Improving the energy efficiency of appliances and equipment can result in reduced energy consumption in the range of 10 to 70%, with the most typical savings in the 30% to 40% range (Acosta Moreno et al., 1996; Turiel et al., 1997). Implementation of advanced technologies in refrigerator/freezers, clothes washers, clothes dryers, electric water heaters, and residential lighting in the US is estimated to save 3.35EJ/yr by 2010, reducing energy use of these appliances by nearly 50% from the base case (Turiel et al., 1997).
A number of residential appliances and electronic devices, such as televisions, audio equipment, telephone answering machines, refrigerators, dishwashers, and ranges consume electricity while in a standby or off mode (Meier et al., 1992; Herring, 1996; Meier and Huber, 1997; Molinder, 1997; Sanchez, 1997). These standby power losses are estimated to consume 12% of Japanese residential electricity, 5% of US residential electricity, and slightly less in European countries (Nakagami et al., 1997; Meier et al., 1998). Metering studies have shown that such standby losses can be reduced to one watt in most of these mass-produced goods (Meier et al., 1998). The costs of key low-loss technologies, such as more efficient switch-mode power supplies and smarter batteries, are low (Nadel et al., 1998) and a recent study found that if all US appliances were replaced by units meeting the 1-watt target, aggregate standby losses would fall at least 70%, saving the USA over US$2 billion annually (Meier et al., 1998).
Photovoltaic systems are being increasingly used in rural off-grid locations, especially in developing countries, to provide electricity to areas not yet connected to the power infrastructure or to offset fossil fuel generated electricity. These systems are most commonly used to provide electricity for lighting, but are also used for water pumping, refrigeration, evaporative cooling, ventilation fans, air conditioning, and powering various electronic devices. In 1995, more than 200,000 homes worldwide depended on photovoltaic systems for all of their electricity needs (US DOE, 1999a). Between 1986 and 1998, global PV sales grew from 37MW to 150MW (US DOE, 1999b). Rural electrification programmes have been established in many developing countries. In Brazil, more than 1000 small stand-alone systems that provide power for lighting, TVs, and radios were recently installed in homes and schools, while two hybrid (PV-wind-battery) power systems were installed in the Amazon Basin to reduce the use of diesel generators that supply power to more than 300 villages in that area (Taylor, 1997). Similar projects have been initiated in South Africa (Arent, 1998), Egypt (Taylor and Abulfotuh, 1997), India (Stone and Ullal, 1997; US DOE, 1999b), Mexico (Secretaria de Energia, 1997), China, Indonesia, Nepal, Sri Lanka, Vietnam, Uganda, Solomon Islands, and Tanzania (Williams, 1996). Recent developments promoting increased adoption of photovoltaic systems include the South African Solar Rural Electrification Project (Shell International, 1999), the US Million Solar Roofs Initiative (US DOE, 1999a), the effort to install 5000MW on residences in Japan by 2010 (Advisory Committee for Energy, 1998), and net metering, which allows the electric meters of customers with renewable energy generating facilities to be reversed when the generators are producing energy in excess of residential requirements (US DOE, 1999b).
Distributed power generation relies on small power generation or storage systems located near or at the building site. Several small scale (below 500kW), dispersed power-generating technologies are advancing quite rapidly. These technologies include both renewable and fossil fuel powered alternatives, such as photovoltaics and microturbines. Moving power generation closer to electrical end-uses results in reduced system electrical losses, the potential for combined heat and power applications (especially for building cooling), and opportunities to better co-ordinate generation and end-use, which can together more than compensate for the lower conversion efficiency and result in overall energy systems that are both less expensive and emit less carbon dioxide than the familiar central power generating station. The likelihood of customer sites becoming net generators will be determined by the configuration of the building and/or site, the opportunities for on-site use of cogenerated heat, the availability and relative cost of fuels, and utility interconnection, environmental, building code, and other regulatory restrictions (NRECA, 2000).
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