Underneath the energy radar
A power analysis expert to advise on often forgotten energy saving hardware can cost less than taxation advice and save you the same order of money, writes DAVID CARDOZO.
Reducing electricity costs in the current climate is a high priority for many organisations. The low-hanging fruit of negotiating better tariffs, and obvious energy saving measures such as high efficiency lighting, movement detectors and insulation is therefore assumed to have already been taken care of.
In this third article in the series on managing electricity costs, hardware solutions get a guernsey. These usually fly under the radar of general business management, being the province of technical publications, but there’s every reason to understand their significant saving potentials.
Return on investment (ROI) is a guiding measure in the evaluation of available savings. We look at switchboard monitoring, harmonic reduction and power factor control. The latter was examined in an earlier article, but the technology deserves more attention.
You do not need a background in electrical engineering to get some value out of the information presented. The economic benefits are the headline items, and the descriptions of hardware are sufficient to provide a basis for discussion with engineering services managers, consulting engineers and other technically qualified folk.
There is also voltage control as a matter of importance. However, this is raised as an item to keep a watch on, as it is still an area of developing technologies.
The hardware solutions presented fall into the following classifications:
- continuous monitoring to spot in explicable consumption
- improving energy efficiency, and
- benefitting from demand tariffs.
Revenue electricity meters record gross consumption and cannot provide any clues as to where and when parts of a facility are subject to suspiciously high (or low) consumption patterns. In order to get a handle on this, you have to contemplate an unrealistic solution: a multiplicity of electricity meters.
There’s a smart way to avoid this – and have the benefit of all the data, on all circuits, plus warnings when a high or low consumption, or equipment problem is detected. This illustration shows the heart of the monitoring system.
Illustrated are three circuit breakers of which your facility may well have hundreds. Notice the grey box on top of the circuit breaker, with wires passing through small apertures(sensors).Theboxisacurrent sensor, and you can have well over 100 wires (individual circuits) monitored by one communications module.
Installation is simple, and no modifications to distribution boards are necessary, as is evident from the photo of a typical installation (the area enclosed by the red lines shows a 12-circuit current and power sensor module). Energy management software tailored to your needs provides information, including:
- high current and power usage in display refrigerators
- excessive power usage in air-conditioners
- power consumption in multi-tenanted facilities
- power consumption in serviced apartment and office complexes, and
- granular power consumption in production lines (bottling, packaging etc).
In addition to energy usage, there are other benefits, such as equipment malfunction and electricity theft or detection of unauthorised use of power. In outline, a motor developing problems and posing a business interruption or fire risk will show up with tell-tale signals, current imbalance being a strong indication of problems to come. This can all be conveniently flagged by way of ‘exception reports’.
A monitoring system as described can have an effective payback of months by virtue of the ability to allocate costs accurately
– one example being that of common area cost allocation in serviced apartments and shopping malls. The list of applications is close to endless.
The average electrical installation of a business, supermarket, hotel or hospital etc comprises a main switchboard, often a separate switchboard for the mechanical services like climate control and elevators, and a large number of sub-distribution boards servicing individual floors and so on.
All of this wiring loses you energy – basically dollars spent for zero benefit. The loss inside your premises can easily be five percent. Not all of this is easily recoverable but, depending on your willingness to outlay some CAPEX(capital expenditure), the losses can be reduced to half or even less.
By not allowing ‘useless current’ to circulate in the wiring, less energy has to be purchased. Known technically as harmonic current, it is an unfortunate feature of high efficiency lighting, air-conditioners, freezers, commercial fridges, pumps… you name it.
This useless current component does nothing for you, but heats up your electrical installation. Devices known as active harmonic filters perform the task of ‘filtering’ the useless current out of the wiring system. In short, the equation to consider is the cost of the filters versus the savings in electricity through increased efficiency.
The trick is in the positioning of these filters. For example, if installed at the main switchboard they save you nothing and only make your network provider happy, since another task of active filters is to improve the network’s power quality. However, if installed upstream of the main switchboard, all the wiring between the switchboard and the active filter is ‘clean’ of harmonic current and its consequent energy loss. In other words, you get more bounce for your energy buck.
Determining the savings potential of active harmonic filters is the work of a power analysis specialist. Depending on the complexity of your installation, a survey need not take much time and, based on the availability of good documentation of the electrical installation, can be completed in a day or two.
Demand and kilowatts are almost the same thing for only relatively few electrical installations. Most, and yours included, require more current from your provider than is strictly needed for your energy needs. The relationship between demand (measure in kilovolt-amps, kVA) and kilowatts needed to power your lighting, motors, etc is indicated by ‘power factor’, a ratio of the two parameters. A power factor of one (1) indicates an ideal situation in which kVA and kilowatts are identical values.
In practice, power factors are more likely to be of the order of 0.9 and lower. As explained in an earlier article, low power factors are a headache for network companies because they require beefing up of their wiring simply to get the kilowatts to your premises. These days more and more network providers and energy retailers are putting into effect a financial incentive to improve power factors towards 1 as much as possible by charging customers a monthly demand charge in addition to the kilowatt-hours billed. Even smaller consumers, those with monthly bills for energy in the region of $2000, are being charged for demand.
Correcting the power factor to 0.99 by employing power factor correction hardware at your installation can be a smart move, with typical paybacks on investment of the order of two or three years. Your installation along with the bulk of medium to smaller consumers will be a so-called low voltage (LV) type. These demand a power factor corrector capable of individually correcting the power factor of each of the three phases providing energy to your installation.
ENERGY, VOLTAGE AND A WORD FROM SOMEONE IN THE TRADE
Richard McIndoe, the former CEO of Energy Australia, expresses surprise at the lack of emphasis on energy saving measures, whereas the spotlight on electricity providers’ pricing structures is unrelenting. McIndoe’s new business, Edge Electrons, focuses on hardware for energy saving, including not only very nifty power factor correction gear designed for low voltage 415/240 volt customers, but also a new technology, voltage regulator.
Too few volts, and the lights go out; too many volts, and you pay more for your energy than you need to. A five percent over-voltage translates to 10 percent more power than needed, the relationship being that power is proportional to the square of the voltage.
The new technology from Edge Electrons provides a virtual lossless voltage conversion to constant voltage for domestic installations, and will shortly be offered for smaller businesses, and larger three-phase domestic solar panel installations.
McIndoe says that investing in energy saving solutions rather than waiting for prices to come down is the smart way to respond to the uncertainty surrounding the electricity supply situation in Australia. He ought to know!
David Cardozo is a Melbourne-based energy writer and regular contributor to FM.
This article also appears in the February/March issue of Facility Management magazine.