How to Turn Standby Generation Into Profit-Making Assets

By Wayne Boakes

It does not make sense to ignore assets, leaving them idle, collecting dust and slowly degenerating (excuse the pun).  Ask yourself why we spend thousands of pounds on standby generation just to have it lying dormant, gathering dust?   Surely it makes much more sense to generate a profit from at least some of these assets.

With the continued expansion of wind energy the national grid need to increase their ability to cope with power fluctuations.  They are already discussing ways in which they can encourage increased participation in Short Term Operating Reserve (STOR).
What is the solution?  One solution is to increase use of embedded generation

What do we expect from a standby generator?  To run once in a blue moon, start first time, take the entire load thrown at it and to do this without a cough or splutter.  Strangely enough all too frequently the emergency arrives only to find the generator won’t start as the battery is flat or the fuel is not getting through or it fails during the run.  It’s not surprising really.  If the generator was a person and we expected immediate response at premium performance we would do something more that just sit around like some couch potato. We would join a gym, do regular exercise and have regular checks to make sure we were in tip top condition.

Did you know that regularly operating generators on load is like going to the gym?  The set gets up to operating temperature, oil, coolant and additives are circulated throughout the set.  Moisture is dispersed, fuel is used and re-circulated, batteries are discharged and re-charged, bearings are rotated etc, etc. Also as you are putting the set on load you are putting it through its paces and under strain. This can bring out any underlying issues that can be addressed straightaway to ensure there are no problems when the set is called to run in an emergency on a dark stormy night.

If you had the choice between couch potato or an athlete in tip top condition, which would you choose?  The concept of the Wessex Water Load Management system is simple.  The set is modified to allow it to run in parallel with the mains.  A remote control panel is installed, which enables the set to be started and stopped whenever required.  Combining a number of sets on the system enables Wessex Water to offer services such as load reduction and triad avoidance to 3rd parties.  The income from these services can be used to finance additional maintenance and repairs and still make a profit. By using the Wessex Water Load Management system and modifying a set you are able to run the sets regularly, address any issues that arise in a timely fashion and earn a little extra.

How have Wessex Water done this?  Their system currently has 34 sets on it which can either be run individually or at the same time.  They can start or stop the whole portfolio within minutes or schedule a run for some time in the future.  During a run someone watches for any abnormalities and takes appropriate action.  The income and avoided costs encounter are partly re-invested in maintenance and taken as profit.

Depending on where you are in the country effects the value of what you can make because a large percentage of the value is in Triad avoidance or export.  In the south west you can earn up to £20,000/MW, which soon mounts up if you have 10MW of sets available.  It is not usually cost effective to use sets that are smaller than <500kVA as the payback is too long.

If you are interested to find out more on how Wessex Water Enterprises system works or are interested in WWE managing a portfolio of sets for you please contact Wayne Boakes on 07831 140534.

Services WWE can offer include survey of your assets to identify potential sets. Compile estimates of cost for conversion, manage conversion, operate and maintain and pay an access fee for the privilege.

Please note: None of the comments below are from the author of this paper, Wayne Boakes, but varous Claverton users.

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18 comments on “How to Turn Standby Generation Into Profit-Making Assets

  1. hi,
    i am a graduate trainee with a hydropower company.We have projects in remote sites where we are using DG sets in standby mode.
    So kidly if you can elborate on the economic use of the same, it would be great.
    We are using cummins DG sets of the range: 25kVA-600kVA.
    What are the possible fuel conumption limits?

  2. Hi – of course it depends which country you are in and what the tariff arrangements are. In the UK in the West of England, where the Triad payments are highest, 1MW of diesel will earn 25,000 pounds per annum plus another 7,000 from Reserve Service. This will be roughly pro rate for different outputs.
    In the West of England the limit is about 150 – 250 kW to make it worth while, but you must of course be grid connected.
    Fuel consumption is pretty irrelevant as all diesels are about the same and the cost of fuel is tiny compared to the benefits.
    But I am guessing you are off the grid, as why bother with standby generators, in which case you won’t be able to earn any money.

  3. hello,

    i have a question concerning a dieselgenerator.
    is it possible tot regulate this generator whit a frequention corrector? how do we do this?

    best regards

    Dimitry Van Havere

  4. Yes – you can fit an electronic governor and automatic symchroniser to most diesel generators – Heinzman and Woodwards are leading manufacturers.

  5. HELLO

  6. You really need to obtain professional help on this.

    The manufacturers will tell you the minimum loading per set, but it will be around 30% of full load if run continuously.

    To test sets you will need to load each set to its full rated output.

    With no grid, load banks can be easily fabricated from 50 gallon oil drums filled with water and salt, and with an electrode lowered into the salt solution.

    You should really contact someone like First Energy of Hereford who specialise in this kind of thing and work closely with the engine manufacturer.

  7. Health and safety issues have been raised wrt the above comment. Obviously only professionally experienced and skilled people should consider carrying out the above activity – that goes without saying.

    However salt tank load banks are or were quite often used in out of the way places where they can be readily fabricated if you know how.

    In recent memory the Petbow works, latterly Cummins works at Ramsgate had a whole bank of these load banks steaming away – some dissipating 1 MW.

    From a recent blog:

    Registered-II Join Date: Jan 2006
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    Salt box load bank questions


    Hi and happy new year to all !!

    Back in the seventies I worked at a boatyard. We overhauled small boats like the LCM,s and LCU’s among others for the Navy, Army and the Corps of Engineers. The electricians there built a salt box load bank. It was a large wooden box lined with metal (maybe 100 gallon capacity) They made a metal grid which could be raised or lowered into the water to control the load with a small winch. Water was pumped through some coils to control the heat.
    My questions: Where can I find some info and plans to build one ? Just what type metals are needed ? How much box and grid area are needed for X amount of kw’s ? What about building one for three phase ? What amount of salt is used if any ? Is such a thing even legal to build and use ?
    We presently have two load banks, one is 10 kw and the other is 100 kw. Sometimes we need to test larger generators and as you know load banks cost lots of $$$.

    Thanks, Mark

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    #2 01-12-2008, 10:13 PM
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    Re: Salt box load bank questions


    Hi Mark
    I have never seen a salt box, heard of them though.
    I have seen tham made out of electric furnace elements.
    It was a sheet metal duct with a fan installed to cool the coils.
    There was several different coils inside selected with a bunch of large switches. 120240 single and 3 phase was no problem. 480 volts was a problem, burned out every coil that was turned on. I think you would have to put 2 coils in series to use that voltage. I dont think I would use it above 50 KW. Or your salt box also! I know the guys I work with have used as many as 5 100KW loadbanks to do a 500KW unit that was 9 stories up. Packed all up there and hooked everyone of them up at the same time.
    If I get back to the furnace coil loadbank I will take a picture of it.
    I see loadbanks on Ebay once in a while.

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    #3 01-12-2008, 10:38 PM
    Jack Hottel
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    Re: Salt box load bank questions


    From a post I made on 11/29/05.
    I used salt water. I took 1/2 an 55 gallon drum and mounted a post on each side with nails/notches to support a non-conducting crossbar at different heights. Two(or three) copper electrodes made from old pipe were attached to the crossbar, short enough so as not to touch the bottom of the drum. The power is fed to the two(or three) electrodes and the neutral is tied to the drum itself.
    Fill the drum about 2/3 full of water, set the electrodes all the way down, turn on the power and add salt until you get the current you want. As the water warms the current will increase. Raise the electrodes to decrease it as necessary. When the water boils it will stabilize. I have had no trouble loading to maximum on a 15kw unit (62.5 A single phase).
    As always be careful when working with exposed terminals that are hot both electrically and thermally.

    Of course I only needed to dissipate 15 KW so I made a small one , but the principal is the same. Run it boiling, the heat is dissipated as steam and you just need to add makeup water. I had more electrode than I needed using 1 inch copper pipes about a foot long.
    Jack Hottel

  8. More on salt water rheostats – I know Caterpillar engineers who have fabricated these quite safely for commissioning in MW generators in Africa with no load banks.

    Obviously this is a subject where skilled experienced professionals should be in charge.

    winnie03-10-2008, 11:51 PM
    If one were to actually want to build a water rheostat load bank, I’d suggest looking through old books on the subject.

    This is technology that was invented, refined, and then obsoleted. While it may very well have present day applications, I would not want to try and _reinvent_ the technology.

    That said, it looks like someone has been busy reinventing:

    Looks like Lindsay has a reprint:

    Some of the books that google has digitized show designs,
    just do a books search for “water rheostat”, and specify that you only want to look at results where the full book is available. paragraph 454 says ‘there is always more or less risk of getting shocks when adjusting…’

    Here is a 700KW 2.3KV three phase water rheostat design. They specify a running stream; I wouldn’t want to be swimming anywhere nearby….

    Have fun reading. If you actually build anything, you don’t know me 🙂

  9. From: EGSA – Electricity Generating Standards Association
    artifical load (water rheostat).

    A tank containing a salt or brine and water mixture in which electrodes are submerged to create a load. The deeper the electrodes are submerged into the mixture, the greater the load. To stabilize the load, the mixture must not be allowed to boil. This type of artificial load operates at unity power factor.


    3. APTA RP-E-003-98
    Recommended Practice for Load
    Testing of Diesel Engines



    “4.2 Loading of engine

    When the engine is tested in place on the locomotive, horsepower readings should be
    adjusted to the standard test conditions as described in 4.6. The main traction generator
    should be loaded by means of a water rheostat or resistance grid bank of sufficient
    capacity to load the generator to its maximum rated capacity plus any overload permitted
    by the manufacturer.”

  11. Railways commonly used salt-water load banks back in the fifties to test the HP output of diesel-electric locos. I recall using them as a railway apprentice before they were replaced by specially designed resistive banks from suppliers such as EMD, GE and Moseback.
    These later designs, rated for 4,000 hp, currently cost in the region of 100,000 to 180,000 euro. Therefore it’s easy to see the attraction for cash starved railway works to build their own salt-water type.
    Admittedly, the loco type would be unsuitable for 3-phase testing, as these locos were strictly DC.
    My recollection is of a steel cylinder (the negative), about 5-ft in size, possibly two off, standing on insulators, in which was suspended a hollow steel cylinder. This acted as the positive electrode and was supported by a steel rope and insulator from an adjustable pulley. The water pipe connection included an insulated section.
    The “tank” contained, of course, salt water, but not at the concentration that could be described as “brine”. The whole contraption was fenced off for safety.
    Operation was very simple, as adding more salt, more water or varying the height of the centre electrode would vary the load. The load proved to be quite stable, varying only slightly as the water heated up; it never came to the boil.
    Power dissipation was about 1MW, with voltages of about 700 & current of about 1,500A.
    The only problem was corrosion to the copper connection cables & to the wire rope, which did actually break one day and fall into the tank, though not while in use thankfully.
    Another advantage was silent operation with none of the fan noise of current resistive grid designs.
    One disadvantage is lack of insulation from ground, as this type will definitely trip any modern gen. ground detection system fitted.
    The salt-water load bank dates from an earlier, less regulated and litigious era. To pass current H & S criteria would require very careful operation.

  12. From Wikipedia:

    some ill-informed people are unaware of how useful these devices are in remote areas and quite safe in the right hands….[[User:Engineman|Engineman]] ([[User talk:Engineman|talk]]) 11:20, 14 May 2009 (UTC)
    + :They’re no more dangerous than [[Electric heating#Electrode heater]]s, which work on the same principle, but with plain water, provided the correct precautions are used. This requires connecting the container to both ground & neutral and breaking all poles with a linked overcurrent circuit breaker. [[BS 7671]]:2008 spells it out. [[User:Suckindiesel|Suckindiesel]] ([[User talk:Suckindiesel|talk]]) 23:44, 15 May 2009 (UTC)

  13. Hi Suckindiesel – very interesting stuff. But can you explain where the energy goes – if you are putting in 1 Mw surely pretty soon the water is going to heat up and boil off? I had assumed that is where the energy went?

    I have seen them at the back of the old Petbow / Cummings Diesel Generator works in Ramsgate with clouds of steam emanating from them?

  14. The design I outlined above for loading a DC diesel-electric loco is unsuitable for the type of AC loads discussed by earlier contributors. BS 7671 (sect 554-03), which deals with the similar Electrode Water Boiler, prohibits use of DC due to the release of hydrogen & oxygen caused by electrolysis of the water. The container itself wouldn’t be used as one of the electrodes either. Rather, single-phase loads would use 2 & three-phase loads would use 3 electrodes immersed in the water. The container should be connected to both ground & to supply neutral using cables of the same CSA as the supply. All poles should be protected by a linked current operated C.B.
    Sizing: It requires 4180 J (1 kcal) to raise the temp of 1 kg of water by 1 deg C. Assuming 75% efficiency, 1-hr loading and a temp rise of 60 deg C (20 to 80 deg C) suggests at least 2 gals / kW of load.

  15. Planning to set up of power management system to improve the generation efficiency of DG sets, How will?

  16. If a generator is run at say less than 20-30% full load for any length of time, then this happens:
    The combustion chamber is not fully pressurized and does not get hot enough. The low pressure means that exhaust gases leak past the piston rings because they rely on pressure to seal them.
    Because the pressure and temperatures are not high, then the mixture will not burn properly, so lots of soot and unburnt fuel leaks past the piston rings.
    this carries carbon, and the unburnt fuel turns to carbon and junk.
    This junk gums up the rings and makes them lead even more.
    The hard carbon scrapes the special grooves that are in the linear and polishes the bores.
    These honing marks are crucial to trap oil, and to enable it to lubricate the piston rings, and for the oil to form the gas seal.
    Once these oil grooves are gone, there is not oil to seal the rings, and so the compression on the engine goes.
    also all the carbon which builds up in the combustion chamber due to the sub optimal temperatures starts to foul the injectors means the fuel spray is disrupted causing even more junk to get into the combustion chambers.
    The end result is only in a few hundred hours, that the engine is wrecked, producing blue smoke from leaking lube oil, black smoke form unburnt fuel.

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