The Sun Fuels Life

The News-Leader printed Photosynthesis Key to Life in its education page.  This feature intended for young students has a lot of lessons for all of us.  Virtually all life except those in the deepest ocean vents derives its energy from photosynthesis.  Even these require the sun to prevent the oceans from freezing.
Many ancient peoples worshiped a Sun God.  While their theology is quite debatable, they were on to something long before the study of biology developed.  Our world is a closed system.  All of our resources are currently enclosed within our planet. The only energy which comes from outside the planet earth is the sun.
The sun's rays are the key ingredient in photosynthesis.  Without its constant bombardment of energy, the planet would freeze leaving no rain or available water.  Wind energy depends on changes in air temperature created by the sun.
All of our current economic system is based on growth and competitive pricing of resources.  If there is a shortage of anything, the price goes up, creating the incentive to produce more.  Provide excess production and the price goes down.
This works well as long as the resources are available.  Unfortunately, there is no more water on the planet now than was present before the dinosaurs.  Oil and natural gas are only produced slowly over millions of years by the death and prolonged burial of carbon based plants and animals. 
In recent decades we have started to seriously strain the world's bank account of energy and water.  Herman E. Daly explains the problem in his short article, Economics in a Full World.  He gives a simple explanation of the situation we face "in a world where the economic mantra is growth without consideration of the inability to expand beyond our planet for additional resources."

Relying on growth in this way might be fine if the global economy existed in a void, but it does not.  Rather the economy is a subsystem of the finite biosphere that supports it. When the economy's expansion encroaches too much on its surrounding ecosystem, we will begin to sacrifice natural capital (such as fish, minerals and fossil fuels) that is worth more than the man-made capital (such as roads, factories and appliances) added by the growth.  We will then have what I call uneconomic growth, producing "bads" faster than goods--making us poorer, not richer.

Once we pass the optimal scale, growth becomes stupid in the short run and impossible to maintain in the long run. Evidence suggests that the U.S. may already have entered the uneconomic growth phase. Scientific American-2005

I would recommend that you download and read the PDF file Economics in a Full World.  For a more complete but clear understanding of economics past and future, Daly's 1997 book, Beyond Growth: The Economics of Sustainable Development is a good resource.