Put another way, more than half (i.e. 56.2%) of the energy that flows through our economy is ultimately wasted.
The predominance of inefficiency is conveyed by the energy-flow diagram below: it shows the country’s energy fuel inputs (e.g. coal, natural gas) on the left side, and end-use energy consumption (e.g. residential energy usage, transportation energy usage) on the right side.
Of the 97.3 quadrillion British Thermal Units (known as “quads”) of raw energy inputs that flowed into the US economy in 2011, only 41.7 quads were constructively used at the end of the day (as “energy services”). The other 55.6 quads were, in essence, wasted. This waste, summarized in the top right of the diagram, is euphemistically classified as “rejected energy.”
Most of the economy’s energy waste stems from the electricity production sector (because most power plants are relatively inefficient) and the transportation sector (internal-combustion vehicles are relatively inefficient, but they are getting better).
Other interesting insights that can be gleaned from the 2011 diagram:
- Coal, natural gas, and petroleum collectively accounted for 82.1% of US primary energy consumption
- Solar, geothermal, and wind collectively accounted for 1.6% of US primary energy consumption
- The most sizable category of energy utilization in 2011 was electricity generation (39.2 quads)
The Lawrence Livermore National Laboratory report notes that, overall, the US used slightly less energy in 2011 than in 2010 (97.3 quads compared to 98 quads), mainly due to “a shift to higher-efficiency energy technologies in the transportation and residential sectors.”
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