How many radioactive bananas would you need to power a house?
Energy densities of various substances and&#x2F;or reactions is pretty fascinating concept.<p>Some of the most interesting energy analysis I&#x27;ve come across (Vaclav Smil and David MacKay especially) describe energy in terms of <i>area</i>:  what are the comparable <i>land areas</i> which would have to be dedicated to specific sources or forms of energy or fuels, and how do those compare?  One of Smil&#x27;s descriptions of petroleum wells is &quot;punctiform&quot;, which I love.  A hole in the ground, only about 20 cm in diameter, can provide years to millennia of human energy output, per day.<p>1 litre of oil is equivalent to about 3 days of human energy output (at 3,000 kilocalories&#x2F;day).<p>1 gallon of oil is eqivalent to about 11 days of human energy.<p>One of the oldest oil wells in production (the First Oil Well of Bahrain) produced 80,000 barrels of oil per day initially.  That&#x27;s over 1,000 years of human energy equivalent.<p>By comparison, the yeild of current biomass production is far, far less.  The difference, of course, is that oil <i>is</i> biomass, accumulated, converted, and concentrated over hundreds of millions of years.  We&#x27;re consuming it at &gt; 5 million times its rate of formation.  (See Jeffrey S. Dukes, &quot;Burning Buried Sunshine&quot; (2003).)<p>In terms of radioactivity, the net metabolic rate of the Sun&#x27;s core is <i>lower</i> than that of a human, measured in energy&#x2F;mass.  Solar metabolism is closer to that of reptiles, about 1&#x2F;5 of mamallian metabolic rates.<p>Chemical energy is less productive than the <i>most effective</i> nuclear transitions, but its shear abundance and ease of utilisation tends to weigh in its favour.