Land is the  great net by which we capture current solar income, which (eventually, I believe) we will have to learn to live within.  

`The earth receives more energy from the sun in just one hour than the world uses in a whole year'. So, does that mean that we can convert to solar and everything is going to be fine?

No: I show that the current rate of power consumption of the `developed' world is unsustainable. The `developed' world must cut its consumption by at least a factor of 10, and must put all possible resources into developing solar energy technology, which, along with hydroelectricity, is the only^* significant source of sustainable power.

^{* - Some conditions may apply! See below for details}