Myths/there are no sustainable energy sources/cost
The "cost" argument against sustainable energy insists that sustainable energy costs more than fossil-fuel energy.
- "The total cost per unit of electricity produced, without significant government subsidies, is usually substantially less [for conventional, dirty power] than the production and installation costs of the solar voltaic panels [to produce the same amount of energy] over the lifetime of the panels."
This claim is simply wrong; investment in a solar cell system generally pays back in reduced costs after a period of several years; after that, the energy is effectively free for the remaining life of the hardware, which is generally two or three decades. 
This also ignores the long-term environmental costs of using fossil fuels, which are (of course) "externalized" and not figured into the retail price.
Costs are also continuing to drop dramatically due to the accelerating pace of research.
- The Solar Cell That Turns 1 Photon into 2 Electrons: the first commenter makes the claim that "the total cost per unit of electricity produced, without significant government subsidies, is usually substantially less than the production and installation costs of the solar voltaic panels." In the next comment, he corrects this: "Oops! I meant of course that the total cost per unit of electricity produced is substantially more than that from conventional, dirty power, over the lifetime of the PVP."
- Lifecycle Costs of Photovoltaics "The estimated energy payback time (EPBT) for PV ranges from 6 years to 1.1 years, depending upon the type of PV, the insolation, and the installation. PV panels are usually rated to have a lifetime of 25 to 30 years."
- As Solar PV Efficiency Climbs, Costs Likely To Drop: a report on recent developments in solar cell technology