Ask Pablo

Could the U.S. meet its energy needs with solar panels alone?

Topics: Environment,

Ask Pablo

Dear Pablo,

I’ve read in more than one place that 100 square miles of solar panels in the U.S. would meet all our energy needs. Wondering if you thought this was accurate and, if so, achievable?

Wouldn’t it be great if we could completely switch from being a carbon-based economy to being a solar-based economy? The answer shouldn’t be too hard to find but the conclusions might surprise you.

Solar photovoltaic modules or panels convert beams of energy from the sun — photons — into electrons, which we can then use as electricity. According to Dan Berger, senior project designer at SPG Solar, we receive about 6.5 kilowatt-hours (kWh) per square meter of solar energy per day, or 2,373 kWh per square meter per year. At 12 percent efficiency, the solar panels generate 285 kWh per year. The average American used 12,000 kWh in 2003, so each person would need around 42 square meters of solar panels (about 450 square feet).

At 12,000 kWh per capita, electricity demand is roughly 3.6 trillion kWh, or the equivalent of 1,200 coal-fired power plants running full-time. To generate 3.6 trillion kWh per year, we would need to install about 12.5 billion square meters of solar panels, or around 4,883 square miles. This is clearly a lot higher than the number that you had heard; about 70 x 70 miles.

If we assume we can find enough land for all of those solar panels, would a project of this scale be achievable? A typical solar panel contains between 800 and 1,570 grams of silicon (the high-grade material with which solar panels and computer chips are made) per square meter. If we assume an average of 1,185 grams, we would need 14,812,500 metric tons of solar-grade silicon. The projected annual production of silicon by 2012 is 144,000 metric tons, which means that it would take over 100 years to meet our needs of silicon to make all those solar panels! And that is if we assume a complete freeze on computer chip manufacture and solar panel demand in the rest of the world.

You might say that silicon supply rates will increase in the future, but so will the demand for electricity. Fortunately new solar photovoltaic technologies are coming onto the market, and use materials other that silicon, like cadmium telluride and copper indium gallium selenide.



But there is another problem: The sun doesn’t shine all day. To get around this problem, we could build a global electricity grid and, since the sun is always shining somewhere, we should be able to get enough electricity. But this sort of dream project would require a very large investment and may not be technically — or politically — feasible for many years to come. For now, a sensible solution would be to store surplus solar energy generated during the day, and use it for off-peak hours (nighttime). That could be done by pumping water into uphill reservoirs, so that the energy can later be retrieved through hydroelectric turbines, as in a hydroelectric dam.

While it is clear that solar photovoltaic is an important component in the basket of renewable energy technologies, it can’t be the only one. Wind, geothermal and wave power will play an increasing role in meeting our needs as well. Another option would be to pair solar energy with wind and biogas (natural gas produced by the microbial decomposition of agricultural waste). In fact, a recent study in Europe showed that Germany has sufficient wind, solar and biogas resources to feed that nation’s electricity needs, even when the wind is not blowing or the sun is not shining. By diversifying our renewable energy technologies we ensure a continuous supply of clean energy.

Got a question about the environment? Ask Pablo at AskPablo@Salon.com.

Got a question about the environment? Ask Pablo at AskPablo@Salon.com.

Featured Slide Shows

  • Share on Twitter
  • Share on Facebook
  • 1 of 11
  • Close
  • Fullscreen
  • Thumbnails
    Burger King Japan

    2014's fast food atrocities

    Burger King's black cheeseburger: Made with squid ink and bamboo charcoal, arguably a symbol of meat's destructive effect on the planet. Only available in Japan.

    Elite Daily/Twitter

    2014's fast food atrocities

    McDonald's Black Burger: Because the laws of competition say that once Burger King introduces a black cheeseburger, it's only a matter of time before McDonald's follows suit. You still don't have to eat it.

    Domino's

    2014's fast food atrocities

    Domino's Specialty Chicken: It's like regular pizza, except instead of a crust, there's fried chicken. The company's marketing officer calls it "one of the most creative, innovative menu items we have ever had” -- brain power put to good use.

    Arby's/Facebook

    2014's fast food atrocities

    Arby's Meat Mountain: The viral off-menu product containing eight different types of meat that, on second read, was probably engineered by Arby's all along. Horrific, regardless.

    KFC

    2014's fast food atrocities

    KFC'S ZINGER DOUBLE DOWN KING: A sandwich made by adding a burger patty to the infamous chicken-instead-of-buns creation can only be described using all caps. NO BUN ALL MEAT. Only available in South Korea.

    Taco Bell

    2014's fast food atrocities

    Taco Bell's Waffle Taco: It took two years for Taco Bell to develop this waffle folded in the shape of a taco, the stand-out star of its new breakfast menu.

    Michele Parente/Twitter

    2014's fast food atrocities

    Krispy Kreme Triple Cheeseburger: Only attendees at the San Diego County Fair were given the opportunity to taste the official version of this donut-hamburger-heart attack combo. The rest of America has reasonable odds of not dropping dead tomorrow.

    Taco Bell

    2014's fast food atrocities

    Taco Bell's Quesarito: A burrito wrapped in a quesadilla inside an enigma. Quarantined to one store in Oklahoma City.

    Pizzagamechangers.com

    2014's fast food atrocities

    Boston Pizza's Pizza Cake: The people's choice winner of a Canadian pizza chain's contest whose real aim, we'd imagine, is to prove that there's no such thing as "too far." Currently in development.

    7-Eleven

    2014's fast food atrocities

    7-Eleven's Doritos Loaded: "For something decadent and artificial by design," wrote one impassioned reviewer, "it only tasted of the latter."

  • Recent Slide Shows

Comments

0 Comments

Comment Preview

Your name will appear as username ( settings | log out )

You may use these HTML tags and attributes: <a href=""> <b> <em> <strong> <i> <blockquote>