wind backup - flywheel energy storage vs STOR diesels

[dave andrews]

Many thanks Ted  (from Carbon Catalysts - many ex CEGB / National Power / Power Gen people) - does any one else know to what extent Dinorwic actually makes money out of day / night arbitrage?

 

Regards

 

Dave Andrews

On 18 August 2010 13:48, Edward East <edwar...@virgin.net> wrote:

Dave,

I cannot offer information on the economics of Dinorwic, other than to say that (if I recall correctly) about  25% of the energy input is lost in the system from conversion loss and fluid friction loss. That has to be taken into account in addition to the differences in pricing during a day.

I can shed some light (simplified) on other aspects of the dynamics of the Grid.

The system frequency target is normally set at 50.00 Hz. Frequency changes as the balance between demand and generation alters. The Grid controller attempts to balance the two by instructing the generators, but there is a range of frequencies between which no instructions will be issued, say 49.95 to 50.05 Hz.

All generators and synchronous machines that are connected to the Grid are locked in to the system frequency. If the demand increases, the frequency start to fall. There is only a relatively small amount of kinetic energy in the rotating parts of the generators so the governor system of the turbines driving the generators respond by very rapidly increasing the energy input to restore the balance. The characteristic of the governor can be varied to allow a small deviation from the target frequency rather than attempting to return to exactly 50.00 Hz which gives a more stable system.

With a gas turbine, the fuel input is adjusted very rapidly. With a steam turbine, the energy within the boiler provides a relatively large amount of stored energy and the fuel input to the boiler (or nuclear reactor heat output) is increased after a minute or two to restore the equilibrium. So the combination of some rotational kinetic energy and some potential energy stored in the boiler pressure parts gives some flywheel effect. National Grid Co. may be prepared to give estimates of the amount of kinetic energy in the system, as they do need to know that when making stability calculations for different scenarios.

The power required to drive a machine is proportional to its speed (depending on the machine characteristics). When the system frequency drops the power of most rotational machinery being driven will drop,  which also helps to stabilise the situation.

The opposite effects take place when demand falls.

In an AC system it is not desirable to allow voltages to vary more than a small amount with demand. Voltage variations are not a normal power control mechanism (they are a reactive power control mechanism, which is an very different matter) The generator and Grid system voltages are maintained within quite close limits, otherwise the system can become unstable and parts of it fall out of synchronism, with adverse consequences.

Voltages can be reduced deliberately at the final distribution stages of the system as the first stages of deliberate load reduction, and the system can also be deliberately run at a low frequency (down to 49.00 say) to reduce demand before having to cut customers off.  We have not seen such tactics deployed very much in recent decades, but it was a regular feature before the 1970s and we may well see it again in a decade or two.

The financial consequences for energy users will depend entirely on their individual circumstances. They are only paying for energy used but they may suffer from reduced product outputs or quality control problems. Only individuals can answer that.

The fundamentals of AC grid systems everywhere are the same so all will have very similar characteristics to ours provided that there is not a shortage of generating capacity to meet demand.


Regards,

Ted




So, when demand increases the frequency
dave andrews wrote:

Can any of the Carbon Catalysts offer anything here?  In particular, to what extent does Dinorwic make any money out of arbitrage between day and night pricing as opposed to STOR?

 

Thanks

 

Dave A

---------- Forwarded message ----------
From: Andrew Smith <clav...@londonanalytics.info>
Date: 18 August 2010 12:03
Subject: Re: wind backup - flywheel energy storage vs STOR diesels
To: energy-disc...@googlegroups.com


On this question of flywheels - I'd like to clarify something. Have I got the following reasoning right? If it's wrong, please do correct me.

1) On a grid, electricity supply has to balance the load at every given moment ...

2) ... give or take a tiny bit of electrical capacitance within the grid infrastructure.

3) When load increases, from an equilibrium situation, then what happens at first, before any plants can respond by increasing fuel throughput, is that grid frequency drops.

4) The frequency has dropped, because in order for supply and load to balance, the extra energy going to the load has come from somewhere: it has come from the rotational energy within the spinning turbines of thermal plants;

5) their rotation speed sets the grid frequency

6) they've slowed down a bit, and thus frequency drops; they slow, giving up some kinetic energy; this energy gets converted into electricity.

7) So what's happening, is that the turbines in this situation are behaving exactly like flywheels.

8) After the frequency drop, further potential gaps between supply and demand are met (if plant doesn't ramp up in time) by the network voltage dropping.

9) some loads reduce their power draw when the system voltage drops, resulting in demand reductions across the network.


If that's right, then I have three questions.

A) Are there any estimates of the total energy available in these turbines-as-flywheels, within the range of frequency fluctuations allowed?

B) Given the range of voltage drops we actually see across the network, what are the financial costs to energy users of those dips?

C) How do the frequency variations and voltage dips on our grid, compare with other grids in the (post-)industrial world?


Regards,
Andrew

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[dave andrews]

Yes but wouldn't they be earning more money just keeping the reservoirs full and bidding into say Frequency response - worth £60k/MW per year for just sitting there, which they wouldn't be able to do if they were messing about arbitraging, which on the back of a fag packet seems to earn a lot less?

On 18 August 2010 17:06, Ariel Bergmann <E.A.Be...@dundee.ac.uk> wrote:

Dave

It is likely that the Dinorwic has a profitable arbitrage margin on all regular work days, IF it is being run commercially for peak shaving. The wholesale price differential between day time peaking generation and night time off peak generation is greater then the round-trip loss in energy. Given the bilateral contracting for scheduled selling the power and purchasing the power, it is unlikely anyone will reveal the 'commercially sensitive' information on costs/revenues or profitability.  You can be sure that it is being operated to make a reasonable return on investment for the owners.

 

If anyone wants to see information on grid stability of frequency and balancing I recommend a visit to the NETA web site on network balancing, www.bmreports.com. This site gives large amounts near real time operational data of the grid.

 

regards

Ariel Bergmann

 

 

Dr. Ariel Bergmann

Lecturer in Energy Economics

Centre for Energy, Petroleum and Mineral Law & Policy (CEPMLP)
Univesity of Dundee

Carnegie Building

Dundee, Scotland, UK

DD1 4HN

Tel: 44 1382 384742 (O) / 44 0784 112 4611 (M)
Fax: 44 1382 385854
Email: e.a.be...@dundee.ac.uk 

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Website: www.CEPMLP.org

 

The University of Dundee is a Scottish Registered Charity, No. SC015096.

 

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Please consider the environment. Do you really need to print this email?

>>> dave andrews <uk.kolek...@gmail.com> 18/08/2010 13:56 >>>

The University of Dundee is a registered Scottish charity, No: SC015096

[dave andrews]

From: David Tolley <dltcon...@btinternet.com>
To: carbon-c...@googlegroups.com

Sent: Wednesday, 18 August, 2010 15:39:56
Subject: Re: carbon catalysts Fwd: wind backup - flywheel energy storage vs STOR diesels

THERE IS A USEFUL FILE WITH THIS TOO BIG TO GO THROUGH THE SYSTEM - APPLY TO dAVE tOLLEY DIRECTLY

Responding to Dave Andrews' email 
 
Dave
 
I have spent a little while looking for some public domain data I had but don't seem to be able to find it!  Your question is an interesting one but can't really be answered in the way you present it.  In the early days of the electricity market when Dinorwig was owned by National Grid they typically kept 2 units for arbitrage, 2 units spinning in air for short term reserve, and two units static for standing reserve; which fitted with the NGC contractual framework of the day.
 
With the advent of NETA and IP's ownership of the plant as part of a wider portfolio matters have become somewhat more sophisticated.  You can get an idea of what is going on from this interesting investor presentation of 2007.  If you look at slides 39 to 47 they illustrate how they use trading to add value to their anticipated generation output as timescales approach the day ahead stage.  Slides 89 to 98 show how at the day ahead stage they flip out of the arbitrage world and into the balancing and reserve markets.  Slides 108 and 109 illustrate a particular investment at Dinorwig that was intended to add to the overall value of these processes.
 
Somewhere I thought I had a much better picture of how this value optimisation evolves for the UK International Power portfolio as real time approaches; but I can't find it!!  I am not sure if any of this helps with the questions posed at the end of Andrew Smith's email.  It is all a matter of system inertia!
 
A - It should be possible to estimate the energy available at any instant in time and National Grid will hold a sufficiency of reserve dependent upon this estimate ... as enshrined in the SQSS
 
B - This reserve is there to stabilise frequency.  Voltage is another matter, and the costs more difficult to quantify I suspect
 
C - Observed frequency variations tend to be a function of the size of the system; UCTE is very stable, the Irish system fairly frisky!!
 
I doubt if any of this helps .... but it is all very interesting!!
 
David
 
 
David Tolley
DLT Consulting

+44 (0) 7989 493874
+44 (0) 1962 877329

[dave andrews]

Dave,
As Ted of Carbon Catalysts has given an excellent reply but I would like to
pick up on the 'quality of supply point' at the end of the query.  The
UK electricity supply like any other is subject to many disturbances
very few of which are due to the capability of generation or
transmission. Perhaps 95% of outages are occur on the distribution
system. The result is a supply with about 60 to 80 consumer minutes
lost per annum. In addition,surges and dips also occur frequently on
any network due to heavy currents which clear faults, lightning and
switching voltage spikes etc. The cost of these to customers depends on
the use being made of the power. There is a major industry providing
power quality conditioning and back up power.  However the quality of
the public supply without any additional quality measures is sufficient
for the majority of applications. I have investigated power quality issues
in quite a few countries and I have no doubt that the UK reliability and quality
is very good both from my site experience and published statistics.

Regards
Bernard Quigg

[dave andrews]

If I can add a bit more to the excellent piece from Ted of Carbon Catalysts and David Hirst

 

If frequency drops below that which the governor mechanism outlined below by Ted East can deal with, then the next thing that happens is for  all the large power users, such as steel works (are there any left)? cold stores and such like who have entered int a Frequency Service contract with NnGrid, and whose relay is armed, this relay instantaneously trips off the main power supply.

 

These relays are set at a range of settings so that as the hz falls, more and more load is tripped off until the frequency stabilises.  NG has about 2 GW ? of such load under contract and you can earn about £50/MW per year.

 

Such disconnections are contracted to be for no more than 20 minutes in the main - which is immaterial to a cold store, or melting furnace.

 

Simultaneously with these load disconnections, Ngrid also sends out a signal to all the participants in STOR - short term operating reserve and this is at least 500 kW of emergency diesels, plus sundry gas turbines, part loaded steam and so forth, and probably quite a lot of Dinorwic (which is why I doubt it earns much from arbitrage since STOR is much more lucrative).

 

The STOR participants are required to be up an running in a range from 5 - 20 minutes, and as soon as they are up, Ngrid turns the frequency relays back on, and re connects the loads.

 

The system is designed to be able to cope with the successive loss of two by 660 MW or one Sizewell.

 

The STOR diesels owned by Wessex Water appear to be used in this way about once er month.  N Grid could presumably do without this clever but complex system, but it would require a much greater proportion of part loaded steam cycle generators which is inefficient.

 

Note that diesels can compete very well with Dinorwic, even with their expensive fuel.

 

If that fails then there is automatic disconnection of pre selected sub stations as happened last year.

 

I see no reason why this system could not be extended by allowing domestic disconnection of high power circuits - say a 3 kW water heater in every home = 75 GW -and the bringing into commission of the existing 25 GW of other emergency diesels that are already sat there rusting away, already paid for which could earn money and be more reliable as a result.

 

Details here: http://www.claverton-energy.com/?dl_id=131

 

and here:

 

http://www.claverton-energy.com/commercial-opportunities-for-back-up-generation-and-load-reduction-via-national-grid-the-national-electricity-transmission-system-operator-netso-for-england-scotland-wales-and-offshore.html

 

Also see Wikiepdia article "control of National Grid"

http://en.wikipedia.org/wiki/Control_of_the_National_Grid

 

Dave Andrews

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[bernar...@aol.com]

Dave,
As you say frequency response services get in before STOR. Two points
- I think the annual value is about £50/kW - not per MW and
disconnecting water heaters was - and probably still is - used in what
was Johannesburg to disconnect domestic usually 3kW water heaters
across the city using an early version of ripple control on the mains.
I believe similar schemes existed in Switzerland. It seems that these
schemes worked best with municipalities where all the benefits of
delayed investment went to one outfit. Most housing in Johannesburg
did not have gas so taking out water heating was particularly
effective. In the UK, before the load shedding on selected substations
there is also a two stage voltage reduction scheme in the distribution
networks which can be deployed when time allows. It takes a minute or
two for each 3% stage.
Best Regards
Bernard Quigg

Regards

Dave Andrews

Dave,

Regards,

Ted

Thanks

Dave A

Regards,
Andrew

--

3 Victoria Place

[Chris Hodrien]

Dave, thanks for this useful clarification.

 

I presume that is '500 MW of emergency diesels' - care with units! (.....confirmed from Mark Duffield's Claverton article cited (- date =?).

 

Re. your claim: diesels can compete very well with Dinorwic, even with their expensive fuel" - clearly the existing contracted set of 500 MW'-worth is doing so, which is why they were contracted (if their bids were too high, NG would have rejected them in favour of supply-side or demand-reduction load balancing), but this does not** (underline 4 times!) imply that the rest of the 25-100 GW of available UK backup generator capacity would be equally so, otherwise why wasn't it bid/accepted?  Why have NG only accepted 500 MW of bids, and why have no (not much) more than 500 MW of owners bothered to bid at competitive rates? You know the real situation very well 'first-hand' from within Wessex Water, the cost of the interface gear and set-up manpower costs (both technical and commercial) is such that it was only worth doing on the larger > 500 kW engines from the owner's point of view, at the bid closing prices.

So if  it's not competitive to do on even  200 kW engines at current STOR contract prices (so as to compete with Dinorwig etc), what on earth possesses you to think it would be commercially viable on 3 kW domestic electric water-heater disconnections?

I do wish you'd desist from these ill-thought  generalisations. Technically possible and economically competitive are 2 entirely different things ("it's the economy, stupid!" - W.J. Clinton).

 

Could you/Mark D. please also reconcile your quoted '5 - 20 minutes' startup requirement for the STOR generators (which sounds more likely) with the '240' minutes  max. notice period quoted in Mark Duffield's referenced Claverton website article.

 

Regards, Chris Hodrien.

----- Original Message -----

From: dave andrews

To: grid-supergrid-in...@googlegroups.com

Cc: carbon-c...@googlegroups.com ; Claverton AB MAIN GROUP ; large-power-conventional-power-...@googlegroups.com ; Andrew Smith ; mark.duffield ; Nick Jenkins ; Goran Strbac ; e.a.be...@dundee.ac.uk

Sent: Friday, August 20, 2010 3:07 PM

Subject: Re: wind backup - flywheel energy storage vs STOR diesels

If I can add a bit more to the excellent piece from Ted of Carbon Catalysts and David Hirst

 

If frequency drops below that which the governor mechanism outlined below by Ted East can deal with, then the next thing that happens is for  all the large power users, such as steel works (are there any left)? cold stores and such like who have entered int a Frequency Service contract with NnGrid, and whose relay is armed, this relay instantaneously trips off the main power supply.

 

These relays are set at a range of settings so that as the hz falls, more and more load is tripped off until the frequency stabilises.  NG has about 2 GW ? of such load under contract and you can earn about £50/MW per year.

 

Such disconnections are contracted to be for no more than 20 minutes in the main - which is immaterial to a cold store, or melting furnace.

 

Simultaneously with these load disconnections, Ngrid also sends out a signal to all the participants in STOR - short term operating reserve and this is at least 500 kW of emergency diesels, plus sundry gas turbines, part loaded steam and so forth, and probably quite a lot of Dinorwic (which is why I doubt it earns much from arbitrage since STOR is much more lucrative).

 

The STOR participants are required to be up and running in a range from 5 - 20 minutes, and as soon as they are up, Ngrid turns the frequency relays back on, and re connects the loads.

[dave andrews]

Chris - I am always puzzled why you appear to get so cross and need to become so offensive when discussing these things.

 

The reason these other diesels haven't been contracted is because NG doesn't need them - yet - it has enough so hasn't encouraged more users to get involved.

 

If it wanted to it could up the marketing and draw more users who are simply unaware of the possibility.

 

I am working with a large blue chip who have been blissfully unaware of the possibility until i told them - they could be making £900k/per year and having more reliable generators.

 

At £40k conversion for say a 200 kw set this is far cheaper on a per kW basis than one of your gas turbines.

 

There is simply no comparison between putting a diesel on to STOR and making a load disconnect able.

 

For years this has been possible and done with say  a Horstman meter which could pick up a radio signal from Long Wave and switch domestic night storage heaters.  Ripple control has been used for years to remotely switch water heaters and lower power street lights.

 

Such remote switching is routine, low cost,  and you should know that so switching 3 kW water heaters, kettle circuits and night storage heaters (proper ones - not the cheap nonsense we have in this country0 is perfectly feasible and economic.

 

If you wish to continue to discuss this with me, kindly adopt a less offensive approach.

 

I can't be bothered to address your last point since you clearly don;t understand it and life is too short.

 

Dave Andrews

[bernar...@aol.com]

Chris,
I think that the issue is getting a little confused. The disconnection
of domestic heaters has been sucessfully used for many years by
municipal undertakings who were able to defer investment in increased
generation or import capacity. They used ripple control which was far
from perfect and manual resetting of a small proportion of the
contactors was a routine job. With modern telecommunications and
controls which can include predictive software it isn't very difficult.
I suspect that if the industry were fully integrated with present and
future anticipated costs for firm capacity this would be viable. As
far as the use of standby diesel generation is concerned, it is
necessary to look at each on a case by case basis. For a new
installation, where the low voltage switchgear can have synchronizing
equipment, adequate fault level, properly sized fuel tanks and
appropriate protection for 'export' from day one into a suitable
distribution systemsit is viable from about 250kW on selected sites
but more commonly arround 400kW. As the same kit is useable for Triad
management the part of the UK matters as well. The National Grid have
little interest in items below 3MW. Thus the generators need to be in
an organisation with engineering and commercial awareness, preferably
existing control facilities to and the wit to consolidate reasonable
sized blocks of generation to respond to the NG signals. Selecting
generators in service for retrofitting takes some effort. The number of
suitable outfits arround isn't that many. In France where EdeF have
taken the inititive to cover trips at nuclear plants I think there is
about 5GW of 'STOR'
At the end of the day they are only suitable for short term back up.
Incidentally using internet connections and a good DCS allows the
diesel generators to be on line in about 30 seconds which more than
meets the NG requirements. There is a lot of thought needed to assemble
a significant portfolio but it can pay. I think knocking off large
motors in process plants is much easier and that of course is where NG
find much of the 2 or 3 GW of capacity they contract for frequency
services.
Regards
Bernard Quigg

-----Original Message-----
From: Chris Hodrien <chod...@blueyonder.co.uk>
To: Claverton- Large Powerplant Web-Group
<large-power-conventional-power-stations-operatations-claverton@googlegro
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<e.a.be...@dundee.ac.uk>
Sent: Tue, 24 Aug 2010 11:49

Subject: Re: wind backup - flywheel energy storage vs STOR diesels

Regards

Dave Andrews

Dave,

Regards,

Ted

Thanks

Dave A

Regards,
Andrew

--

3 Victoria Place

[Chris Hodrien]

Dave A./Dave E.,

Dave(s), I am quite happy with the proposition that nuclear (or any other equally sized fossil steam turbine for that matter) poses the largest instant* breakdown  threat on the grid, requiring a particular type of very rapid-response backup plant. This increased margin is to do with increase in individual unit size, nothing to do with the overall number of nuke stations as hinted. I believe that this instant-breakdown backup provision element should equitably be assigned to the large nuclear units causing it, (at least as a group) on the 'polluter pays' principle, just as I consider that 'wind-out' backup (see below) should similarly be fairly assigned to the wind farm operators.  So 'smearing' it over all power providers is a bit of an NG 'cop-out'.

 

Whereas of course it's a large wind fleet that poses by far the largest cumulative 'fleet' loss-of-load threat over a gradual period (say 12-24 hours) during national-scale 'wind-outs'. These two aspects of backup duty should not be confused or conflated.  Suitable flexible backup plant, (+load-shedding, STOR diesels etc etc) etc has to be provided to cover both eventualities, with the latter by far the larger in terms of plant capacity. 

 

The reported item is a 'lobbying piece'. Wind is not being specially 'picked on', just being asked to carry its own fair per-MW (rated capacity) share along with all the fossil generators. The fact that they will only deliver about 30% revenue relative to that rated capacity (making the capacity-based Large Loss Response levy larger in proportion to their annual output)  is wind's own technical problem, not Nat Grid's.

Chris Hodrien.

----- Original Message -----

From: Dave Elliott

To: energy-disc...@googlegroups.com

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Sent: Tuesday, August 24, 2010 2:10 PM

Subject: Re: wind backup - flywheel energy storage vs STOR diesels

The article  pasted below, published today, raises some disturbing  prospects of cost escalations for wind farms due to  the requirement to  upgrade the  grid backup  to  accomodate new nuclear power. 

 

Exclusive: Will wind farms pick up the tab for new nuclear?

Wind farm developers fear National Grid proposals designed to accommodate nuclear power plants will lead to a huge increase in backup costs

James Murray, BusinessGreen, 24 Aug 2010

http://www.businessgreen.com/business-green/news/2268599/exclusive-wind-farms-pick-tab?page=2

 

Wind farm operators could see their overheads increase by millions of pounds a year as a direct result of plans to upgrade and reinforce the grid to cope with a new fleet of nuclear reactors.

A number of renewable energy developers are angry at National Grid's decision to retain the current charging regime it operates for providing backup power, despite the fact costs are expected to soar when new nuclear power plants come online towards the end of the decade.

National Grid released a consultation document in June detailing how the proposed development of six nuclear power stations would require the grid operator to increase the amount of backup power, known as "spinning reserve", that it has available to call on in the event of a large power plant failing, from 1,320MW to 1,800MW.

The company estimated that as a result, the annual cost of providing so-called Large Loss Response will rise from £160m a year to £319m.

The consultation looked at a number of approaches to charging energy firms to cover the increased cost, but in a letter to Ofgem National Grid commercial director for transmission Alison Kay said the company had decided to retain the current regime, whereby generators are charged an equal amount per megawatt they provide to the grid.

Wind farm operators are known to be furious at the decision, which they claim will see them face an unfair doubling in charges from National Grid, despite the fact the company concluded in its consultation that generators with less than 350MW of capacity, including all operational wind farms in the UK, "pose no additional loss risk to the system".

In contrast, nuclear developers, who argued that targeting the increased charges at larger power plants would jeopardise plans for a new fleet of reactors, are delighted at a decision that will see the increased cost of backup spread right across the energy industry.

Writing in her letter to Ofgem, Kay revealed that the decision to retain the current charging regime was driven in part by fears that changes would delay the new nuclear build programme.

"Information received through the recent consultation indicates that increasing costs on larger users could delay the commissioning of a large nuclear plant by a number of years, with any shortfall in generation capacity likely to be made up through a new CCGT [combined cycle gas turbines] plant," she said. "This eventuality would increase the difficulty in meeting European and governmental environmental targets by delaying essential investment in lower-carbon technologies."

Speaking to BusinessGreen.com, a spokesman for National Grid admitted some wind farm operators were frustrated by the decision. But he argued that developers working on larger offshore wind farms that will generate more than 350MW were pleased that they would not now face additional charges.

However, wind industry insiders insist support for National Grid's proposals among offshore wind farm developers is in fact very low. They argue that even the largest proposed offshore wind farm sites are likely to use a number of different cables to connect them to the mainland, meaning any one connection is unlikely to exceed the 350MW mark that would mean they pose an additional risk to the grid.

Some wind farm operators are now urging Ofgem to challenge National Grid's decision, arguing that the proposed charging regime will result in wind farms and other renewable energy projects effectively picking up a sizable chunk of the bill for the nuclear industry. They are insisting that Ofgem should adhere to the "polluter pays" principle and make sure nuclear operators pay for the additional backup capacity that they will require.

There are also suspicions within the industry that National Grid has been " leaned on" by the nuclear lobby in order to ensure the increased cost of backup is shared by all generators – a charge rejected by National Grid.

 

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The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302).

[dave andrews]

David S - yes interesting point - I have heard that NG are going around trying to find out how many gas units are off line "resting on thermostats" ready to be fired up for STOR......

 

Anyone heard about htis?

 

Thanks

 

Dave a

On 25 August 2010 11:25, Sanderson David (QBE) <david.s...@edf-energy.com> wrote:

In relation to the use of diesels for back-up:

 

Beyond the fleet of diesels that are capable of providing reserve for NG, there are smaller capacity ‘standby’ diesels for emergency back-up – e.g. data centres, hospitals and commercial offices. Typically these have limited fuel storage as loss of grid supplies is rare and will be of limited duration – indeed most running is for short testing periods. As such operation of ‘standby’ diesels on diesel fuel is usually restricted by environmental permits which limit running time to avoid local air quality problems and noise issues.

 

Also there is a fleet of modified diesels in the UK that run on natural gas so the environmental issue is not so challenging; e.g. swimming pools and hotels. Many are part of cogeneration schemes so will generate more often based on the overall economics of burning gas to produce heat and electricity instead of buying in electricity. With this fleet not being for ‘standby’, some capacity could not be relied on to provide reserve as it would be operating when NG called on it to provide reserve.

 

David       

     

 

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