ABSTRACT
From the great oceans and swamps of prehistoric time came the most popular energy sources of our time. Plants and animals store solar energy from the sun, and retain some of that energy when they die. Accumulations of biomass were entombed by layers of mud and silt for hundreds of millions of years, where pressure and heat transformed them into the simpler chains of carbon and hydrogen that make up the fossil fuels we burn today. These resources provide a different type of challenge than deciding when to harvest a tree. With oil, it is no longer a question of whether to wait for the next incremental growth in the resource-any realistic discount rate makes the present value of supplies that may be created in thousands or million of years virtually zero.
