Dense Energy is Green

Do you like it when Mother Nature can roam unperturbed by human cultivation? If so, you must like high energy density. 

There is this tendency for many of us to think that what nature provides is free - the wind blowing, the sun shining, the awesome energy in waves.  But these power sources are incredibly diluted and require massive areas of human cultivation to capture any meaningful amounts of energy. 

Several studies about power density have been released over the years, most notably by Vaclav Smil.  In the graph below, we take power density data of various publications by Smil, Ridley, Van Zalk & Behrens, and Noland et al., together with averages for each primary energy category. 

There are order-of-magnitude differences in power densities. That’s why this is plotted on a logarithmic scale, where it is easy to see 1,000x differences in a single graph.  I have sorted primary power sources by power density, from about 0.1 W/m2 for crops all the way up to more than 1,000 W/m2 for nuclear power.  The ultimate green power.

If I am willing to ignore the intermittency issues - the differences in land use are ENORMOUS.  Compared to energy produced by an oil & gas operation, solar requires 80x more land while corn ethanol requires a whopping 4,000x more land to produce the same amount of energy. 

Dense energy keeps more of the rest of the planet green

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