Count me as a skeptic...

...when it comes to the Zero Carbon Australia plan that says Australia could be powered by renewable energy by 2020:

Our research was undertaken with two explicit parameters: energy technologies selected had to be both commercially available and from carbon-free renewable energy sources. This explains why the ZCA Plan identifies a 60/40 mix of concentrated solar thermal (CST) power and large-scale wind developments as the backbone of a decarbonised energy system. Together with existing hydropower, investment in CST with molten salt storage, backup from a small percentage of biomass power, an upgraded electricity grid, and comprehensive energy efficiency measures, Australia can reliably meet its energy needs from renewable electricity generation. The technologies selected were not preordained; rather they were chosen on the basis that they worked within ZCA’s parameters.

The ZCA scenario also includes natural gas. Under the plan, Australia would use existing gas infrastructure in a staged scale-back, until the last gas power plants are mothballed in 2020. The most carbon-intensive coal power plants must be first to be decommissioned as large-scale renewables come online, made possible by the deployment of CST power towers with molten salt storage for 24-h operation.

Brave New Climate has been critical of this plan before. Here's one post about it, but there are others.