Renewable Energy's Hidden Cost

Scientific American magazine, sister publication of Nature, is no right-wing rag by anyone's estimation. If challenged to classify its political bent, I would place it squarely in the Libertarian camp, that is, socially liberal and fiscally conservative. When its article authors are not taking gratuitous pot shots at religious people, they are extremely honest in their assessments and conclusions on matters of science (which is where their focuses should remain, not on people's personal beliefs). Even when I do not agree with a particular viewpoint, the integrity is appreciated.

Always reliable for incredibly informative graphics and amazing artistry, the October 2013 edition of SciAm presented a chart depicting the total relative global greenhouse gas emission from metal production for various forms of energy conversion processes. The thumbnail image below uses circles whose areas (assumed, vs. relative diameters) indicate the quantity of each metal (denoted by color) required to produce one kilowatt-hour of energy. The monstrous yellow circle is silver content needed for solar energy (photovoltaic cells); it looks like a scale drawing of the sun and planets - perhaps no coincidence since it is for solar energy (I told you those SciAm folks are clever). The second largest circle also belongs to solar, and it is for tin. Molybdenum, copper, zinc, nickel, aluminum, and iron are the other metals needed by almost all sources. Believe it or not, there is at least a trace amount of uranium used by every process except hydro. As you might guess, the types of energy production systems that need the smallest amount of metals for processing are coal, gas, hydro, and oil. Nuclear owns the big blue uranium circle.

Keep in mind that the circles indicate not the quantity of each metal consumed per energy generation process type, but the greenhouse gas creation as a result of the mining, processing, and, I assume, end use. To be fair, the types with the big circles are relatively fledgling technologies and the learning curve is just beginning to steepen to where higher efficiencies will eventually be realized. However, at the same time advances are being made in the traditional energy sources that are making them more efficient and more environmentally friendly. Techniques for cleaner burning of coal and gas are constantly breaking new ground, as are the methods used for mining the raw materials. Fracking (hydraulic fracturing), for example, has recently seen great advances in terms of backfill material with reduced or totally eliminated toxicity. Coal scrubbing processes are following suit to minimize chemical holding areas and unintentional runoff.

Like it or not, mankind requires abundant and cheap access to energy to survive and thrive.

Posted  September 25, 2013