Can renewable energy make a dent in fossil fuels?
 

4.2 billion.

That's how many rooftops you'd have to cover with solar panels (http://www.news.com/8301-11128_3-9922124-54.html) to displace a cubic mile of oil (CMO), a measure of energy consumption, according to Ripudaman Malhotra, who oversees research on fossil fuels at SRI International. The electricity captured in those hypothetical solar panels in a year (2.1 megawatts each) would roughly equal the energy in a CMO. The world consumes a little over 1 CMO of oil a year right now and about 3 CMOs of energy from all sources.
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*Source: Green Tech Blog (News.com) (http://www.news.com/8301-11128_3-9928068-54.html)*

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