Energy management in a business context

[etienne]

Hello,

After doing energy optimisation for 8 years now, I wrote, first in french
than made a fast translation in English
of a document with all my professional experiences regarding energy optimisation.
https://bayenet.jimdo.com/energie-et-entreprise/

Comments from sidd (please see first reply) have been integrated in the English version. My e-mail has been removed so that my mailbox is protected if the document in shared. There is a reference to my personnal page which has a contact page.

I thought this might interest you all.

Thank you for all comments, also regarding spelling and gramatics.

Best regards,

Etienne

[sidd]

Some points

1) Reducing temperature in hot water systems has risks
2) Power and efficiency are not necessarily opposed
3) Discount rate is crucial for financing of energy reduction investment

Perhaps some expansion on these points might be useful. And inclusion of case studies might help.


sidd

[etienne]

Hello sidd,

Thanks for the comments.

Some points

1) Reducing temperature in hot water systems has risks

Well, only if we talk about drinking and sanitary water. The water that turns in the radiators can have a very low temperature. Floor heating can be done with water under 30°C/90°F.

For the closed circuit cooler, we use a lot of chemicals to keep water "clean", but last time I informed myself (already a few years ago), the trend with new equipment was to use water only when really needed - in our context, with outside temperature above 20°C/68°F. Our system was built in 1998, it stops using water when freezing and fills up again when outside temperature is above 15°C/59°F. We need a big temperature difference between filling and emptying because the tank contains a lot of water  that we don't want to waste.

2) Power and efficiency are not necessarily opposed

This is a comment that everybody does. A small motor on a car will get a better fuel efficiency than a big motor on the same car. In Germany, there was a joke about a military armored vehicule that had the best fuel efficiency on earth per kilogram of vehicule, but the fuel efficiency per kilometer was extremely bad. If you oversize your equipment, you get a lot of power, maybe efficient power, but loose business related efficiency.
Of course, if you replace a light bulb by LED, you can get more lumens for less energy, but you could get the same amount of lumens for even less energy.

3) Discount rate is crucial for financing of energy reduction investment

Could you be more precise ? I don't get on what applies the discount (interest rate ?). The problem I had most of the time was the ROI, it was often higher than 2-3 years which was too much for a non strategical project to be accepted. This is why I said that energy efficiency points out a long term strategy and proposed a small energy optimisation budget were ROI requirements wouldn't be so hard to meet.

Perhaps some expansion on these points might be useful. And inclusion of case studies might help.

I agree. When I first wrote the document, my idea was to use it for public presentations, so examples could be given directly. Including case studies is a lot of work and I don't have enough examples to really write a book on this subject. Maybe in a few years.

Thank you very much for your comments,

Etienne

[sidd]

Re; Case studies

http://www.utilitydive.com/news/inside-the-first-municipal-solar-plus-storage-project-in-the-us/421470/

Re: risk
Agreed that risk is water physics and chemistry. I have run antifreeze in temperatures as low as -20C, but one has to carefully monitor and balance.

Re: discount rate
Agreed that it applies mainly to longer term investment.

Re: Power and efficiency
Agreed that reduction in use of energy/power is first priority.

sidd

[etienne]

Hello sidd,

Thanks for the article. It is very interesting.

http://www.utilitydive.com/news/inside-the-first-municipal-solar-plus-storage-project-in-the-us/421470/

In Luxembourg, the strategy seems different.

We have a very integrated electrical network (also with Belgium and Germany), and peak load is produced with a 1096 MW water storage with electrical conversion http://www.seo.lu/Hauptaktivitaeten/PSW-Vianden/Vorstellung (you can look for images putting "VIANDEN SEO" in google) so storage is not so much an issue with solar because peak load of the country is in the day. Luxembourg was always very good at finding and building added value systems.

Of course, power outage is an issue, so power supplier propose to install batteries and more on the industrial sites as an added value service. It also allows them to manage peak load on the network and reactive power.

In Luxembourg, you will also find many diesel to electricity generators. We are renting a floor in a facility that has a generator just to support the elevators and the pump for the fire protection sprinkler system. One of the saving we did on the headquarters was to reduce the monthly test from 1 hour to just 1/2 hour, excepted a longer yearly test during transformer maintenance.

Bye,

Etienne

[sidd]

I have found that large diesel engines  take about 30 minutes to come to temperature, and i like to run them for 15 minutes with no load before shutting off. When i am testing electrical backup, i run loaded for 30 minutes, mainly to check voltages and currents on each bus. So that already takes me over an hour. But i only check once every quarter, rather than monthly.

sidd

[etienne]

We have an electrically pre-heated engine because it has 30 seconds to take the load of the IT room and climatisation. When I talked of 30 minutes, it is the time where the load is carried by the generator, it runs without load afterwards, but this is automatically managed, if I'm right about 5 minutes. It is not so large, around 700 kW, I don't remember if this is the power of the engine or of the generator.

I have another question about batteries. Personnaly, I don't like it, it requires regular controls and doesn't really warn before having problems. I know we need it for storage, but I always tried to minimise the quantity in use and to do it in centralized/protected areas.

Nowdays, electrical buses are totally in, for example https://robertscribbler.com/2017/01/12/the-electric-vehicles-are-coming-global-sales-likely-to-exceed-1-million-during-2017/, but I would really prefer trolleybuses. I believe that they must be cheaper, maintenance must be cheaper, and that you must have a much more regular load on the network. I don't understand how people can talk of sustainability with such technologies.

What do you think ? Am I totally wrong ?

Etienne

[sidd]

"We have an electrically pre-heated engine because it has 30 seconds to take the load of the IT room and climatisation."

Excellent. I have electric oil heaters on the diesel sets,  but only switch them on when temperature dips below 10C or so, mebbe i should look at running them all the time, and hotter.  For critical load, i have put in flywheel motor generator sets which are always spinning from grid AC. When grid power fails the flywheel drives the generator for switchover power, and supplies torque to start the diesel which takes typically under 10 seconds. The diesel is not happy for 15 minutes or so in cold conditions, even with oil heat on.

(Perhaps I should point out that the buses i was talking about were the fat electric connectors supplying stationary building load, not public transport)

In general, I find batteries very well suited to certain applications. Careful monitoring is necessary, and companies like Tesla and Sonnenbatterie have that well integrated these days, sure beats checking electrolyte levels and voltages on lead acid like in the old days. I have been looking at putting in batteries for some of the flywheel applications, but i haven't jumped yet. I think batteries have got so much better, they are actually competitive. As far as sustainability goes, they are certainly better than internal combustion of fossil fuels for transport.

Not perfect, but small steps get you started.

sidd
sidd

[etienne]

Well, we never had flywheel generators for cost and maintenance reason. The only ones I know that are installed in Luxembourg are in containers that can easily be connected so that an exchange is posssible when major maintenance is needed. (if I'm right every 5 years). I know a bank that took them out when the first mainteance was needed.

Our strategy is to have an IT room that can survive 15 minutes without cooling, which is much more than enough for the generator to start and the cooling to restart, so we only need UPS for IT equipment, and batteries are just perfect for that, even when working the old way. This 15 minutes without cooling is also very usefull for all kinds of maintenance (everything related to fire protection and extinction, cracs...).

With our pre-heated generator, temperature never drops very low around the generator.

Regarding batteries, improvements must have been prodigious. The first installation I saw was stinking and had strong requirements regarding temperature, ventilation, space available... the second one was already much better, but AC was still required. Now you can have a lot of power in a car or a bus (important load changes) without too much fire/safety and temperature control.

Bye,

Etienne

[etienne]

Hello,

sidd's comments have been integrated in the English translation of the document. See topic opening message.

Thanks, best regards,

Etienne

[etienne]

Hello,

I had lunch today with somebody of the electrical maintenance company, so I was happy to ask some questions and can share the information here.

LED is very good inside buildings, but they have projects in industrial areas where they are not so weather protected and they have problems. Electronics don't like too much heat and cold excepted if it is specially built for it. At my home, all supermarket LED bulbs that are outside of the house are not working anymore.

Flywheel motor generators are very good if you need a lot of power (in MW). In that case, batteries would take too much space  and the flywheel becomes very efficient. Batteries UPS have the virtue that you don't get any of the problems of the external network in your IT room, electrical networks are totally separated.

Automotive electrical systems including batteries don't have much in common with IT ups. IT ups are built for a stable load and only support more than 150% of nominal power for very short times (110 % is the recomended maximum). Starting an electrical motor requires too much amps for an IT ups.

Best regards,

Etienne

[sidd]

I am seeing very large outdoor LED deployments in midwest and eastern USA. Traffic lights were the first apart from some problems with snow build up (LEDs dont generate as much heat) which were fixed quickly. I would say about 50% or the parking lots used by my drivers have gone to LED. So i think weatherproofing LED fixtures is mostly a solved problem considering the huge swings in temperature and humidity in the midwest.

[sidd]

Re:flywheel moto-gen

I have used them for loads as small as 150Kwatt, they are not all sized for megawattage ...

[etienne]

I am seeing very large outdoor LED deployments in midwest and eastern USA. Traffic lights were the first apart from some problems with snow build up (LEDs dont generate as much heat) which were fixed quickly. I would say about 50% or the parking lots used by my drivers have gone to LED. So i think weatherproofing LED fixtures is mostly a solved problem considering the huge swings in temperature and humidity in the midwest.

Hello sidd,

I totally agree, but this is a warning about supermarket LED. Normal LED lightning systems (2500 lumens) for professional use cost around 250 EUR here, but in the supermarket it could be under 100 EUR, so you can't expect the same quality. Furthermore, when you put your light bulb outside in a glass container to protect it from rain, it is just like in a solar stove which is not soo good. LED works, but minimal conditions are needed.

[magnamentis]

I am seeing very large outdoor LED deployments in midwest and eastern USA. Traffic lights were the first apart from some problems with snow build up (LEDs dont generate as much heat) which were fixed quickly. I would say about 50% or the parking lots used by my drivers have gone to LED. So i think weatherproofing LED fixtures is mostly a solved problem considering the huge swings in temperature and humidity in the midwest.

Hello sidd,

I totally agree, but this is a warning about supermarket LED. Normal LED lightning systems (2500 lumens) for professional use cost around 250 EUR here, but in the supermarket it could be under 100 EUR, so you can't expect the same quality. Furthermore, when you put your light bulb outside in a glass container to protect it from rain, it is just like in a solar stove which is not soo good. LED works, but minimal conditions are needed.

confirmed from first hand experience. i changed my entire illumiation to LED from a not that cheap market "Bauhaus _ a german chain" but they were clearly sales bulbs (probably a bad series ) from a renown manufacturer (Osram) and guess what, they ALL (100%) failed withing 4 months of use. for now, until even low cost series are working normally i will wait before i spend many 100 bucks to replace all my illimination just to find me do it again within no time.

[charles_oil]

Is bulb life the biggest scam ever? 

Bulbs are advertised with thousands of hours life - but many fail quickly - but can you be bothered to keep receipt / carton and take it back ?

[in4apenny]

Is bulb life the biggest scam ever? 

Not in my experience, been running them at home for approx 2 yrs & no failures yet. There's a mixture of bulbs , supermarket cheapies & branded working in a variety of situations ie dimmer/frequent switching & long on time, all running from  a pretty stable 240vac mains supply.

I believe the problem is mainly with the rectification circuit , the bit that gets hot in the base of the bulb ( don't use the transformer fed bulbs so can't comment on them) & keeping the bulbs ventilated is beneficial.

[etienne]

I confirm that I only had problems with supermarket bulbs, even with a few bulbs inside the house. At work, it was always good, and we have replaced at least 100 MR16 bulbs with LED 2 or 3 years ago.

A friend sais that the problem is the cooling. Normal bulbs like normal electronics should not go above 40°C and that is not always easy to go.

At home, I have better experiences with complete lightning than with bulb replacements.

[sidd]

Re: LED lifetime

Should point out that the contractors I know who do large commercial/industrial installs usually also contract for maintenance, and have to eat the costs if the product/install is bad. The larger installs are also tied to savings in electric consumption, with penalty clauses for nonperformance.

So quite a far cry from picking bulbs off retail shelves and slapping them in. I suggest talking to contrators and buying surplus LED fixtures from them, or getting them to bundle your order with theirs. Much better pricing and quality that way in my experience. And they can give you tips on install and manufacturer.

Another interesting thing i see is the huge improvement in color balance in LEDs. That is very important in certain applications like food display on supermarket displays and dining areas, clothes closets and makeup vanities. No on wants to eat odd colored food, dress in odd color combos or apply weird makeup ...

sidd

[etienne]

Re:flywheel moto-gen

I have used them for loads as small as 150Kwatt, they are not all sized for megawattage ...

Hello sidd,

What was the load behind the flywheel motor generator ? I only know IT applications. Maybe that makes the difference.

Best regards,

Etienne

[sidd]

150 kilowatt

[etienne]

Hello sidd,

My question was what kind of load ? Electronics, motors, heating device ?

Bye,

Etienne

[sidd]

Major load in that case were pumps and temperature control heaters (industrial process) There were control electronics and lighting and a few other motors and odds and sods, but the first two were the biggest.

[etienne]

Hello,

I got this morning the confirmation that cars are normaly built with DC motors, so the whole conception has nothing to do with UPS. Looks like to put a motor on automotive batteries would require a DC motor.
For motors, the main advantage of AC power is that you would save sqr(3) in current for the same power, which means lower copper diameters, which doesn’t matter for cars because cable length is very short. I don’t know much about DC motors, but building a DC system in order to have it on automotive batteries seems more like an experiment than like an industrial project, so I guess this is why Flywheel diesel generators are very good in that context.

Maybe if you can integrate solar PV panels, the experiment could be very good and have a very efficient result, but I still believe that it wouldn't be a project that can be realized without suprises.

Best regards,

Etienne

[sidd]

" Looks like to put a motor on automotive batteries would require a DC motor."

Not if you have a good inverter. I have run AC motors with supply from batteries converted to AC by inverter. Inverter efficiency is reaching well over 90%, so major loss is storage loss.

[etienne]

Hello sidd,

You are right. I read a little bit on motor management on Wikipedia because I don't have too much experience with motors. I didn't know that there were so many solutions to limit starting current on AC motors and how a speed variator is built.

With motors, can you run with your UPS on by-pass, or with a load transfer switch ? Just switching on batteries when network is in trouble ? In that case, you don't have so much the starting issue and you avoid too many peak loads on the inverter. There could even be a security check in order not to start a complete industrial process when there is a breakdown of the network (at least to wait until the generator has started), I guess that in most cases, it is the process that needs to be protected, not the starting of the process. Well, here we enter in specific configuration and it is not so usefull to make therory without real example behind.

In our cooling system, we have different power source for regulation (UPS protected) and for power systems (heat pumps... are diesel generator protected). When network breaks down, we first wait 30 seconds to see if it comes back, than the generator needs 30 seconds to take the load. We have just one pump that has sometimes starting problems after a power cut, so a small UPS with a load transfer switch would be a perfect solution, but I don't know if this could work, the supplier didn't suggest it. It's a redundand system and it is not each time problematic, so we need at least 2 or 3 power cuts to get in trouble, the shorter cuts are the worst. Problem was solved with specific training, but in case of major trouble, it's not sure what problem will be handled first by the technical team.

Bye,

Etienne

[sidd]

For motor loads spinning up for dead halt,  you need to oversize the UPS and inverter, use soft start on the motors and if necessay, stagger turn on of motors so they dont all spin up at once and give you huge combined inductive kicks. But in my typical applications, the motors never stop spinning, the load is transferred fast enough that the motors dont spin down.

As you say, without detail is hard to advise. If you are starting from dead halt, do soft start capacitor, and start with no load on motor. Oversize the UPS and inverter, make sure you are getting clean sinewave. Stagger (sequence) multiple motor starts, 20 second delay to the start of next motor after preceding motor has spun up and is under load is a number i have used before.

sidd

[etienne]

Thanks for the information. We have to start the motors because we have a redundand system that alternates each week in order to insure permanent cooling. If we get an agreement for UPS protection, we will measure starting current and size the UPS according to that measurement. It’s probably the best thing to do. What we want to protect is not so big that the size of the UPS and the of the Inverter would be a problem.
Thank you very much,

Etienne

[sidd]

For motors, 3 times peak load current equals inrush current for start from dead halt under load is a good rule of thumb. Depends on load torque profile vs rpm, of course. Size inverter and UPS accordingly.