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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Frances M. Cleveland
* Xanthus Consulting International
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Ave
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338-3175
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