Diesel Gens as transition back up - Gary Swandells and other Demand Side Management - UK Electricity - full article in FT

[dave andrews]

........................................"Alastair Martin, Flexitricity’s founder and managing director, said that as well as bringing new revenue to UK businesses and reducing carbon emissions in the electricity system, this would make the generation of renewable energy much more viable, because it would provide a low-carbon backup to offset the variability associated with wind, wave and solar power generation.

“So it is not the case we’ll be running Manchester – but we do intend to be big enough to pick up the load of a large nuclear station as it drops.”

Mr Martin said that by aggregating smaller electricity generators, it would be unnecessary to keep the older coal-fired or oil-burning power generators operating inefficiently.

“There is more than enough unexploited capacity in the hands of industrial and commercial energy users to provide all of the reserve electricity that National Grid requires until 2020 without building a single additional power station,” he said.

Copyright The Financial Times Limited 2010. You may share using our article tools.".....................................

 

Full article here.................

Linkedin Groups	September 6, 2010
Demand Side Management - UK Electricity
Discussions (1) FT.com / Companies / UK Smaller Companies - Flexitricity aims to bolster power grid Comment or flag » Started by Gary Swandells, Commercial Director

--

David Andrews

UK Sales Representative

3 Victoria Place

Combe Down

Bath BA25EY

United Kingdom

Tel.:+44 (0)1225 837 978

Mob: +44 (0)755 265 9166
http://www.etra33.si
uk.kolek...@gmail.com

[Chris Hodrien]

Dave, you and I have been 'round this loop' via Claverton groups at length only a couple of weeks ago, so I'm surprised/disappointed that you naively reproduce Alastair Martin's piece without some 'back-reference' comment to that discussion. Just because Alastair says it, makes it no more valid than you. With respect, (while STOR-contract diesels have a useful well-defined, limited, specific niche operational role for Nat Grid - I said nothing about 'low-carbon'), Alastair's comments are a bit of opportunist kite-flying (I'm happy to debate direct with him via Claverton if he wishes).

 

1. The sort of capacity (single-unit nuke breakdown) he's talking about is only c.2 GW (inc' ALL currently contracted sources of 'end-user' backup inc' load-shedding, NOT just the diesels), just 1/16th of the capacity needed to cover a 'fleet-wide' (say) 5-day winter calm 'wind-out' situation for the 33 GW wind programme. The latter is several 'Manchesters'.

 

2. I believe that it is normal Nat Grid practice that these STOR contracted end-user generators are only run for up to c.20-30 mins on average (per start) before other forms of power co. 'supply-side' plant pick up (I would love someone more knowledgeable from Nat Grid to contribute on this aspect -please?).   30 mins = only 1/240th of the duration of a 5-day 'wind-out'. (1/16 capacity x 1/240th = 1/3840, or 0.026%)

 

3. Part of that 'calculation' is that the STOR diesels are far from 'clean' and it's very disingenuous of Alastair to hint that they are. Does he think the whole readership is stupid? I would love to see the real numerical comparison (preferably by Nat Grid or DECC ) for CO2, SOx and NOx emissions as a function of diesel running time (anyone fancy some 'DIY' calc's?)  - I bet there are some sharp 'cross-overs'. The comparison needs to cover at least 4 cases: current unabated coal plant: post-LCPD/ IED (2023) 'clean' non-CCS coal with SCR de-NOx; new-build 'Clean coal' with CCS (cf. EOn Kingsnorth design); and unabated latest-generation (60% LCV) CCGT.

Of course, the STOR engines would have a much 'cleaner act' if the contracts were restricted only to gas engines, preferably those with exhaust SCR de-NOx. Wonder how that (reasonable) restriction would affect the available fleet size and contract price? The problem of course is that only a tiny % of emergency standby generators are gas (or biofuel)-fuelled, while the majority of gas engine plants (especially CHP) are justified on long annual running hours/ % loads and thus not available most of the time to 'stand by' for STOR-type service (especially at peak grid load times) .

 

I have already argued (with no rebuttal so far?) that a combination of wind fleet + normal 'supply-side' fossil [coal+gas-CCGT] backup ('like for like' on the fossil component re. emissions control ) is unlikely to achieve more than c.25-26% CO2/SO2/NOx reduction (for that 'fleet' alone, never mind the whole grid!) - i.e. well short of post-2025 gov't targets.  A combination of wind + STOR diesels would (obviously) be far worse, my guess would be max. 10-15% reduction.

 

It has also been argued by you and others that real 'wind-outs' a) can be approximately forecast several days ahead and b) have a very gradual load reduction ramp, hardly even requiring 'extreme' rapid back-up  measures like STOR diesels. This is probably true. But you also need to cover the much more serious (if rarer) high-wind-speed (storm) self-protection 'instant' WT  trip situation, such as happened for real* on a 'fleet-wide' basis in West Denmark back in 2003(?) as so vividly described for us at a past Claverton Conf' (and in articles since) (from personal expert knowledge) by Paul-Frederik Bach ( -do you have a 'selective memory'?). (Paul-F., can you share with us any info. on how the Danish grid authorities plan to deal with this scenario next time, at the proposed increased % wind penetration??). There may well be a technical 'fix' to this rapid WT trip problem (comment please, wind experts!), but the key issue is what % of the planned 33 GW wind fleet (i.e including all the existing turbines) will be mandated to/ actually have that (expensive?) feature in practice.

 

Can we 'get real', please.

Regards,

Chris Hodrien

 

Principal Technical Consultant, Expansion Energy Ltd

[dave andrews]

Chris - whilst at Wessex Water we paid Dr Barrett to compare the emissions of of the UK grid with and without load management diesels which Dr Barrett is able to model.

 

It turns out as I recall that CO2 emissions are substantially less with diesels in play, because whilst they only run for a very short period of each year, they permit a much lower level of coal plant on spinning reserve running inefficiently at part load.  So you are trading 8760 hours of spinning reserve for say 40 - 200  hours of diesel.

 

Of course in the the long term the diesel could easily be Jatropha or other low carbon oil source.

 

It is true that diesels are only used for about 40  - 200 hours per year by grid - but that does not meant they could not run for much longer periods if needed.  In this case the past is no certain guide to the future. On occasions the Wessex diesels have run for 24 hours when there was a shortage of gas fired plant.

 

Nobody has ever argued that diesels alone will solve the intermittentcy problem - a combination of better interconnections, diesels, more storage in dwellings, gas turbines etc will solve it.  It is essentially the issue of starting up coal plant to cover wind out, and as we know it only takes about 4 hours to get a coal plant up and running without exposing it to abnormal stresses..............

 

As Andrews Smith has pointed out - Denmark is a tiny country and the effect of a storm front is much more severe than the stress of a storm front moving over the whole of the UK and Ireland.

 

I do not see why a large wind turbine fleet, with the necessary mods as outlined above, could not deliver carbon savings on a 1:1 basis - you have not shown where all this extra carbon is going to be expended in balancing, and until you produce a model which shows this then you are simply speculating.

 

Kind Regards

 

Dave A

[dave andrews]

Alastair,

 

Great post thanks.

 

I would just like to confirm that diesels have never been suggested as a back up for diesels in the sense of "when no wind, just run the diesels" . I ahve alwasy emphasised that they are part of a transistion from say a sudden UNFORCASTED drop in wind speed, and would theregy be used to allow conventional plant to have their output increased.  They are a transition technology in this sense.

 

Another point I think you missed is that if the situations occured that a large part of the wind fleet were runing flat out,

On 8 September 2010 11:13, Alastair Martin <alastai...@flexitricity.com> wrote:

I agree with all of Graeme’s comments.  His description of STOR is pretty much what happens.  While I don’t agree with all of Chris’s comments, I can’t dismiss them.  I’ll answer some of them here.

 

What happens now:

 

Diesels are less than half of the capacity which Flexitricity manages.  We also have CHP, short-duration load reductions, and small hydro.  We do different things with different types of capacity.

 

We mainly limit diesel run times to no more than two hours at full load, and we cap the number of runs per week and per year.  We get less than 100 hours/year running on most diesels.

 

Role of diesels in system balancing:

 

Diesels are not for wholesale wind balancing.  That’s madness; I’ve said this before.  Diesels are for catching large, fast-moving events, and holding things stable for long enough for something else to be teed up.  The only place where diesels should shadow wind is on an island where all you have is diesel and wind.  In that context, batteries would do better.

 

In the vast majority of cases, STOR calls have nothing to do with wind generation.  Where a cause can be discerned, it will be a trip at a coal, gas or nuclear power station, a problem on the interconnector to France, or unexpectedly high demand.

 

How to follow wind:

 

Huge unanswered question.  Not with diesels burning fossil fuel.  Here are some ways, well known to this group:

-          Interconnection

-          CHP scheduling using heat/coolth stores

-          Some biomass (possibly including diesels burning difficult fuels, like tallow)

-          CCGT/CCS

-          Pumped storage

-          Flow batteries

-          Responsive EV charging, and possibly vehicle-to-grid systems

-          Large-scale demand schlepping from low wind periods to high wind periods, using storage, inertia and myriad other methods

 

Most of those are not easy, and some are extremely hard.  Nevertheless, I honestly expect that we will see all of them in a low-carbon system.

 

What diesels will do if left alone:

 

If left completely alone, diesels are useless.  Neglected diesels routinely fail at the moment of greatest need.

 

If kept to a local site emergency role but properly managed, diesels will be regularly exercised on-load.  Around 50 hours/year on load is fine.  This is close to the run hours most of our diesel clients get from STOR.  The conclusion is obvious: let STOR be your test and exercise regime, because at least then you’re doing something useful.

 

What the national system will do if it has no demand-side:

 

Other than in the midst of a recession, Littlebrook, Grain, Fawley, Kingsnorth, Cockenzie and similar coal and oil stations receive frequent instructions from National Grid to warm up on a just-in-case basis.  This is to create reserve, or margin.   Lately, more warming instructions have gone to CCGTs, which are better, but that’s partly a recession thing.

 

Warming consumes fuel, whether the plant is synchronised or not. 

 

Synchronising a warmed plant wastes fuel, because something else must be turned down to make room for it (you have to get the warmed plant up to its stable export limit).  Only when synchronised do you actually have access to the margin in short order.  Here’s where CCGTs don’t shine: their efficiency falls away faster than other stations when turned down.

 

Only when the unforeseen situation arises (and it will always be unforeseen; that’s what margin is for) will the warmed and synchronised plant ever deliver any useful energy.  It will still have a limited ramp rate (for example, Drax can do 20MW/minute if paid enough).

 

What the national system will do if it has demand-side:

 

This is true whether the demand-side flexibility comes from diesels or anything else.  The system operator will do the sums, decide how much margin is needed, subtract the portion that is already there on the demand side, and only warm or part-load the remainder.

 

Meanwhile, the demand-side capacity (made up of diesels, load management, idle CHPs and hydros) is sitting doing nothing, burning nothing, and is ready to respond in minutes.

 

THAT is the nub of our environmental claim.  The sums are complex and should ideally be re-done regularly, but the basics have at least been investigated.  The report is online (http://www.flexitricity.com/resources).

 

You can make similar claims about OCGTs, and in fact their role is similar.  When running, most (not all) have a higher fuel cost than diesels.   This is a minor part of the sum; the real value is in being available.

 

Another minor part of the sum is that when the margin is called upon to deliver, the system operator is already at or near the limit of what it can get from synchronised plant, so the fuel burn on the demand-side should be compared to the fuel burn at the margin of the market.  This is contested by some, but I think it stands up.  It’s not always the case that the marginal plant produces CO2 faster than diesels, but it will generally be true in the current market.

 

The role of diesels in a zero-carbon electricity system:

 

Truly zero?  Then good-quality and environmentally-credible biofuels, or no role at all.  To live without diesels, local emergency power generation will require batteries of some kind, as will the sudden loss of infeed scenario (large nuclear stations tripping).  That’s a very big change.  Either way, where there are standby diesels, there will be testing, and where there is testing, it should be made useful to the national system, hence STOR, triad management, etc.

 

Hope this clarifies

 

Regards

 

Alastair

 

 

 

From: grid-supergrid-in...@googlegroups.com [mailto:grid-supergrid-in...@googlegroups.com] On Behalf Of Graeme Bathurst
Sent: 07 September 2010 23:09
To: grid-supergrid-in...@googlegroups.com; Claverton- Large Powerplant Web-Group; Claverton AB MAIN GROUP
Cc: Paul-Frederik Bach

Subject: Re: Diesel Gens as transition back up and other Demand Side Management

 

Chris

Just some details but I'm not commenting on the thread.

STOR - from memory there is a minimum require run time capability of 2.5hrs to be eligible for a contract although depending on your availability/utilisation prices, NGT will select and run for their desired time. I'm fairly sure that they are mainly used while slower start larger/more efficient reserve units are brought on line, or ramped up (ie this is only Short Term Operating Reserve). 20-30mins is possible reasonable but this is due to system dynamics rather than capability etc.

WIND - turbines typically go into controlled shutdown at wind speeds in excess of 25m/s which constitute high storm conditions. This is an economic design consideration. I suspect you could stagger the shut-downs using 23-25m/s or have a progressive derating at high windspeeds to secure the system if this became a significant systemic risk.

As a power system engineer I'm fairly relaxed about all of this as is just about system integration and avoiding having cliff edges in your system which of course can cause accidents. It's basic risk assessment, either mitigate the risk or remove the hazard. Removing the hazard is always preferable and I can see other ways of dealing with this other than just blocking wind. The risk is going in with our eyes closed rather than managing the situation. So I don't disagree that we need a clear considered strategy which in some cases is not happening, but managing high levels of intermittency is technically and economically possible - not BAU though....

Regards

Graeme

Sent from my BlackBerry® wireless device

---

From: "Chris Hodrien" <chod...@blueyonder.co.uk>

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

Date: Tue, 7 Sep 2010 10:14:59 +0100

To: Claverton- Large Powerplant Web-Group<large-power-conventional-power-...@googlegroups.com>; Claverton Supergrid group<grid-supergrid-in...@googlegroups.com>; Claverton AB MAIN GROUP<energy-disc...@googlegroups.com>

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

Cc: Paul-Frederik Bach<pfb...@profibermail.dk>

Subject: Re: Diesel Gens as transition back up and other Demand Side Management

[dave andrews]

PREMATURELY SENT EARLIER

Alastair,

 

Great post thanks. -  Can I suggest you post  your piece on the Claverton site, Alastair/

 

I would just like to confirm that diesels have never been suggested as a back up for diesels in the sense of "when no wind, just run the diesels" . I have always emphasised that they are part of a transition from say a sudden UNFORCASTED drop in wind speed, and would thereby be used to allow conventional plant to have their output increased.  They are a transition technology in this sense. Along with the other techniques that you mention.

 

Another point I think you missed is that if the situations occurred that a large part of the wind fleet were ruining flat out,  which is a rare occurrence according to Sinden's analysis, then a significant proportion can be constrained off which has the same effect as a lot of diesel sitting there as they can instantly be constrained on if wind speed suddenly drops.

 

 

 

Kind regards

 

Dave Andrwews

[bernar...@aol.com]

Dave,
it is perhaps worth mentioning that a DTI financed study showed that
the reduction in CO2 by utilising diesel generators. I believe Alistair
Martin was involved in the study which no doubt explains his
enthusiasum for STOR.
Regards
Bernard

-----Original Message-----
From: dave andrews <uk.kolek...@gmail.com>
To:
large-power-conventional-power-stations-operatations-claverton@googlegrou
ps.com
CC: Claverton Supergrid group
<grid-supergrid-in...@googlegroups.com>; Claverton AB

MAIN GROUP <energy-disc...@googlegroups.com>; Paul-Frederik
Bach <pfb...@profibermail.dk>; Hugh Sharman <sha...@incoteco.com>;
Wayne Boakes <wayne....@wessexwater.co.uk>; Mark Barrett
<mark.b...@ucl.ac.uk>; Robert Lowe <rober...@ucl.ac.uk>
Sent: Tue, 7 Sep 2010 11:18
Subject: Re: Diesel Gens as transition back up and other Demand Side
Management

 

Discussions (1)

 
 
 

--

3 Victoria Place

Combe Down
Bath BA25EY
United Kingdom
Tel.:+44 (0)1225 837 978
Mob: +44 (0)755 265 9166
http://www.etra33.si
uk.kolek...@gmail.com

--

David Andrews
UK Sales Representative

3 Victoria Place
Combe Down
Bath BA25EY
United Kingdom
Tel.:+44 (0)1225 837 978
Mob: +44 (0)755 265 9166
http://www.etra33.si
uk.kolek...@gmail.com

`1q