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.A BUSINESS MAY HAVE high gross receipts and still go broke; it is the net, the profit after costs are subtracted, that determines viability.For any potential energy resource, the fundamentals are the same.Tips on how to book cheap India Flights Sign Up for the Cheap Oair Newsletter Get exclusive deals on cheap flights to India sent right to your inbox!The Cheap Oair newsletter delivers you the best travel deals, news and tips to help you plan trips to top destinations around the world for less.How much energy is available after subtracting the energy costs to extract, process, and deliver the resource?
With coal-derived electricity, the calculation would include the life cycle from mine to power plant to electric grid.
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?
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.
For fossil energy generally, the trend is downward despite technological advances in exploration and drilling. Some studies suggest that corn-derived ethanol actually has a negative net energy ratio—that is, more energy than a gallon of ethanol can deliver is used to produce a gallon of ethanol.