Simanaitis Says

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POWER FROM OLD SOL

SOLAR POWER is a tantalizing concept. Sunlight is there half the time in many places, free for the asking.

Well, not exactly free, with some recent developments very promising and others that are disappointing. Here’s an overview.

There are two primary means of transforming sunlight into electricity, either concentrated solar power (CSP) or photovoltaics (PV).

CSP uses an array of mirrors and lenses that focus sunbeams to concentrate their heat. From this point on, concentrated solar power operates like a conventional power plant: A working fluid, typically water, is heated by the focused beams and drives a turbine that generates electricity. CSP is akin to a hydroelectric dam’s water pressure or a nuclear plant’s heat of fission.

By contrast, photovoltaics technology performs a direct conversion of sunlight into electricity through semiconducting materials embedded in solar cells. These are the familiar arrays of shiny panels seen on roofs and also employed on space craft. PV solar arrays can be vast as well, these facilities producing outputs comparable to those of CSP plants.

Spain leads the world in CSP, with 11 power stations in operation.

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Solnova Solar Power Station, outside Seville, Spain, has three concentrated solar power units, two of which are shown. Image by Koza1983.

One of Spain’s larger facilities is the Solnova Solar Power Station outside Seville, in the south of the country. Its three units were completed in 2010 and produce a total of 150 Megawatts capable of supporting more than 25,000 homes. (As a rule of thumb, depending upon locale, 1 MW of electricity is sufficient for perhaps 150 to 200 homes.)

The Ivanpah Solar Power Facility, in the Mojave Desert of California, was designed to be the world’s largest CSP plant producing 377 MW.

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Ivanpah’s eastern boiler tower is visible from nearby U.S. Interstate 15, 225 miles northeast of Los Angeles, about three-quarters of the way to Las Vegas, Nevada.

Ivanpah has not been without controversy (see http://goo.gl/VgS6cC). Scorched birds angered environmentalists. What’s more, Ivanpah’s average output since it went on-line commercially in December 2013 has been only about one-quarter of the anticipated amount.

One problem is an inherent aspect of solar power: Some days are sunnier than others. However, even Ivanpah’s production in sunny May through August was 40 percent below target. Operators requested and were granted an allowance to use 60 percent more natural gas in auxiliary boilers, this fossil-fuel addition hardly enhancing the facility’s image.

Photovoltaic technology has been one of incremental enhancements of efficiency and reductions in cost. Today, a typical production solar cell has a PV conversion of between 12 to 18 percent. Advanced technology (cells spelled with $$$) have improved on this, some with efficiencies as high as 40 percent.

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Photovoltaic solar panel. Image from ScienceDaily, http://goo.gl/Jp0haN.

The latest PV news is from Australian researchers at the University of New South Wales. They report efficiency of more than 40 percent with conventional solar cells, a result that’s been independently confirmed by the U.S. National Renewable Energy Laboratory. (For background on NREL, see http://wp.me/p2ETap-n3).

The Australian achievement makes use of optical bypass filters that are said to fine-tune solar energy otherwise wasted. These filters permit the focusing of particular wavelengths while reflecting others.

That is, akin to CSP, the idea is to direct concentrated beams of sunlight. Here, though, the beams are filtered and focused onto solar panels, not used merely as heat sources.

With either approach, the intermittency of sunlight requires storage and transmission of electricity, each a significant challenge of efficiency and cost.

Proponents predict an equality—without subsidies—of solar power versus that of the conventional U.S. grid by 2015. Hedges on this grid parity involve costs of conventional energy, environmental aspects affecting these costs—and predictable sunshine.

Thus far, my interests in solar power have been confined to the technical, not the financial. ds

© Dennis Simanaitis, SimanaitisSays.com, 2014

4 comments on “POWER FROM OLD SOL

  1. JJ Hepp
    December 19, 2014

    Hi Dennis,

    Another very interesting post! I’m an R&T reader familiar with your past writing there, stumbled across your blog about a month or so ago, and have been enjoying it ever since. I really like the diversity of topics you touch on.

    I found this to be informative and a nice exposure to the topic. While I try to follow alternative fuels, I have to admit I knew nothing about CSP before reading.

    I was surprised to see the 2015 date for equality – I thought this article (http://bit.ly/1w5lqbh) was hopeful at 2030. Or am I missing something?

    As a car enthusiast, I am torn when I read about cars diverging from internal combustion engines (http://bit.ly/13HuE7V). I appreciate the need to decrease reliance on fossil fuels – and support it – but there is just something missing from the Teslas of the world, most notably in the exhaust note arena. Maybe we’ll end up somewhere in between, where combustion engines are the exception (Tesla S nowadays) and fun electric/hydrogen/solar(?) powered cars are the daily drivers. Just as long as there is still that choice to be made…

    Anyways, thanks again and look forward to many more interesting reads!

    • simanaitissays
      December 19, 2014

      Many thanks, JJ.
      With regard to grid parity, the comment about 2015 came with those hedges noted. Hawaii, for instance, is said to have it already: locale, cost of getting fuel there, weather. Regulations play a profound role too: Anti-coal regs are, in a sense, a negative “anti-subsidy.”
      A complex issue indeed.

  2. Ed Kopacz
    December 28, 2014

    Hi Dennis: I ‘ve had PV Solar on my home at the Jersey Shore since 7/15/2014 and I have a 22 panel system generating a total of 5.4KW/day, max ( New Jersey. laws only allow one to install 110% of your previous years electrical use), and no night time storage is allowed.The system held its own powering my 2200sqft home this summer , and some days I was even ahead of my needs, including Air Conditioning. Come autumn, and until 1 November I was Head w/ ~ 350KW hrs in the “bank” . Once it started to become clouldy I ate into my “Bank”, and as of 12/25 I only had 71 KWH in the “Bank”. I lease my system from NRG Energy for 20 yrs at a cost of $64/ month, +~$2.20/mo grid fees (where last year’s electric bill averaged $94), I had no up front costs at all-NRG provided the installer , the solar panels and all the electrical equipment and necessary permits. System is guaranteed for 20 yrs, after which I could buy it for ~$4200, get another one or have it removed.So far it’s been a very good deal, in my opinion.

    • simanaitissays
      December 28, 2014

      Ed,
      Thanks for sharing your experience. Very interesting.

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This entry was posted on December 18, 2014 by in Sci-Tech and tagged , , , , .
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