Geneva - Dramatically expanding broadband access would boost the global economy and could do more good than investing in HIV prevention or clean drinking water, according to a study published on Thursday.Economists commissioned by think-tank Copenhagen Consensus Centre calculated that tripling access to mobile broadband networks in developing countries by 2030 would boost economic growth by $22 trillion."There's a well-established increase in GDP growth if you have more broadband, and it doesn't take very much of a higher growth rate to make a huge difference in people's lives," the head of the think-tank Bjorn Lomborg told AFP.Estimating that it will cost about $1.3 trillion to go from 21% coverage today to 60% coverage by 2030, bringing some three billion more people online, the study found the investment could rake in $17 worth of benefit for every dollar spent. Tripling fixed broadband coverage worldwide from 10% to 30%, or in the developing world from six to 20% during the same timeframe, would meanwhile reap $21 in benefits for each dollar spent, the study found.The study is part of a broader project in which a network of more than 100 economists are analysing the costs and benefits of a range of proposed global targets under discussion.Surprisingly, the analysis showed that from a purely economic perspective, hiking access to broadband was "phenomenally better than a lot of other proposals," Lomborg said.Some of the most obvious targets do fare better, with every dollar spent alleviating childhood malnutrition for instance expected to do $45 of good, according to earlier studies.But others do not stand up to the benefits of broadband expansion, with investments in clean water and sanitation seen bringing benefits of between $3-5 per dollar spent, Lomborg said. Investing in HIV treatment would meanwhile only do $2.50 of good for every dollar spent, while initiatives to preserve forests in protected land would cost more than the benefits created, he said. Calculating the benefits of proposed development initiatives based purely on economic gain can appear cold, Lomborg acknowledged.But with an almost eternal list of noble causes, he insisted on the importance of knowing the cost and benefits of projects when trying to choose which to invest in first.Just because an initiative doesn't top the list of dollars gained does not mean it shouldn't be invested in for other reasons, he said.