Politicians have talked about “renewable” energy for so long that no one questions what it means any longer, writes Dawn Stover at Bulletin of the Atomic Scientists, a publication that prides itself on “inform[ing]  the public about threats to the survival and development of humanity from nuclear weapons, climate change, and emerging technologies in the life sciences.”  People think they know what energy sources are “renewable” — primarily the sun, the wind, and the water, although Stover includes biomass in the definition as well.  Stover points out that writers use quote marks around “clean” and “green” when discussing energy technology, but rarely around the word “renewable” — but argues that the concept of renewability deserves the same kind of skeptical treatment as “clean” or “green”:

As the US Energy Department explains it to kids: “Renewable energy comes from things that won’t run out — wind, water, sunlight, plants, and more. These are things we can reuse over and over again. … Non-renewable energy comes from things that will run out one day — oil, coal, natural gas, and uranium.”

Renewable energy sounds so much more natural and believable than a perpetual-motion machine, but there’s one big problem: Unless you’re planning to live without electricity and motorized transportation, you need more than just wind, water, sunlight, and plants for energy. You need raw materials, real estate, and other things that will run out one day. You need stuff that has to be mined, drilled, transported, and bulldozed — not simply harvested or farmed. You need non-renewable resources[.]

Solar is not renewable?  It is if all the energy you need is for a suntan, but not if you plan to convert it to electricity:

While sunlight is renewable — for at least another four billion years — photovoltaic panels are not. Nor is desert groundwater, used in steam turbines at some solar-thermal installations. Even after being redesigned to use air-cooled condensers that will reduce its water consumption by 90 percent, California’s Blythe Solar Power Project, which will be the world’s largest when it opens in 2013, will require an estimated 600 acre-feet of groundwater annually for washing mirrors, replenishing feedwater, and cooling auxiliary equipment.

What about wind power?  That requires an awful lot of steel, concrete, and less-ubiquitous items like rare-earth metals, such as neodymium and dysprosium that are hard to find and harder to extract — and that take a lot of energy to produce in usable form, as we’ll note in a moment.  That’s also true of solar panels.  How about dams and hydropower?  They make the steel and concrete needs of wind turbines look like a drop in the bucket.  That doesn’t take into account all of the electrical-transmission equipment needed to bring that power to market, and all of the real estate that takes. Stover describes what it would take to convert today’s energy demand into “renewable” energy production:

But meeting the world’s total energy demands in 2030 with renewable energy alone would take an estimated 3.8 million wind turbines (each with twice the capacity of today’s largest machines), 720,000 wave devices, 5,350 geothermal plants, 900 hydroelectric plants, 490,000 tidal turbines, 1.7 billion rooftop photovoltaic systems, 40,000 solar photovoltaic plants, and 49,000 concentrated solar power systems. That’s a heckuva lot of neodymium.

Speaking of the manufacturing challenges, Tim Carney notices an interesting NY Times report on a plan by China to defuse a potential solar-tech trade war with the US in the short run, while preparing for a longer political battle.  Just how “green” are solar panels in practice?  Not very, and not very efficient, either:

The manufacture of polysilicon requires enormous amounts of energy — so much electricity that it typically takes the first year of operation of the panel to generate as much power as was required to make the polysilicon in it. The process requires superheating large volumes of material in electric-arc furnaces, including the melting of quartzite rock at more than 3,600 degrees Fahrenheit….

China’s own polysilicon industry is controversial because it relies heavily on electricity generated by coal-fired power plants, and because weak environmental controls at Chinese polysilicon factories have resulted in toxic spills that have fouled streams and rivers.

China’s autocrats can get away with ruining the environment in the cause of “green” energy, but that doesn’t work out as well in the US:

Chinese manufacturers have studied moving solar cell factories directly to the United States but have largely rejected it in favor of other countries because it takes so long to comply with the many American regulations for opening new factories that use a lot of chemicals, according to a Chinese industry executive, who spoke on condition that neither he nor his employer be identified.

And China has a relative abundance in the rare-earth compounds needed for the manufacture of these panels, and the other so-called “green” energy technologies.  How about the US?  Er … not so much.  We would be even more reliant on foreign and rare resources than we are now in the fossil-fuel economy in which we currently live, so put some scare quotes around the notion of “energy independence” as a result of switching to “green” “renewable” energy, too.