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posted by LaminatorX on Sunday November 09 2014, @12:52AM   Printer-friendly
from the hot-wheels dept.

Several sites are running a story on the solar roadway installation in the Netherlands, including phys.org and IFLScience.

However over at EEV Blog is a thorough critical review by Dave Jones which runs through the numbers and finds it doesn't add up as a practical proposal. There's references to Dave's original review of an earlier proposal, for some background on the calculations.

From the associated forum posting:

Dave shows how to go about doing ballpark engineering feasibility calculations for such a project, calculates the expected payback period, and SPOILER, shows why Solar Roadways will never be a viable technology. This time using real measured data from the Netherlands cycleway prototype, and real measured solar insolation data for the Netherlands

 
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  • (Score: 2) by tonyPick on Sunday November 09 2014, @10:46AM

    by tonyPick (1237) on Sunday November 09 2014, @10:46AM (#114240) Homepage Journal

    The problem is he doesn't compare the cost to what it would have cost to pave the cycle way with an ordinary tarmac surface.

    I thought he covered this in his comparison of construction costs (skip to 1280 seconds). Specifically the source data is at: http://www.worldbank.org/transport/roads/c&m_docs/kmcosts.pdf. [worldbank.org] (Note that the Rehab cost to install the road and maintain the panels is considerably higher than standard road maintenance costs).

    The associated forum talks a the specific numbers around here: http://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg545930/#msg545930. [eevblog.com]

    And even in the case where you're repaving a road it's still just better (way cheaper, far more power) to stick the panels on a nearby roof or raised/angled surface, rather than the floor, as long as you have roof space available (and we still have lots of that). Now when you run out of roof space _and_ this is considerably cheaper then maybe, but I don't think we're even close to that yet.

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  • (Score: 2) by mojo chan on Sunday November 09 2014, @01:45PM

    by mojo chan (266) on Sunday November 09 2014, @01:45PM (#114263)

    Those stats are for roads, no cycle ways.

    --
    const int one = 65536; (Silvermoon, Texture.cs)
    • (Score: 2) by tonyPick on Sunday November 09 2014, @02:29PM

      by tonyPick (1237) on Sunday November 09 2014, @02:29PM (#114269) Homepage Journal

      Yep - but I can't find any evidence that different cycle way costs will significantly change the ballpark - at least to within an order of magnitude:

      i.e. from: http://www.aph.gov.au/parliamentary_business/committees/house_of_representatives_committees?url=primind/rdinq/sub54-e.pdf [aph.gov.au]

      A typical off-road cycleway costs around $100k per kilometre to construct.

      That's lower than the initial estimates based on the road figures (original 172K euro/km, $100k (Australian) is about 69k euros), so the roadbuild cost per m^2 drops... by 13 euros to 9 euros, and the total build cost from 292 to 279.

      We're still nowhere near the 150 euro mark we need to be to be around a rooftop system (at which point we start to worry about maintenance), and still at near enough to hit the "twice as much for a quarter of the output" result given the number of other assumptions baked in.

      • (Score: 2) by mojo chan on Sunday November 09 2014, @02:58PM

        by mojo chan (266) on Sunday November 09 2014, @02:58PM (#114275)

        Err... 69,000 euros per 1000 metres is 69 euros per metre. I don't know where you got 9 from.... That's actually a rather low estimate, at least for Europe: http://transportretort.wordpress.com/2011/02/09/how-much-would-cycle-paths-cost/ [wordpress.com]

        By the time you have added maintenance on top to match Dave's figures a solar cycle path makes sense.

        --
        const int one = 65536; (Silvermoon, Texture.cs)
        • (Score: 0) by Anonymous Coward on Sunday November 09 2014, @05:14PM

          by Anonymous Coward on Sunday November 09 2014, @05:14PM (#114291)

          69,000 euros per 1000 metres is 69 euros per metre.

          You don't care about per metre - you care about per square metre. So the "9" figure is actually "about 40%" of the construction cost for Rehabilitation work, which rather generously assumes that the equivalent width holds to TFA figures (which are very generous to start with). In practice the cycle lane won't be as wide, and your cost per square meter is actually pretty high, which actually makes the numbers for the cycle path lightway even worse than those for the road case.

          By the time you have added maintenance on top to match Dave's figures

          What do you think the MTBF per solar cell is? For the rooftop system the MTBF is high, and the maintenance cost very very low.

          Look, you're competing with a total lifetime cost (from TFA) of 150 Euros over about 15 years by slapping a panel install on a roof next to the path. Just fitting the lightway has cost you twice that, your maintenance costs will be higher and can only add to that figure, and you're recovering a quarter of the electricity to offset the initial costs. Practically they need to demonstrate very low maintenance and hit an install cost of less 40 euros per square meter for the baseline install on the path to even get close to rooftop. Not. Going. To. Happen.

          Look - if you want to publish a TCO calculation with maintenance offsets over failure rates versus energy harvest then I could be persuaded, but so far by the numbers you're not even close.