However, Patricia and Tim have never had sex before today. Patricia had dated the same boy all through high school and then married him just a few years later. Just about a year after the wedding, Tim hadn't seen Patricia in weeks.
All their friends thought Patricia and her husband were crazy to get married so young, and Patricia's girlfriends told her that she should explore a little with other guys before committing to just one for the rest of her life. In fact, Tim never saw Patricia unless she was with her husband, which made it all the more surprising when she called him and asked him to come meet her, alone.
Declining oil field productivity has brought the average net energy ratio for conventional oil down to approximately 20:1 globally, with more remote or hard-to-refine oil significantly worse.
Renewable energy sources, excluding hydropower, are generally more diffuse and have lower net energy ratios than fossil fuels.
If high net energy sources are in decline, and no reasonable replacements are available, the result may be a painful restructuring as society rearranges economic activity to fit a diminishing energy supply.
For example, when tallying the energy required to build a solar photovoltaic panel, what should be included in the accounting?
The energy needed to mine the bauxite for the aluminum frame?
Oil, natural gas, and coal have provided a huge, high-quality energy subsidy to the modern world.