If left to their own devices, many equipment designers would opt to either build or buy highly efficient power supplies for their applications. More efficient supplies are often smaller, lighter and cooler running than their less-efficient counterparts. Thus, there's strong motivation to use them, particularly in consumer applications. But in these same applications, the desire for power efficiency is routinely trumped by the demand for low cost. Although technology advances help offset cost considerations, what's really needed is greater demand in the marketplace for more efficient products.
The U.S. Environmental Protection Agency (EPA) is seeking to spur that demand, as evidenced by its announcements at February's Applied Power Electronics Conference (APEC). The EPA, along with the California Energy Commission, is sponsoring an international design competition for energy-efficient power supplies. Entrants in the competition will fall into one of two categories. The first is for market-ready designs — both embedded and external power supplies — that reduce energy consumption in specific types of consumer goods.
In the second category, cost consideration is removed so entrants from industry and academia can demonstrate the highest levels of efficiency that technology and clever design allow. This contest will run throughout the year, with winners announced at next year's APEC. For contest details, visit www.efficientpowersupplies.org.
This competition is just one aspect of the EPA's broader strategy: The agency aims to transform the North American marketplace by raising the average efficiency of typical power supplies, while boosting demand for more efficient supplies. To do this, the EPA will expand its Energy Star program, which has traditionally focused on end-use products, to create market incentives for both power-supply manufacturers and their customers.
Components of this strategy include selecting a standardized method for measuring the efficiency of external power supplies; identifying the types of supplies that will be addressed; establishing performance criteria for external power supplies; and incorporating an external power supply specification into Energy Star specifications.
To increase their effectiveness, the agency will try to coordinate its efforts with that of foreign agencies also attempting to implement voluntary initiatives. Given the amount of power-supply activity in China, it's no surprise the EPA has begun to collaborate with the China Certification Center for Energy Conservation Products (CECP).
The EPA has taken its first step by developing a standardized test procedure for single-voltage, external ac-dc power supplies. It also has developed a draft Energy Star specification for these supplies. The test procedure is available online at the site listed previously, while the draft specification is available at www.energystar.gov/power supplies. Although these efforts begin by focusing on external supplies, the agency also plans to develop specifications for internal (embedded) power supplies.
The proposed Energy Star specification deals with power-supply efficiency in both active and standby operation. In doing so, it builds on existing initiatives worldwide to reduce standby power consumption for various products. That's a logical step, given that active mode operation accounts for nearly 75% of power-supply energy use, according to the EPA. Couple that fact with the disparity between the low efficiencies of existing supplies (often 30% to 60%), and the potential for 90% efficiency in better designs. The EPA estimates a potential savings of 32 billion kWh/year.
This type of data provides valuable perspective for both engineers and consumers. Although most consumers are unlikely to become familiar with the EPA's statistics on power-supply efficiency, they will — through the Energy Star program — become more aware of the role of power electronics in their daily lives.
In addition to making a positive impact on our environment, this heightened awareness may enhance the prestige of power-supply design and attract new minds to the field. Such developments could help to sustain the vitality of the power-supply industry and promote continued innovation.