Though we tend not to mention it in the same breath as transportation, heating our homes, or lighting our offices, downloading data consumes energy too. As more people turn to the internet for increasingly data-intensive activities, computer scientists from the U.K.’s Bristol University decided to crunch the numbers and project the ultimate impact on the environment. The results are staggering.

The researchers assumed that people in the developed world would maintain the same level of media consumption, but move it entirely to the cloud, and that the global middle glass would reach a similar level of data use. With those assumption in place, the researchers reckon that each person will demand, on average, over 3 gigabytes of data per day. That’ll come to 2,570 exabytes per year for the global population, by 2030. (An exabyte is a billion gigabytes.) The average power needed to sustain such activity would be 1,175 gigawatts. It takes an entire large coal-fired power plant to produce just one gigawatt of energy, so imagine 1,175 of those churning out power just to fuel the world’s data hunger.

Big numbers–as any global figures are–and they’ve led researchers Chris Preist and Paul Shabajee, who present their findings today at the IEEE CloudCom 2010, to propose innovative strategies for containing consumption. Intriguingly, Preist and Shabajee talk about cloud computing in terms more familiar to recycling programs: they want us to change our behavior to reduce “digital waste.” Taking a page from behavioral economics and the authors of the popular book Nudge, they advocate “persuasive” web design that nudges users into choosing less data-intensive options–avoiding that high-res photo when a medium-res would suffice.

“One of the main messages of my paper is that the main solution for this

is to continue to make servers more powerful and more efficient,” Preist tells Fast Company, adding that it’s important for those in “green IT” to continue making efficiency improvements. “The impressive efficiency gains that have been achieved so far have been

overshadowed by increased demand for broadband services.”

Most reports that look into the future of any sort of consumption have apocalyptic overtones. But Preist, in the end, is relatively optimistic. As he said recently in a release: “This research suggests that in a future which is increasingly environmentally constrained, there is still a good chance that broadband connectivity can be provided equitably to the majority of the world.” Not so of other realms, he points out: “This contrasts significantly with other aspects of western lifestyle, such as aviation, which could become increasingly the preserve of the wealthy.”

The usual caveats of scientific research apply: namely, more is needed. Though the academics tried to take all the variables into account–foreseeing an era when high-def online video is the norm, for instance–further investigation is needed into the role that mobile devices play in network energy use, and in the emissions caused by manufacturing the technology that enables us to access the Web in the first place.