com>, <emix@lists.oasis-open.org>
To continue this excellent discussion.
 
First, for the benefit of Francis below is a link to White Paper on Transactional Energy that, in part, deals with ancillary services in a way that I think levels the field between generation, storage and loads as providers of ancillary services.  The idea is to facilitate energy transactions on shorter intervals including 4-second intervals for frequency regulation.
 
Download Document: 
http://www.oasis-open.org/committees/download.php/37464/Transactional%20Energy%20White%20Paper%20Draft%20007.pdf
 
 
With respect to David's quest for simplicity, I think we are closer than it might seem.
 
 
David wrote (italics) :
 
So my real time scenario would run something like this:
 
1) Power source queries grid for status of existing available storage devices with surplus capacity
 
2) From responses and my available power - I commit with a couple of them to push power to them
 
   - to determine this I just need ROM calculations that tell me they can absorb the power at the rate I'm generating it.
   - their availability should be immediate, or time when to commence charging
   - indicate status update refresh period for 20% change in stored power or full - depending on anticipated storage rate - this you can calculate - either from history of previous service to that device - or device itself can give you estimate - if you are off by a % it won't be a big deal.
 
3) Commence power distribution
 
4) Receive regular status updates from devices of their new storage level and remaining capacity.
 
5) Compute decision - continue power supply or loop back to 1)
 
6) If no storage devices available - then scale back power generation - until receive storage notification from device available.
 
 
My revision.
1)  Power source queries storage providers or brokers for quotes to store (buy) 25 MW per hour from 2 am to 5 am ( 100 MWh)
 
2) Generator accepts the best quote of $25 per MWh.
 
3) Generator requests quote to store another 100 MWh for the same hours.
 
4) Storage providers are full and provide no further quotes.
 
5) Generator scales back generation to store only 100 MWh.
 
Note your example talked about where the power was stored and not what the generator got back ( money or energy) and when.  My example assumes the generator gets money for the stored energy.
 
Perhaps a better transaction with storage is as follows:  Generator requests a quote for storing 100 MWh from 2 am to 6 am and drawing 80 MWh from 2 pm to 6 pm, ( accounting for a rough 80% round trip storage efficiency).
The storage provider might quote $50 per MWh stored for this service. 
 
Ed
 
Edward G. Cazalet, Ph.D.
101 First Street, Suite 552
Los Altos, CA 94022
650-949-5274
cell: 408-621-2772
ed@cazalet.com
www.cazalet.com
 
From: David RR Webber (XML) [mailto:david@drrw.info]
Sent: Tuesday, April 27, 2010 8:02 AM
To: Considine,Toby (Campus Services IT)
Cc: fcleve@xanthus-consulting.com; Phil Davis; Toby.Considine@gmail.com; emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies
 
All,
 
I'm still urging for keeping this really simple!
 
From the perspective of the supplier for the surplus power to push to the storage device - how much precision do you really need!?!?  Frankly I really don't need to know much about the device beyond how much capacity to a ROM (Rough Order of Magnitude).  Why over engineer this - if you can use simple tracking messages to see how you are progressing?  Remember when a 5Mb hard drive was a big deal?!  Expect market to drive demand for low cost buckets of storage in future...
 
So my real time scenario would run something like this:
 
1) Power source queries grid for status of existing available storage devices with surplus capacity
 
2) From responses and my available power - I commit with a couple of them to push power to them
 
   - to determine this I just need ROM calculations that tell me they can absorb the power at the rate I'm generating it.
   - their availability should be immediate, or time when to commence charging
   - indicate status update refresh period for 20% change in stored power or full - depending on anticipated storage rate - this you can calculate - either from history of previous service to that device - or device itself can give you estimate - if you are off by a % it won't be a big deal.
 
3) Commence power distribution
 
4) Receive regular status updates from devices of their new storage level and remaining capacity.
 
5) Compute decision - continue power supply or loop back to 1)
 
6) If no storage devices available - then scale back power generation - until receive storage notification from device available.
 
What I would anticipate is that scenario 6) is really about always having enough storage capacity available to balance demand. 
 
From our XML perspective - so long as our simple message designs contain enough information to drive the decision making - we don't need more.  E.g. we want minimalistic message design.  People will always think of more and more exotic information that can be added - we want to strongly resist that - and require ONLY the information needed to drive a working process - nothing more.  Remember - the messages do NOT need to contain information that can be obtained elsewhere.  Otherwise you end up with a standard that is extremely tough to implement - and then even worse to have consistent interoperability across vendors.  Plus break the messaging down into small discreet purposes.  For example - I do NOT need to send device profile but once - first time device is available.
 
DW
 
 
 
 
 
Thanks, DW
-------- Original Message --------
Subject: RE: FW: [emix] Power storage strategies
From: "Considine, Toby (Campus Services IT)" <Toby.Considine@unc.edu>
Date: Tue, April 27, 2010 9:44 am
To: Phil Davis <pddcoo@gmail.com>, "Toby.Considine@gmail.com"
<Toby.Considine@gmail.com>, "emix@lists.oasis-open.org"
<emix@lists.oasis-open.org>
Cc: "fcleve@xanthus-consulting.com" <fcleve@xanthus-consulting.com>
Well, I think you are correct.
 
The discussion of the performance attributes or an offering that we skated around last month are really about ancillary services….
 
Time to respond after request?
Ramp time after response?
Minimum response
Maximum response
Maximum sustained response (define sustained)
Cycle time…
 
These are all aspects of being able to fit DR to ancillary markets, not just to “traditional” DR. As most of them are some sort of “meet or exceed” expectations, the same DR could be offered to different markets. Alternately, the building owner could easily see how system augmentation to improve a performance metric would allow the building to play in a more lucrative market…
 
tc
 
 


"If flies are allowed to vote, how meaningful would a poll on what to have for dinner be, and what would be on the menu?" -  Unknown


Toby Considine
Chair, OASIS oBIX Technical Committee
Co-Chair, OASIS Technical Advisory Board
Facilities Technology Office
University of North Carolina
Chapel Hill, NC
 
Email: Toby.Considine@ unc.edu
Phone: (919)962-9073
http://www.oasis-open.org
blog: www.NewDaedalus.com
 
 
From: Phil Davis [mailto:pddcoo@gmail.com]
Sent: Monday, April 26, 2010 9:10 PM
To: Toby.Considine@gmail.com; emix@lists.oasis-open.org
Cc: fcleve@xanthus-consulting.com
Subject: RE: FW: [emix] Power storage strategies
 
Frances is right of course.  John Kueck at Oak Ridge feels there will come a time that the demand side is the total resource for reliability and regulation.  Though I'm not sure of the 100% level, there are aspects of ancillary service participation that properly implemented and managed would (I think) be more appealing to commercial buildings than would traditional  DR programs.  I have been assuming, perhaps wrongly, that our discussions energy communications would include support of ancillary services.  Is this correct?
 
Thanks!
 
Phil
 


From: Toby Considine [mailto:tobyconsidine@gmail.com] On Behalf Of Toby Considine
Sent: Monday, April 26, 2010 3:35 PM
To: emix@lists.oasis-open.org
Cc: fcleve@xanthus-consulting.com
Subject: FW: FW: [emix] Power storage strategies
I forwarded this conversation to Frances Cleveland, who is working on electrical standards for storage management (the complicated process we are trying to stay out of). Thee followed back with a an interesting analogy of the more valuable types of response dictated by ramp time, response time, et al.
 
tc


"If something is not worth doing, it`s not worth doing well" - Peter Drucker


Toby Considine
TC9, Inc
OASIS Technical Advisory Board
TC Chair: oBIX & WS-Calendar
TC Editor: EMIX, EnergyInterop
 
Email: Toby.Considine@gmail.com
Phone: (919)619-2104
http://www.tcnine.com/
blog: www.NewDaedalus.com
 
 
From: Frances Cleveland [mailto:fcleve@xanthus-consulting.com]
Sent: Monday, April 26, 2010 3:06 PM
To: Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: Re: FW: [emix] Power storage strategies
 
Toby -
Just to add to the mix, I did not see "ancillary services" in this discussion - these are services like var management, frequency deviation mitigation, load following, etc. These are huge issues for utilities, and just like derivatives are often more "valuable" than stocks in the stock market, are often of more value to the utility than just energy.
If I can't send this directly to the emix list, please forward .....
Frances

At 11:52 AM 4/26/2010, Toby Considine wrote:
Sharing the conversation that broke out today in EMIX…
 


"If something is not worth doing, it`s not worth doing well" - Peter Drucker


Toby Considine
TC9, Inc
OASIS Technical Advisory Board
TC Chair: oBIX & WS-Calendar
TC Editor: EMIX, EnergyInterop
 
Email: Toby.Considine@gmail.com
Phone: (919)619-2104
http://www.tcnine.com/
blog: www.NewDaedalus.com
 
 
From: Ed Cazalet [mailto:ed@cazalet.com]
Sent: Monday, April 26, 2010 2:50 PM
To: 'Phil Davis'; 'David RR Webber (XML)'; Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: RE: [emix] Power storage strategies
 
David,
 
Thanks for getting an informative debate going.
 
I assume that you are suggesting that storage can be generically modeled as a device with a MWH capacity, a power ratio for both charge and discharge of say 4 MW per MWH (4 to 1 ratio) and a current state of charge (% of the MWH energy capacity) with some updating of these parameters as necessary.
 
Further, I assume  you are suggesting that this information be used by other parties ( and possibly the owners )  to dispatch the storage.  However you have not mentioned how third parties would be charged or contract for the use of the storage.
 
Keeping with your idea to keep the storage model simple. we would need at least also specify a round trip efficiency of storage devices since this efficiency ( MWH Out / MWH in) can vary between 50% and over 90% for various storage technologies.  Additionally, some compressed air energy storage devices (CAES) also require natural gas as an input energy source in addition to electric energy. ( Note: round trip efficiency is also a function of state of charge and rate of charge and discharge, but let's say we ignore that for simplicity.)
 
A fixed power ratio is also problematic for many storage devices.  Many batteries have asymmetric charge and discharge ratios, so that we would need to specify different ratios for charging and discharging.  Additionally, many batteries are able to charge or discharge at high rates for short time periods or when they are not near full or not near empty and then at much lower rates on a sustained basis.
 
Another critical parameter is response ramp rate.  Some devices such as batteries and flywheels have an almost instant response whereas pumped hydro and CAES have a much slower response, limiting their value for frequency regulation.
 
Battery life is also an issue.  A battery typically might be able to discharge a fixed number of MWH over its life depending somewhat on how charging and discharging is done.  So charging and discharge for small economic benefit must be avoided to save the battery for situations where such use has high value.
 
What information we provide about storage also depends on what side of the plane of control (energy services interface) we might be on.  On the storage device side of the interface, the physical models that you suggest may be useful, however the need to over simplify is less.
 
On the inter domain side of the interface communicating even a simplified storage model to other parties and then figuring out how to dispatch that storage in coordination with generation and load is challenging.  US ISOs are currently working on tariffs and software to allow limited energy devices such as flywheels and batteries with 15 to 30 min of storage to participate in frequency regulation markets.  It is a significant software and market design challenge to recognize the limitations of storage (which vary by device type) in comparison to generation while at the same time given storage the benefit to the system of the much faster response of storage in providing regulation services.  And most have not yet fully implemented the economic dispatch of deeper storage devices into their economic dispatch and locational pricing models.
 
If avoiding over complication by engineers and striving for simplicity is a goal, then I recommend the pure simplicity of Transactional Energy outside of the plane of control of specific devices.  What is done inside the plane of control is another matter, where the specifics of each device are much easier to accommodate.
 
With Transactional Energy a storage owner can make or accept an offer to buy MWH at a given rate and at given low price at night or when the wind is blowing hard.  The amount and price will depend on many factors such those we have discussed above.  The storage owner can also make or accept an offer to sell energy at a higher price in the afternoon or when the wind is not blowing.  A party could perhaps simultaneously enter into a transaction to sell in the morning and buy in the afternoon from the storage owner.  This is real simplicity and it is the way we buy and sell almost everything else in our life..
 
Perhaps as both an economist and an engineer,  I can revise your statement " Never under estimate an engineer's ability to add complexity!
to say, "Never underestimate the ability of an economist's market to make simple what an engineer can make complex!"
 
Ed
 
 
Edward G. Cazalet, Ph.D.
101 First Street, Suite 552
Los Altos, CA 94022
650-949-5274
cell: 408-621-2772
ed@cazalet.com
www.cazalet.com
 
From: Phil Davis [mailto:pddcoo@gmail.com]
Sent: Monday, April 26, 2010 8:27 AM
To: 'David RR Webber (XML)'; Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: RE: [emix] Power storage strategies
 
Actually, GE announced such a system last week and is hiring 400 people in Atlanta to staff the new business. It's a substation level product.  Also, I have spoken personally with people at Hitachi and Samsung who are testing a 1 MW battery.  Such a battery from another vendor is in test operation behind PJM's main offices. So local here takes on a new meaning depending on whether it is truly behind the customer meter, or behind the distribution grid meters (substations and the like), or on a transmission system.  Theoretically, batteries of this size could replace generators used for voltage or frequency support.
 
Phil Davis
 

 

From: David RR Webber (XML) [mailto:david@drrw.info]
Sent: Monday, April 26, 2010 10:58 AM
To: Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: [emix] Power storage strategies
Toby,
 
It occurs to me that local storage can potentially play a role here - depending on its efficiency of course.  One can anticipate that future technology will offer higher % there - especially if market forces drive that equation.
 
Therefore - a future system could offset power surges by drawing on locally stored resources that were captured during off-peak or excess capacity.  In fact such a system may notify suppliers that they can "push" excess power to local storage at some pre-determined cost point - and of course also need to indicate that the storage facility is at a certain % level, or if empty - accept units at a higher cost rate.
 
DW
 
 
________________________________________________________________________
This email has been scanned for SPAM content and Viruses by the MessageLabs Email Security System.
________________________________________________________________________
--------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
 

******************************************
*     Frances M. Cleveland  
*    Xanthus Consulting International
*     369 Fairview Ave
*     Boulder Creek, CA 95006
*     Tel:  (831) 338-3175
*     Cell: (831) 229-1043
*     fcleve@xanthus-consulting.com
*     www.xanthus-consulting.com
******************************************
________________________________________________________________________
This email has been scanned for SPAM content and Viruses by the MessageLabs Email Security System.
________________________________________________________________________
--------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php

--------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php


******************************************
*     Frances M. Cleveland  
*    Xanthus Consulting International
*     369 Fairview Ave
*     Boulder Creek, CA 95006
*     Tel:  (831) 338-3175
*     Cell: (831) 229-1043
*     fcleve@xanthus-consulting.com
*     www.xanthus-consulting.com
******************************************



[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]