When I think about it... alot (not all of course) of our typical energy sources can be traced back to the Sun.
Robot Battery is powered from the wall
The wall is powered from the power plant
The power plant runs on Coal, Oil, Natural Gas, Wind power, Solar Power, Hydroelectric, etc... (I left out nuclear, tidal and geothermal on purpose) All of which can be traced back to the Sun.
Coal-Organic-Plant material-Sun to grow the plant/animal
Oil-Organic-plant material-sun to grow the plant/animal
Natural gas-organic-plant material-sun to grow the plant/animal
Wind-solar energy moving the air
Solar-It's the sun, dude
Hydroelectric-Evaporation and precipitation raising water's potential energy
Here's one to think about. Full Cells - where are we going to get the Hydrogen? It doesn't just come when we call it. (Or does it? Hydro... Hyddie... are you there?)
