Consumption by Appliances & Equipment
Introduction: Minimizing Electrical Plug Loads
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| While most major energy management efforts have seemed to focus on cutting heating, cooling and lighting costs, many homes and offices have experienced steady growth in their consumption of electricity by appliances and small equipment. Structures with superior insulation, airtightness, efficient heating, cooling and lighting equipment, and sometimes even passive solar features nonetheless often experience significant energy expenses because of this electricity consumption by appliances and equipment. Whether driven to minimize consumer utility costs, to reduce generation-related pollution, to size backup power systems or renewable power supplies, energy auditors as well as consumers can find sometimes surprising opportunities by taking closer look at even medium and small electrical loads, especially those which are constant or occurring in multiples. Replacing equipment with fewer and more efficient units plus modifying operation to reduce on-time can yield substantial savings, whether the goal is simply to cut utility electricity expenses, to reduce negative environmental impacts related to power demand or, in the most extreme situation, to reduce onsite generation and power backup costs.
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This presentation was first composed and presented to Affordable Comfort Conference 2002 in Cincinnati, Ohio, as part of “Short Course FPM11", titled "Reducing Electric Loads: How Low Can You Go?". It is designed primarily for electricity consumers and equipment owners, but also for those practitioners who consult with them, to improve awareness of electricity in general, how it is used and how that use can be reduced or even eliminated. Since electricity is largely “hidden” to most of its users in both its direct nature as well as its consequences, this presentation also includes some discussion of the consequences of electricity production, delivery and use, like air pollution, solid waste and heat.
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| A. Helping the General Public to Understand Electricity |
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| Most consumers and business owners with whom I’ve consulted have only marginal understanding of how they use electricity beyond their major appliances, lighting and HVAC equipment. This is partly because small electrical loads have become much more prevalent and frequent than in the recent past when onsite fuel combustion in furnaces, water heaters, dryers and ranges dominated energy consumption in most small structures. New electrical devices often consume electricity in less obvious ways than old and familiar electrical devices like air conditioners, refrigerators and freezers. For instance, the dramatic increase in availability and frequency of personal digital and computerized devices has been accompanied by increasing incidences of phantom loads, continuous power demands and battery charging. |
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| Homes and offices within typically larger-per-person (or higher occupant-density) floor plans and thermally more efficient modern building envelopes are already reducing their heating energy demand while increasing cooling energy demand. At 3.414 Btu per watt, heat given off by increasing numbers of constantly powered electrical devices is accelerating this transition to greater cooling energy demand, representing a kind of double electricity consumption by many modern electrical devices, since this heat becomes part of cooling load. Transitioning from heating dominance to cooling dominance represents yet another increased dependence on an energy type many people don’t understand. |
Finally, some consumers and designers are becoming more aware of the environmentally questionable ways most of their electricity is produced, but this awareness can sometimes be frustrating without practical understanding about how to reduce electricity use, evaluate its environmental impacts or implement more environmentally benign alternatives like solar and wind which are simple enough to be applied in many average households and businesses. This frustration can be aggravated by the fact that many homeowners and office dwellers feel less able to exert control without outside experts’ advice, service or permission. Indeed, some of my customers appear surprised when they learn they can actually implement on their own many ways to lower their energy consumption and to increase their use of alternate energies, often without too much outside help.
With so few schools in the Midwest USA offering home or business energy education, the onus of this education and information dissemination often falls first on the energy consultant or practitioner. I often meet consumers who are interested in not just lowering energy costs, but also in reducing their environmental impacts and increasing their onsite power generation opportunities. I start these interested laypersons with a brief introduction to terms and concepts related to electricity. Just as it’s difficult to do math without numbers, it’s also difficult to have meaningful conversations with potential customers without them knowing some of the language and relationships in our common energy systems. This is especially true with people thinking about owning and operating some of their own power generation and distribution systems. So in the addendum to this report, I’ve grouped many of the terms, definitions and basic energy information I typically use when presenting to customers and other professionals. If you find a word or phrase in the body of this document which you don't understand, check the addendum for definition or comments which may help you understand better.
Why Some People Conserve or Try To Be So Much More Efficient?
Before focusing immediately on how to reduce power usage by appliances and equipment, it’s appropriate to examine the reasons so-called “early adopters” give for their own efforts to learn about and implement their sometimes aggressive energy saving strategies. I say this because even though most of my customers contact me already interested and motivated to cut their power consumption, sometimes rather dramatically, I sometimes meet people who seem relatively uninterested or unaware about why they should minimize their power consumption or increase their use of renewable energies.
My typical customers first want a super-efficient, maybe even a passive solar home, possibly with some active solar water heating. After that, they want super-efficient HVAC equipment and lighting. Next they want to know how to cut their other energy consumption and how to think about their best solar opportunities. “Why So?” I typically ask them. Below is a short list of reasons I’ve heard. As one of these “early adopters” myself, I share many of these reasons for my own efficiency and alternate energy projects at my home and office. Some of these can sound familiar, while others may not. As consultants and practitioners, we should not only listen to our clients’ motivations and attempt to satisfy them as well as more traditional concerns of our practice, but we should also share those motivations with less motivated folks when we encounter them.
1. Cut energy costs (most important to people with highest energy costs, but very common)
2. Keep utility unit costs lower by decreasing demand for new generation capacity (utilities, especially coops)
3. Make conventional energy supplies last longer
4. Reduce pollution. (environmentalists)
5. Get paybacks or returns on investments to lower future bills (typical business customer motivation)
6. Lengthen power backup duration (important to people dependent on batteries)
7. Improve self-reliance (more important among rural customers and people with less reliable utility power)
8. Reduce power system space requirements (important to aspiring off-the-gridders)
9. Minimize first costs for generation and storage equipment (very important to off-the-gridder)
10. Qualify for special awards or achievement recognition, or “be an example” to others. (More recent)
11. Simplification (there is a growing movement of folks wanting less complication in their lives)
12. More Ownership/Control (some people are tired of not knowing how to control what they are dependent on)
B. Minimizing electricity use by major appliances
A good rule to remember is that appliances and equipment performing the same tasks, from refrigerators to clothes washers, demonstrate very different levels of power consumption. Both the model of appliance and how it is operated can equally affect different levels of power consumption.
Figure 1. EnergyGuide for Refrigerators
For major appliances like refrigerators, the seeming best way to minimize power consumption over its life is simply to buy models with the best energy rating. EnergyGuide labels required to accompany each large appliance in retail stores clearly state the approximate power consumption per year compared with similarly sized other models. The USA website http://energyguide.com offers this same guidance for refrigerators, dishwashers, clothes washer and dryers. See Figure 1. Similar information can be found at the Canadian website oee.nrcan.gc.ca/english/consumer.cfm.
Figure 2. CONSUMER GUIDE TO HOME ENERGY SAVINGS
by A. Wilson & J. Morrill, ACEEE,1998
The American Council for an Energy Efficient Economy (ACEEE) also publishes its periodic CONSUMER GUIDE TO HOME ENERGY SAVINGS by A. Wilson and J. Morrill, which lists only the most efficient major appliances per popular category. See Figure 2. ACEEE lists are particularly useful for identifying those lowest energy users referred to in the EnergyGuide labels.
CONSUMER REPORTS publishes periodic test reports in which energy consumption per task or per year are rated. See Figure 3. Note that Consumers’ Union uses a sometimes more consumer-friendly 5-level rating system that may not be as useful for quantifying energy cost.
Figure 3. CONSUMER REPORTS Buying Guide 2000
For common major large appliances like refrigerators, there seems to be ample consumer and professional access to information in a number of locations to help get the most efficient model, even if sometimes that model must be shipped in from out of state or region. Manufacturers’ own websites can sometimes offer specifications which include energy consumption, but not always.
The most important piece of consumer energy information that may not be readily apparent in ratings like EnergyGuide is side-by-side performance comparisons with models of other sizes and configurations. For instance, notice that the compared refrigerator energy costs shown in the EnergyGuide label in Figure 1 refer only to side-by-side models, while the CONSUMER REPORTS ratings in Figure 3 show comparably sized models of both side-by-side and top-bottom configuration on the same page where casual review can easily see that top-bottom configurations not only typically cost less but also use less energy.
Finally, it’s relatively common to see more than one kind of some major appliance during a home or business energy audit. Sometimes I’ve seen more than one refrigerator and noted that neither were more than half full. In these situations, it’s good advice to most home owners and office managers to consolidate their refrigeration into one most efficient unit. Even two small efficient refrigerators typically use more energy than one medium to large size refrigerator.
Water heater efficiency ratings are similarly easy to understand in reports and lists, unless the water heater is not operated continuously. Unlike refrigerators which are typically left on all the time, water heaters, especially electric tank models, can be turned on and off by their users. Why? Unless there is regular demand for sizable volumes of hot water throughout the day and week, turning off a water heater for long durations reduces standing heat losses and reheat cycling during extended periods of low hot water demand. The less well insulated the tank is and the longer the off-cycle is, generally the greater the savings. Electric water heaters are very simple to control by either a simple user-operated switch or a timer, and electric water heaters are in about 40% of US households. When water heaters are off much of the time and hot water is used rather quickly after their on-cycles, the published energy ratings can be of much less value since they overstate standing losses and reheat cycling.
Consumers with solar water heating systems have additional reason to keep water heaters off during the day. Most solar water heating I see is in houses where there is electric resistance water heating, the most expensive way to heat water at the time of this writing. Electric water heaters are often larger than their combustion cousins because of the typically longer recovery time for electric heaters compared to natural gas or LP units. But this tank oversize is perfect for solar water heating, since the smallest solar collectors are typically 20-40 sf and there ideally needs to be around 2 gallons of tank volume for each square foot of solar collector. In a typical household with mostly morning or late evening hot water demand, it is most efficient to turn off the water heater before the peak use period begins, so that incoming water is not immediately reheated. In the best solar scenario, after a morning of showers and dishwashing, the lowest temperature water is heated by solar while occupants are at work and school. If the water is not sufficiently heated by solar before the next demand cycle (usually evening or the next morning), a timer can turn on the elements to raise the water temperature those last few degrees. Timers typically have manual overrides so consumers can turn on their water heaters for demand outside the normal schedule. The primary disadvantage to having a water heater off during large durations of a typical day is that a use or user may have to wait 15-20 minutes for an unscheduled major use of hot water when stored water temperature is lower than desired. However, many typical midday uses are merely hand-washing, for which warm temperature is adequate.
Most common electric water heater elements use 4.5 kW, so timers can be used to move this electric demand outside a utility’s peak demand period. Some utilities offer rebates for “peak load shedding”, and some utilities install radio-controlled switches to permit them optimum control over this. In commercial installations with sizable demand billing ($/kW or $/KVA), sizable savings can often be found by turning off electric water heaters during the metered peak periods. Most water heater tanks are or can be insulated well enough to provide ample storage of hot water for many hours while they are off, so represents no sacrifice to many common users.
Additional savings are achievable when in a home or business with more than one electric water heater, one can be eliminated or replaced with a tankless unit. Multiple residential heaters are usually sensible only when uses are so distant from one another that separate heaters at point of use result in less standing losses than with a single large heater with very long pipe runs. Recirculating pumps for average size homes and small businesses seldom make any energy sense.
Besides the heater itself and a timer, additional savings can be achieved by reducing hot water temperature to a lower setting, then wrapping pipes and sometimes a poorly insulated tank with more insulation. There can also be savings by shortening pipe lengths from the heater to points of use.
Figure 4. Source Unknown
Finally, there are often opportunities to reduce hot water use directly by eliminating as much hot and warm water use in clothes and dish washers. See Figure 4 to review typical major demands for hot water.
Figure 5. Clothes Washer Rating
Clothes Washer & Dryer ratings and reports are also typically found and reasonably easy to interpret. See Figure 5. However, the energy efficiency of the clothes washer is heavily influenced by whether and how much hot water is used, plus how that hot water was heated, as shown in Figure 6.
Figure 6. ACEEE’s CONSUMER GUIDE TO HOME ENERGY SAVINGS
by A. Wilson & J. Morrill, 1998, page 208
It is usually possible and easy with many modern detergents to wash and rinse most clothes without using any hot or warm water. The highest rated washers don’t even offer hot water wash or rinse options. Clearly in most situations with conventional water heaters and lightly soiled laundry, the least amount of hot water consumed represents the most efficient wash.
In warm wash situations with timer-controlled electric water heater tanks, I advise customers to try to time the wash after the water heater has been turned off AND after the other typical hot water use period has ended. This permits the washer to use the warm water mix which is typically left in the tank.
If hot water is desired and if there is solar water heating, especially in the sunny summer, it’s most efficient to time such washing so that it occurs after a good solar day when there will typically be more than ample hot water in the tank, none of which was heated by electricity.
Regarding drying, the most energy efficient way to dry clothes is on a sun-shaded clothesline outside or in a naturally ventilated room.
When any mechanical dryer is used, the amount of water spun-out of the clothes by the washer has a giant impact on the energy consumed by the dryer. Since electric dryers use electric resistance heat, the most expensive use of electricity, it is especially important to have a washer which is rated for superior water removal. Both CONSUMER REPORTS and CONSUMER GUIDE TO HOME ENERGY SAVINGS typically include this in their ratings.
Dishwasher ratings are also found in CONSUMER REPORTS and CONSUMER GUIDE TO HOME ENERGY SAVINGS. Generally, after selecting the most efficient model, the least energy use is achieved by following four simple rules: 1) Select the energy savings cycles when available; 2) Select no-heat air-dry; 3) Scrape off but do not pre-rinse dishes; 4) Wash full loads only.
C. Electricity use in computer stations and entertainment centers
There are generally fewer useful published ratings on small electrical devices, computers and office equipment. Computers represent growing energy consumption for which many factors influence power consumption, including how power management software is configured, which optional accessories are onboard or connected, how display brightness is set, whether power is turned off continuously and whether there is a UPS (uninterruptible power supply) or other rechargeable battery. And the myriad of office equipment associated with computers have very wide ranging energy consumption from model to model AND type to type.
EnergyStar ratings do not indicate how much power is used when a device is on. A computer monitor bearing an EnergyStar rating powers down to a standby mode only as long as the computer’s power management software is setup to permit this. Typically only laptops come so preprogrammed for maximum energy savings. Many EnergyStar-rated desktops and monitors I’ve examined have not been optimally configured to take advantage of EnergyStar features. Most importantly, an EnergyStar rating says nothing about power consumption by a computer or its monitor when it’s being used.
Although computers and their accessories consume far fewer watts when “on” than major appliances, they can be “on” for longer durations and are much more likely to have phantom loads. A desktop computer and its monitor left “on” constantly, even with full use of all energy saving features, can use as much electricity per month as a refrigerator. Since there can sometimes be more computers in a home or office than major appliances, accumulative energy savings occur when computers are completely turned off when not in use. The most inexpensive way to accomplish this at a typical computer station is to plug all devices into a single-switch-controlled multi-outlet strip, placed conveniently on the desk, not under it.
Notebook computers commonly use 2-10 times less electricity than desktop models. Desktop computers are also commonly connected first to a UPS, which draws a steady current to keep its battery fully charged. Notebook computers usually have internal batteries, so they eliminate need for a separate UPS system, but since they have internal battery chargers, they consume steady power (like 1-10 watts, depending on battery’s condition) when allowed continual access to power. Notebooks I’ve tested have used less such steady power for their internal battery charging than desktop computers' separate UPS units.
Similarly, inkjet printers use far less energy than laser printers, and inkjet copiers use far less energy than high temperature copiers. Some scanners also use far less energy than others.
Table 3 lists running and phantom watts of many common electrical devices and small appliances, some from my own observations and some from HOMEPOWER magazine articles. Notice the phantom loads typical of computer and popular entertainment center equipment. These devices are often “off” most of the time, yet these devices have enough phantom load that, especially when examined in multiples, make substantial savings achievable from switching equipment groupings off with single-switched multi-outlet strips. For instance, a typical 6-watt phantom-load device thought by a consumer to be “off” for 20 hours per day nonetheless uses (0.006 kW x 20 hrs/day x 365 days/yr) 43.8 kWh per year during the time it is off! Even when there are relatively cheap electricity rates, like 7 cents/kWh, this costs $3.58 per year per device. At 11 cents/kWh, the phantom load cost is $4.82 per year. Since typical entertainment centers contain several such audio and video items with similar phantom load, one low-cost (i.e. $5) switched multi-outlet controlling 4 pieces can save 3 times its cost per year even with 7 cents/ kWh electricity. With 11 cent/kWh electricity, one switched multi-outlet can save 4 times its cost each year in avoided electricity cost.
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| Table 3. Measured Or Reported Phantom & Running Loads of Common Devices |
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(measured by me or reported by others as indicated) |
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| Phantom Watts Running Watts |
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| 3-4 750 mhz W98 desktop computer with 17" monitor (accessories all off 100-103 |
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| 9 Speakers and base unit on, but computer off 9-13 |
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| 15 Ethernet broadband internet receiver 15 |
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| 1 ghz W2000 Dell notebook computer with 15" color screen, RWCD, spkrs 25-74 |
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| 8-26 notebook computer ‘off’, but charging a discharged battery |
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| 1 notebook computer ‘off’, with a fully charged battery |
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| 1 3-in-1 HP R60 Officejet print/scan/copy 11-26 |
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| 6 4-in-1 HP 600 Officejet print/fax/scan/copy 24-50 |
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| 0 NEC Silentwriter Laser Printer 400 |
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| 0 Xerox "hot" copier 1100 |
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| Cassette-type phone answering machine with AC-DC power box 3-5 |
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| same answering machine run directly on DC 1 |
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| 6 Portable cordless phone |
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| 16 Projection TV (HOMEPOWER #83 pg.16) 192 |
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| 4 Small TV (HOMEPOWER #83 pg.16) 48 |
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| 5 Sony Stereo Tuner 39-210 |
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| 1 Sony programmable VCR 13-25 |
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| 6-7 Boombox portable stereo with cassette deck and CD player 7-35 |
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| The actual juice, what’s being pushed by the voltage. The more amps pushed thru a conductor, the warmer that conductor gets and the less efficient it is. If a conductor gets too hot, it can cause fire. |
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| The pressure, either DC or AC |
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| The power, the product of volts times amps times power factor. In DC circuits, “volt-amps” is the same as watts. 1000 watts = 1 kilowatt (kW). Voltage is typically made higher for larger power distribution systems to minimize heat and power losses. |
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| The accumulated usage of watts for so many hours. 1000 watt-hours = 1 kWh. All kinds of utility customers are billed per kilowatt-hour ($/kWh) consumed. Renewable energy systems like solar and wind are sized based on their ability to generate power over time, based on expected climate. |
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| That part of an electrical load which is constant, expressed in watts or kilowatts, either of a single load or a system of loads. Large combustion power plants which run continuously are best suited for baseloads. |
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| The maximum demand for watts or kilowatts, either of a single load or a system of loads. On the power system side, power output at any time must exceed total consumer power demand, including the peak load, by at least a little or else brown outs can result. A utility’s combined mix of generation and purchased power are based on its system’s expected peak load, which is basically the sum of all consumer peak demands added together, even if this peak load is not sustained for long durations. Consumer peak load can occur at unique times, as when many consumers turn on air conditioners at the same time. This puts considerable stress on a power suppliers’ ability to maintain adequate capacity, especially if or when peaks grow beyond the suppliers' expectations. A utility which needs extra capacity during peak demand times may not need this extra capacity during non-peak times. At the consumer end, peak load is limited by circuit breakers and fuses. Large commercial and industrial customers typically pay extra charges (priced as $/kW or $/kVA) based on their peak demand, but residential and small commercial customers typically do not pay peak demand charges. In small onsite generation systems with batteries, peak load must be predicted in advance to size batteries, wires and the inverter which converts DC battery power to AC. |
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| DISTRIBUTION & TRANSMISSION LOSSES |
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| This is the drop in power during delivery of power from where it's generated to where it's used. Losses are due to imperfect and long power transmission media which impeded otherwise perfect power flow. Utility distribution losses often average 5-10%. Small onsite power generation with expensive solar power is often designed for very low losses, like 1%, so expensive solar power is not wasted. One of “distributed” or onsite generation’s biggest advantages is reduced distribution losses, simply due to the reduced distance between where power is generated and where it's used. |
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| INSTALLATION & MAINTENANCE |
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| Periodic design, construction, upkeep, fine-tuning and replacement of generation, distribution and storage equipment. This is a regular concern of experienced generators and a new concern of customers interested in their own power systems. |
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| Input energy to produce electricity with conventional generators |
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| Steady erosion of nonrenewable fuels used to generate electricity conventionally |
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| Minimizing possible dangers and harms to workers, users and others from handling & being around electrical components & production |
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| Power consumption not determined or affected by consumer decisions and actions |
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| Power consumption solely determined and affected by consumer decisions and actions |
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| Power consumption by electrical devices when they are turned “off” |
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| Batteries and other means to collect and retain electricity for later or emergency use |
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| Costs added to electrical bills which may be unassociated with energy or the billed consumer |
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| Negative Environmental & Social Impacts of Conventional Electricity
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| Environmental pollution produced to get the electricity. Common emissions resulting from generating conventional electricity include particulates, carbon dioxide (CO), sulfur dioxide (SO2) and Nitrogen Oxides (NOX). These energy-to-pollutant relationships change over time, so because they are often publicly reported periodically relative to specific utilities, it's best to use the most recent data available for particular utilities. As an example, see Figure 7. |
1995 Emissions Summary for Cinergy Electricity
(majority service for SW Ohio, SE Indiana & NKY)
1995 Emissions Summary for Kentucky Utilities Electricity
(majority service for KY Rural Electric Coops)
Figure 7. from Natural Resources Defense Council
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| User demand for the pollution associated with the chosen electrical supplier. Since conventional generation produces emissions for which data are usually publicly reported for specific utilities, an energy auditor can assess a customer's emissions demand as that amount of various pollutants associated with the electricity purchased from a particular utility. |
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| Pollutants and other materials landfilled or stored (i.e. ash from coal burning, nuclear wastes) |
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| Environmental heat given off by electricity generation, distribution & use. Generators typically give off enough heat that they need to be cooled by air or water. Water cooling can dissipate heat as steam into the air or as warm water into a lake, pond or river. “Cogeneration” typically involves the recovery and use of heat from a liquid cooling system. |
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| UNEQUAL DISTRIBUTION OF CONSEQUENCES & PRICES |
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| Unshared ill effects from electricity production, pricing and availability. Power plants are often located so that some customers suffer more of the ill consequences of their emissions, noise and other negatives than other customers. Utilities can also have very different price schedules for different customer types, which result in some customers paying much more per unit of power during the same times as others are paying less. As an example, see Figure 8. |
Cinergy Price & Production Summary 1995
Kentucky Utilities Price & Production Summary 1995
Figure 8. from Natural Resources Defense Council
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| Consumer Electricity Opportunities:
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| Learning about your electricity usage, specifically how much is used by what process or for what device. |
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| Avoiding energy use or substituting non-energy-using procedures for energy-using ones. This is usually the opportunity of lowest consumer cost and greatest consumer control for reducing energy consumption and the costs, consequences and complications of power demand. |
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| Learning about how to use or produce energy more wisely, more economically or with less pollution. Don't assume that one needs to be a professional or expert to become energy-educated. |
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| Getting more work done with less energy input and waste. |
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| Becoming more influential over one’s electricity production, pricing & consumption. This concern was one of the driving factors for smaller consumers from coal and nuclear powered utility areas planning for deregulated electricity markets, for instance, thinking that to be a good way to obtain more local access to power with less environmental impacts. |
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| Investing in and owning more of one’s own electricity production systems and consumption hardware. This is one common interest of people who choose to own their own power systems, to be “off the grid”. |
Copyright 2002 - 2005 by:
John F. Robbins, CEM
3519 Moffett Road
Morningview, KY 41063-8748
Phone: (859) 363-0376
E-mail: johnfrobbins@insightbb.com
