Summary: I (NJ Hagens) heat our home (definitely not shown above) with wood. The trees nearest my house are small but in the cold of winter if I’m out of firewood, those are the ones I’ll go cut and bring into the house. We have plenty of trees on our land, but there is a steep hill with no road across the gulley; the huge old growth white oaks and maples there have substantially more cubic feet of firewood, but will take substantially more effort – if even possible – to get the firewood to my house. In the above example, the purple circles represent easy to access firewood, irrespective of quality. The yellow circle represents firewood that is possibly accessible, and the red circles represent prime firewood, but with no roads or even ways a draft horse could haul the wood back to the house. There would be a substantial ‘energy cost’ to accessing the wood, even though the trees are clearly plentiful. Ergo, an accurate census of the forest shown in the picture for total trees/BTUS of heat potential would include the energy spent getting the energy .
This simple phenomenon plays out with oil and other resources as well. We think of the cost of oil in terms of dollars, but that is not the true cost. It requires about 245 kilojoules of energy to lift 5 kg of oil 5 km out of the ground. 141 Similar biophysical costs apply to every energy extraction/harnessing technology we have. These costs may be parsed into financial terms for convenience, but these physical input requirements will not vary, whether the number of digits in the world’s banking system increases, shrinks or goes away. The costs are taken from the fossil energy itself. Even the devices we build to supply “alternative” energy (meaning from the sun and wind) also incur fossil energy costs for their manufacture and need to be maintained and periodically replaced.
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