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
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
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
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
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