Last October, environmentally conscious Netheads everywhere got some excellent news. The pervasive use of broadband Internet connections and the tools and practices they enable could reduce greenhouse gas emissions by some 1 billion tons over the next decade, according to the American Consumer Institute. Widespread adoption of broadband in the United States alone would cut energy use by the equivalent of 11% of annual oil imports, the group says.

Clearly, though, when it comes to energy use, the Web is both a crusader and a culprit. Server farms and data centers burn mountains of CO₂, much of it to keep machines cool. But now a new crop of companies and thinkers is trying to make the Internet "carbon neutral" and find ways to use Web-based technologies to reduce worldwide energy consumption through "demand-response" schemes that give energy consumers more direct control over their energy use.

Internet-enabled capabilities like telecommuting, e-commerce, teleconferencing, and distance learning that have been around for decades are expected to play an increasing role in cutting energy consumption--reducing air travel and the need for warehouses, trips to the mall, and even malls themselves. The American Consumer Institute projects that telecommuting alone will cut CO₂ emissions by more than a half million tons over the next decade (see table, above). Overall, the Internet economy could help reduce growth in greenhouse gas output by 67% over the next several years, the study says, citing data from the Lawrence Berkeley National Lab.

"The future Internet represents an incredible business opportunity for researchers and corporations," says Bill St. Arnaud, senior director of advanced networks at Canarie, a nonprofit group focused on advanced Internet development in Canada. "It will allow them to deploy new economic models and create marketing opportunities where they will make profits by reducing CO₂ emissions."

St. Arnaud believes that Internet companies can slow global warming in two ways: by reducing the energy use of the routers and servers that make up the Internet's backbone, and by "bits-and-bandwidth for carbon" trading schemes that would provide incentives for individuals and companies to reduce their carbon footprints in return for free or reduced-rate broadband connections or downloadable music and films.

St. Arnaud isn't the only Internet luminary turning attention to how the Net and Web technologies can help the environment. Legendary Silicon Valley investors like John Doerr of Kleiner Perkins and Vinod Khosla, who made their fortunes from Internet-based technology, are now focused on slowing global warming, channeling billions of dollars into technologies such as solar power and wind farms. And Google has said it will build a series of renewable-energy plants that will produce a total of 1 gigawatt more cheaply than coal. That's enough to power a city the size of San Francisco, and the project is likely to cost a few billion dollars.

Couple the potential of Internet-related technologies with these investment engines and the optimists among us might foresee a significant dent in the energy crisis. But such pronouncements mask the inconvenient truth that the Internet hogs a great deal of power, particularly for big server farms on Google- and Amazon-like scales. Power consumption by data centers doubled between 2000 and 2005, according to Jonathan Koomey, a staff scientist at Lawrence Berkeley National Lab, and while the total amount of electricity used by the Web infrastructure is small--about 1.5% of all U.S. electricity consumption in 2006, according to the Environmental Protection Agency--it's one of the fastest-growing sectors. (It doesn't help that Google co-founder Larry Page released about 1.5 million tons of CO₂ flying 600 friends on private jets to his wedding on a Caribbean island.)

What's more, the Internet-related energy-reduction schemes that St. Arnaud and others envision, which involve disseminating information that will help people and companies reduce CO₂ emission growth, overlook the more direct and powerful ways that companies are using the Internet to actively reduce energy use.

Many of these more commonsensical plans revolve around the emerging demand-response industry, which matches electricity consumption to supply in real time. They use the Internet to do what it does best: enable IT managers and "chief carbon officers" to act on more accurate and timely data on energy consumption, prices, and supplies to control myriad devices over the network.

In other words, while Google snags headlines for equipping its Mountain View, Calif., campus with a huge solar array, the real work of using the Web to slow global climate change is going on in less celebrated locales, like the Boston offices of demand-response and energy-management provider EnerNOC.