With more than 1.5 billion people online around the round, scientists estimate the carbon footprint of the internet is growing by more than 10 per cent each year.
Many internet companies are struggling to manage the costs as energy bills soar, while their advertising revenues come under pressure from the recession.
It is thought one site facing problems is video website YouTube. Although now the world's third-biggest website, it requires a heavy subsidy from Google, its owner.
Recent analysis by Credit Suisse suggest it could lose as much as £317m this year.
As the demand for electricity grows, the computer industry's carbon footprint is also increasing, although tracking the growth of its energy use is difficult, as internal company estimates of power consumption are rarely made public.
A study by Rich Brown, an energy analyst at the Lawrence Berkeley National Lab in California, commissioned by the US environmental protection agency, suggested US data centers used 61bn kW of power in 2006 - enough to supply the UK for two months.
"Efficiency is being more than overwhelmed by continued growth and demand for new services," he said. "It's a common story... technical improvements are often taken back by increased demand."
Urs Hölzle, Google's vice-president of operations, said it was struggling to contain energy costs despite developing its own data centers.
"You have exponential growth in demand from users, and many of these services are free so you don't have exponential growth of revenue to go with it," he told The Guardian
"With good engineering we're trying to make those two even out … but the power bill is going up."
Mr Hölzle dismissed concerns about the environmental impact of using the internet as "overblown".
"One mile of driving completely dwarfs the cost of a search," he said. "Internet usage is part of our consumption, just like TV is, or driving."
To avoid future scenarios such as possible website failures and power cuts, the industry is attempting to combat the problem - introducing new designs for data centres, innovative cooling methods and more investment in renewable energy.
Researchers at Microsoft's £50m research lab in Cambridge are replacing energy-consuming new machines with the systems used in older, less powerful laptops.
Andrew Herbert, the director of Microsoft Research Cambridge, said: "We found we can build more energy-efficient data centers with those than with the kind of high performance processors you find in a typical server."
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