Energy Demand: Knocking Off the Peaks

by Dan Schafer

(Production Manager for Fine Enamels, Thailand)

One day about two years ago we had an interesting electrical problem. We have become used to getting our power shut off, and having to figure out what to do with our workers who are sitting by machines that have suddenly gone dead. In fact it is a frequent enough event that sometimes we don't even need to tell the workers. They just get up and head for the shipping room where we've had them help do all sorts of low skill assembly or packing jobs. But this time it was strange. Our lights went dim and our motors slowed and stopped but kept humming. If you live in California you probably know that what I'm talking about—a brown out. It is actually a very dangerous situation for most equipment. The voltage has dropped below the normal range. And if you don't quickly shut your motors and other sensitive equipment down there can be serious damage.

In fact it isn't just California and Thailand that suffer brown outs. The main cause is a defensive measure taken by electric utilities that can happen anywhere in the world. Basically their consumers' total electricity use is approaching their production or supply capacity. If they can't quickly source some more generating power, one way to cut consumption to protect their generating equipment is to crank down the voltage. Since power consumption, watts (also measured in kilowatts or megawatts), are the product of a simple mathematical equation of volts times current (amps), consumption automatically goes down. Then, of course, anyone who has vulnerable equipment (and knows it) shuts it down to avoid burning it out.

Why Brown Outs?

There are other reasons for brown outs, such as voltage loss over long runs of wire that affect particularly the consumers at the end of the run when those before them on the line are using up the capacity of the wire. But our concern here is mainly for why electrical utilities get into this problem, and what the normal solution to it is. Basically when the power grid and generating plants were set up or updated there were records and calculations that suggested what the maximum demand was likely to be a projected number of years ahead. The planners then made sure that they had adequate generating facilities or subcontracted sources to meet that demand. But now the situation has changed. Either electrical consumption has grown faster than projected -- or financial, managerial or political problems have delayed normal expansion of generating capacity. Really when it comes to solving the problem, from the electrical utility's point of view they haven't much choice. If they are committed to meeting their customers' demand, they have to invest in more power supply.

If there were some other way it certainly would be cheaper for the electrical utility and in turn for their customers. Of course eventually any equipment must be replaced. But if it can be replaced in an orderly way, when it has finished its useful life, rather than under pressure of having to gear up for an unexpected or unplanned bulge in electrical demand, it is more economical for everybody.

Hold on New Power Investment!

I want to suggest another way. This other way is attractive, not only to the electrical utility who can put off their new plant and equipment investment, but also to the consumer who can save a lot of money on his electric bill.

Utilities Getting Wise

{short description of image}

First let us look at how we have already been set up to solve this problem. At some point electrical utilities got wise to the fact that they were having to commit capital and that capital's earning power to holding excess generating capacity. That is, it is excess capacity most of the time. But there are times, like California hot summer afternoons and evenings when that "excess" capacity gets used up. Since holding that "excess" capacity costs the utility money, they decided to try to recoup that money through charging those (us) who drive up the need for that capacity. So a "demand" charge evolved. Basically most industrial users and some domestic users pay an extra calculated fee for the highest level of use they had in each monthly billing period. That fee can amount to considerably more than the basic kilowatt hour charge. They, the electrical utilities, created a strong incentive for us to keep our "demand" down.

Users Getting Wise

So when we, for our part, got wise at our factory here in Thailand, we started trying to tackle this problem of demand. The first thing we looked at was related to a conspiracy theory of sorts. Right or wrong this is how it went. At the top — electrical supply in Thailand is all government controlled — someone decided that adopting this demand charge payment calculation was a good thing. They may have even thought it for the right reason — creating an incentive to keep demand down. Giving them the benefit of the doubt at that level, we were skeptical about how far that altruistic sentiment crept into the practical implementation of collecting money from customers. After all, money is money. And what bureaucrat anywhere keeps sight of the big picture when the opportunity to keep revenues flowing in is so obviously before him? So given our experience of such frequent, seemingly arbitrary cutting of our power in the early years of our factory here, we suspected that might be a good way for them to make sure our demand was good and high. After all, when the power got cut all the motors and lights and air conditioners and heaters were still switched on. Then restoring the power makes them all start up at once. That creates a pretty good spike in consumption. It could be they were neither that malicious nor perhaps that clever — just disorganized. And to keep the record straight, the consistency of our power supply today is many times better than even five years ago. But it was a good place for us to start solving the problem. So when we decided to upgrade the distribution panels at the point our power entered the factory we installed a delay system on four major circuits. So now when power supply is restored only one major circuit is started at one time. Then after a delay of about 30 seconds when the motors and compressors that have started are now drawing only what they need to run as opposed to the high amount they need to start, another circuit switches on, and so on until everything is back up running.

Schedule Power Use

That was the first step. But we were still getting high demand charges. Another practical thing we could do was to look at our manufacturing schedule. In fact we have two or three major processes that don't have to be done everyday, all day long. Two of them, in particular, are big power users that only have to be done two or three times per week. So we really only had to manage the manufacturing rhythm of the factory to not let electroplating and metal casting be done on the same day. Of course when we have deadlines to meet we at times have to juggle to alternating one job in the morning and the other in the afternoon. But the principle definitely helped reduce our demand.

{short description of image}

Find Out Where You Are Missing It

The frustrating thing was that we never really knew objectively how much electricity we were using at any time. I suppose we could have stood by the electric meter to see if the little demand needle bumped up. But not only would that have been tedious and time consuming (all day long every day!), but by the time the needle moved it would have been too late to correct it. We found that for the price of half a month's electric bill we could get a digital meter that could feed into a computer data of every characteristic of our electrical use that we could ever want to know at any moment in time. It could also, every fifteen minutes, take note in its own memory our demand on each phase. Actually it could hold on to that data for 24 hours a day, every day, for over a year. We could download it to the computer anytime we wanted. I could convert the data to a spreadsheet and then a graph and look at it. I could study where our peaks and troughs were appearing during the day and compare that to what equipment I knew we were using.

{short description of image}

How to Control

The meter also had two relays that could be preset to shut down circuits connected to them at preset values of demand consumption. Now that was a wonderful step forward, because we could connect things like large air conditioner compressors to those relays, and actually have something that automatically started to control our demand.

So between the ability to analyze what was happening and as a result make equipment use schedules and the ability to automatically knock the peaks off our consumption, we were making real progress. We (and consequently the electrical utility) were no longer just the objects of uncontrolled events as regards our electrical demand. We had begun to bring some order into it. And really that kind of order is progress for everyone. But we still had more progress to make, and I'd like to discuss that development next time.

Return to Table of Contents