You can flip off your widescreen TV with the remote control. Power down your computer to standby. Unplug your cellphone from its charger. But as you leave the room, the "wall warts" -- those small boxes plugged into the wall sockets that power your electronics -- stare with glowing diode eyes in accusation: You are still using power.

In homes and offices everywhere, the power drained by idle electronics adds up to what Andy Williams says is a substantial waste.

Williams is vice president of a company called On Semiconductor. Using more efficient components and design, his company and others make devices that sharply cut the energy appetite of the "wall warts," both on standby and in use. He sees this as a key path to the future that will cut energy use and help curb global warming by ingenious use of technology.

"We're talking about the exact same principle as replacing incandescent light bulbs with compact fluorescent ones," he said from Phoenix. "If our products were built into all consumer electronics -- computers, flat-screen TVs, cellphones -- we could save 800 million pounds of carbon emissions."

His is a vision that dances enticingly in contrast to the doomsday predictions of runaway global warming and the oppressive remedies to fix it. Believers say technology will save us, creating a cleaner, cheaper, less-polluting society that will not require such burdensome changes in how we live.

"I believe with technology pretty much available today or in the very near short term, if we could move those fully into the market, we could get a 30 to 40 percent reduction in greenhouse gases," said Dana Christensen, associate director of engineering sciences at the Oak Ridge National Laboratory in Tennessee, a government-supported research center that studies this question, among others.

The caveat is crucial: if the technology is put to use. That is not as easy as it sounds. And no matter how enthusiastically better technology is adopted, it wouldn't fix the whole problem by itself. But it could go a long way toward the solution, experts say.

Striving for Efficiency

Technological societies are constantly striving to create ways of doing things more efficiently. Advances in efficiency in the past 30 years have led carbon emissions to grow only half as fast as the world's economy, according to Robert Socolow, a Princeton University engineer. But those savings have been offset by the rise in population and consumption.

Still, the potential for energy savings through bright ideas, clever engineering and new inventions is impressive. In Toronto, for example, last year's "Green Living Show" prominently displayed products already on the market to save energy. One company makes old tires into impermeable and energy-efficient roofs for homes. Another demonstrates an invention that duplicates a pen's movements over the Internet -- signing papers remotely without a trip.

On a broader scale, the mundane trappings of our modern life are becoming more efficient. Household appliances, including the thirstiest of them, furnaces and air-conditioners, have steadily diminished their energy consumption in the past three decades. Today's new kitchen refrigerators, for example, use 70 percent less power than those made in the 1970s.

More than one-third of all energy used in the United States goes to heat, cool and power buildings. A little more than half of that is for homes; the rest, for commercial buildings. All can be made to use less power.

Buildings can be made with efficient materials such as old-fashioned straw covered with stucco or new-fashioned polystyrene boards, instead of plywood; with insulation that doubles the energy-savings rating properties; with heat-exchange systems and fewer leaks; with windows that reject heat and admit light; and with designs that make the most of the sun's energy.

In transportation, the technologies to produce more efficient cars have been on the drawing board for years -- and in the case of GM's withdrawn "EV1" car of a decade ago, briefly in production. Foreign automakers have long offered lighter, smaller, more efficient cars, and, pushed by $3-a-gallon gas and by states such as California, U.S. automakers are finally unlocking technology to increase fuel efficiency.

"I don't think there's any doubt we have the existing technologies to double fuel efficiency in vehicles," said Robert Schock, a consultant to the Lawrence Livermore National Laboratory who is also director of studies at the World Energy Council of London, and a lead author of the energy report by the Intergovernmental Panel on Climate Change. "We could significantly reduce the amount of carbon dioxide that goes into the transport sector, which is about 30 percent of the total.

"In buildings here in California, I couldn't get a permit for a remodeled room without screwing in the compact fluorescent light bulbs. And industries already understand the profit motive of doing things more efficiently," Schock said. "With energy efficiency alone, we could cut carbon dioxide emissions at a reasonable cost by probably one-third."

The Problem of Replacement Cost

If the technology exists, what, then, is the problem? The cost of replacing anything, from a power plant to a coffee maker, is the first hurdle. Even if the logic of long-term savings makes it an economical move, individuals and companies often have no money for the initial replacement cost.

In construction, for example, when a builder is trying to make a product that can sell for a lower price and a higher profit, he or she has little incentive to use expensive, energy-efficient techniques and materials.

Even if all new buildings were constructed efficiently, it would take 50 to 75 years or more to substantially replace the existing stock. Unless owners are encouraged -- or required -- to retrofit their buildings with energy-saving materials, the gains from existing and future technology advances will be slow.

In transportation, U.S. automakers have long resisted moves to increase fuel efficiency. Appliance makers argue that cheaper, less efficient, products should be offered as well as more expensive, efficient ones. In industry, tradition, inertia and capital costs slow the adaptation of efficient technologies. Vested interests in old technologies fight to preserve their business. New technologies can be risky and failure disastrous.

Some argue that this is where government should come in. Federal, state and local governments can set standards for more efficient buildings, for example, or more efficient cars or appliances. Lawmakers can require industries to curb greenhouse gas pollution. Subsidies, taxes, incentives and fees can be structured by governments to change the economic equations: to charge big energy users more money per kilowatt rather than less, for example, or to end tax breaks for fossil fuel exploration in favor of subsidies for alternative energy development.

Daniel Sosland, director of the nonprofit group Environment Northeast, did a detailed study in December 2006 of how the northeastern United States and eastern Canada could cut greenhouse emissions. Of the group's five top recommendations, the first three were to improve energy efficiency with what we know how to do already.

"We have built our buildings and roads and transportation around cheap energy. The buildings, appliances have been fairly inefficient," Sosland said. "It's far cheaper to make them efficient" than to do anything else.

"It wouldn't solve the problem," he said. "But it's the cheapest first step. And you have to do it to be on the right path."