A number of research teams have tackled the whole “how much could (or should) renewable energy power our grid?” question. Of course, the regions studied, goals of the studies, technology assumptions, and other parameters have varied, so the studies come to various conclusions. Here are some of the most notable studies I’ve seen:

• Here’s How To Build 100% Clean Renewable Energy In The US Before 2040
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  Getting To 100% Renewable Energy In the US
• The Solutions Project: How 139 Countries Can Hit 100% Renewable Energy
• Wind, Solar, & Storage Could Power Full Electric Grid Cost Effectively 99.9% Of The Time By 2030: Report
• Clean Energy Could Supply U.S. with 70% of Electricity by 2030, NOAA Director Says
• Renewable Energy Can Power the World 100% (Reminder)
• How To Get Europe To 100% Renewable Energy [Full Report]
• 95% Renewable Energy World Possible by 2050 with NO Technology Breakthroughs
• Scenario Study for the World,  “Renewable Energy Outlook 2030”
• 80% Clean, Renewable Energy by 2050: More Than Possible, But Need More Political Will (& Public Demand)
• The Offshore Valuation (UK)
• 100% Renewable Energy For Australia Not So Costly
• Iceland Already Gets Its Electricity 100% From Renewable Energy
• Tokelau Has Hit 100% Renewable Energy
• Denmark Saw 40.7% Of Electricity Produced From Renewable Energy In 2011, 28.1% From Wind Energy (and Denmark Is Aiming For 50% Electricity From Wind By 2020)
• Germany Had 26% Of Its Electricity Come From Renewable Energy In The 1st Half Of 2012
• Germany Went On To Install A Record Amount Of Solar Power In 2012, A Whopping 7.6 GW Of New Capacity
• Scotland Is Aiming For 100% Renewable Power Supply By 2020 (Up From An Earlier Target Of 100% Renewable Power By 2025)
• 94% Renewable Electricity By 2017 Is The Goal For Nicaragua
• 90% Renewable Electricity By 2015 Is The Goal For Uruguay
• And Here’s A List of Countries With Over 60% Renewable Electricity Today
• A Fundamental Look at Energy Reserves for the Planet (source of image above)
• Renewable energy sources: Their global potential for the first-half of the 21st century at a global level: An integrated approach
• Role and Potential of Renewable Energy and Energy Efficiency for Global Energy Supply
• Global Energy Assessment
• On the Global & Regional Potential of Renewable Energy Sources
• Potentials and prospects for renewable energies at global scale
• Renewable Energy Technical Potential
• UN IPCC: renewable energy potential is higher than energy demand

Article from cleantechnica.com