One of the most consistent arguments directed at renewable energy in general is that it can't provide enough energy to power whole societies or the planet on its own merits; it will always require back up, or base load power from sources such as nuclear or fossil fuels.
This claim is repeated across many forms of media by laypeople and energy 'experts'. A number of reports now exist, to counter this claim. These scenarios range from environmental groups such as Greenpeace to accountancy and service firms such as Pricewaterhousecoopers. They include 100% renewable energy scenarios as well as low carbon mixes and limited nuclear.
Pricewaterhousecoopers have a 2010 report titled 100% Renewable Electricity: A Roadmap for Europe and North Africa.
The report can be downloaded here and "examines the potential for powering Europe and North Africa with renewable electricity exclusively by 2050 and the opportunities this transformation to the power sector presents. The study provides policy makers and business leaders with clear direction and a step wise approach on how to achieve the 2050 vision.
Greenpeace released a report in conjunction with the Institute of Technical Thermodynamics at the German Aerospace Centre.
The 2010 report, Energy Revolution: A Sustainable World Energy Outlook "provides a detailed practical blueprint for cutting carbon emissions while achieving economic growth by replacing fossil fuels with renewable energy and energy efficiency. This phase-out of fossil fuels offers substantial benefits such as energy security, independence from world market fuel prices as well as the creation of millions of new green jobs. It can be downloaded here. An iphone application summarising the report can also be downloaded from the same page.
World Wildlife Fund
The World Wildlife Fund has also produced a report in conjunction with ECOfys. It "demonstrates that by 2050, power, transport, industrial and domestic energy needs could be met overwhelmingly from renewable sources vastly reducing anxieties over energy security, pollution and not least, catastrophic climate change." The report can be downloaded here
Roadmap 2050: A Practical Guide to a Prosperous Low Carbon Future has been developed by a large corsortium of experts under the European Climate Foundation.
Completed in 2010, "The mission of Roadmap 2050 is to provide a practical, independent and objective analysis of pathways to achieve a low-carbon economy in Europe, in line with the energy security, environmental and economic goals of the European Union. The Roadmap 2050 project is an initiative of the European Climate Foundation (ECF) and has been developed by a consortium of experts funded by the ECF." Roadmap 2050 download page.