A district energy system produces steam, hot water, or chilled water in a central plant. The steam or water is then piped directly to individual buildings for heating, air conditioning or water. Under this system, individual homes do not need their own boilers or furnaces, chillers or air conditioning units. It has several advantages: District energy is energy efficient, reliable, and convenient for consumers, decreases building capital and life cycle costs, and allows for more flexibility in architectural design. Localized systems for heat and cooling production are common in Western Europe and also offer potential for energy efficiency in third world countries. Appropriate policies are crucial to the success of these systems. District heating can easily incorporate renewable energy, including biomass and waste products. They can also recycle industrial waste heat. District heating currently accounts for 30% final energy consumption in Russia and Belarus. Most district heating provides combined heat and power (cogeneration), a highly energy efficient option. District cooling, which is underrepresented in transition economies, utilizes absorption technologies.
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According to the EIA, appliances account for 64.7% of electricity consumption in the average US home. However, increasing efficiency for appliances is hampered by the fact that TVs and computers are not covered by federal standards. As a result, the EIA believes that computers and related equipment will be a strong driver of residential consumption and will increase at the same rate as population growth. This a scenario that is likely to be witnessed in the rest of the developed world, as home computer use grows.
In the US the DOE funds some state rebate programs for consumers purchasing Energy Star-qualified appliances. Though some states have already closed their programs, many others open throughout 2010 and will continue until February 2011 or when all funding is spent. Additionally, the DOE has recently stepped up their enforcement of appliance efficiency standards
Often appliances are labeled to show their energy use and environmental characteristics. The US Environmental Protection Agency offers the Energy Star label, which indicates the appliance has met specific government standards for energy efficiency, performance, reasonable return on investment through reduced energy costs, and other criteria.
In China, as populations urbanize and homes gain electricity, use of residential appliances is expected to increase significantly. According to a Lawrence Berkeley National Laboratory (LBNL) June 2009 report on residential energy use in China, 21% of household electricity consumption in China comes from air conditioners, refrigerators, clothes washers and dryers, and televisions, while 9% comes from lighting alone., Clothes washers, air conditioners, and refrigerators are all subject to mandatory efficiency labeling in China,. Efficiency labels range from 1 (55-65% minimum standard energy usage) to 5 (90-100% minimum standard energy usage.) China also has mandatory efficiency standards for a number of household appliances including irons, rice cookers, fans, dehumidifiers, and televisions, and voluntary labeling for microwaves, water heaters, computers, and a number of other appliances, according to the Collaborative Labeling and Appliance Standard Program.
A March 2010 report by the European Council for an Energy Efficient Economy found that in the fifteen countries that joined the European Union between 1995 and 2006, sales of televisions rose nearly one-third by 2006. In the twenty-five countries that joined the EU by 2004, researchers estimated that each household would, on average, have two televisions by 2010. The EU has set a goal to have 80% of all households equipped with a smart electricity meter by 2020, and has mandatory and voluntary energy usage standards and labels for several appliances, among them refrigerators, freezers, clothes washers, dishwashers, ovens, room and central air conditioners, space heaters and lamps, according to the Collaborative Labeling and Appliance Standard Program.
Smart appliances
“Smart” appliances take another step towards energy efficiency by automatically synching high energy use (such a defrost cycle in a refrigerator) with the time of day energy rates are at their lowest, and going into energy-saving mode when rates are highest, based on signals picked up from utilities. General Electric Appliances and Lighting’s line of smart appliances include smart refrigerators, as well as microwaves that reduce wattage during peak hours, dishwashers that delay starting cycling until rates are low, and clothes washers and dryers that delay starting until off-peak times. Smart appliances can be wirelessly linked together, along with smart meters, by home automation technologies for maximal efficiency.
GE has several smart appliance pilot projects now under way. In the US, the Vineyard Energy Project on the island of Martha’s Vineyard, Massachusetts is testing management of smart appliances from a central control room. Energy managers at the central location manage the electric load of the appliances in the home, restricting their operation during peak consumption periods when the grid is under strain and electricity prices are high. For example, the central control room might reduce water temperature slightly of home hot water tanks during peak periods through remote communication with the appliances. The program allows 50 consumers to buy, at cost, the smart appliances. GE hopes to see how consumers react to outside management of their appliances and how this changes their energy consumption patterns.
GE also has undertaken a smart appliance pilot project in Masdar City in the United Arab Enmities, which is striving to become a zero emissions city. Homes equipped with demand response-enabled refrigerators, cooktops and clothes washers/dryers receive signals from the grid, which simulates peak energy usage periods. The energy manager and smart appliances respond to real-time grid signals and customize the appliances’ actions to save energy and reduce demand on the grid. Because the appliances measure their own energy consumption, the program will supply a level of detail about energy consumption patterns not typically available. Indeed, traditionally the utility meter measures only overall household energy use.
GE also has a smart appliance pilot underway in conjunction with Louisville Gas & Electric, a US utility in Kentucky. GE employees are participating and have thus far reported peak energy savings as high as 20% The GE appliances work by receiving a signal from the utility’s smart meter which alerts the appliances when a peak period occurs. The appliances are programmed to avoid energy usage during that time or lower their wattage. Customer have the choice of overriding the program if they want the appliance to operate as if grid conditions are normal and no energy reductions are needed.
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Transportation technologies have improved significantly in the last several years. Vehicles are being built with increasingly efficient power-train systems and light weight materials. Hybrid electric technologies are growing in market penetration. There is likely to be even greater levels of fuel efficiency in vehicles over the next two decades. In the US, for example, fuel economy will increase by 40% by 2030, according to the NREL. In turn, fuel economy will create consumer savings of about $300 to $500 each year, according to the US DOE. Much of the savings comes from use of hybrid, electric, biodiesel, and other alternative vehicle technologies.
Under current technology, only about 15-20% of the energy from fuel is used to move the car down or run accessories, such as air conditioning. The remaining energy is lost to engine and driveline inefficiencies and idling, according to the US DOE. Automobile efficiency can be improved through changes to the engine and the transmission.
Several engine technology improvements can affect efficiency, such as direct fuel injection systems that create more precise timing and control of fuel mist, which creates higher performance and lower fuel consumption. Turbochargers and superchargers may allow more compressed air and fuel to be injected into the engine cylinders, generating extra power from each explosion, which allows manufacturers to user smaller engines without sacrificing performance. An integrated starter/generator also can automatically turn the engine off when the vehicle comes to a stop and restart it inst when the accelerator is pressed so that fuel isn’t wasted during idling.
Regenerative braking can be used to convert mechanical energy lost in braking into electricity, which is stored in a battery and used to electrify the starter.
In addition improvements to the transmission can lead to better fuel economy. For example, what is known as ‘continuously variable transmission (CVT)’saves fuel by using a pair of variable-diameter pulleys connected by a belt or chain that can produce an infinite number of engine/wheel speed ratios. This replaces traditional gears. Another transmission improvement is automated manual transmission (AMT), which combines the most efficient features of manual and automatic transmissions.
Computer chips also have enhanced automotive efficiency by allowing engines to create more power and fewer emissions with less energy. Vehicle manufacturers also can improve fuel economy by replacing steel with lighter weight aluminum, magnesium, and plastics or composites. In the years leading up to 2007, the amount of steel in a light vehicle decreased from 41.4% to 40.3% and advanced materials increased by 0.4%, according to NREL
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