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Cake day: June 26th, 2023

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  • …i’ve only done urban installations, but recently i’ve been giving a lot of thought to the localised effect of high-albedo reflective roofs (and other materials) and transpirative tree canopies (and other vegetation) being replaced by low-albedo solar photovoltaic arrays: it measurably increases heat load on the local environment, reduces radiative cooling at night, and drives up overall cooling demand, which presents a deep rabbit-hole of cost-benefit analyses in the tradeoff between reduced grid use during the day versus increased grid use at night, the potential net reduction in carbon emissions therefrom, the added carbon emissions from manufacturing and maintaining solar photovoltaic infrastructure, and the loss of ecosystem carbon capture and biodiversity services from decreased solar exposure and increased heat island effect…

    …it’s a poorly-understood subject of ongoing academic study in both urban and natural environments, with the largest arrays i’ve read subjected to that sort of rigorous analysis measuring on the order of 1/300,000 the scale of this proposed project…still, apples-to-apples, that larger study was performed in desert scrubland and measured about 4°C increased local temperatures, which is significant but not a good proxy for the weather effects one would see generated by a 750 square-mile convection cell over truly barren desert…

    …back to your original question, most solar photovoltaic panels loose somewhere on the order of ¼ to ½ percent efficiency per °C incease in panel temperature, but like most things in the real world it’s actually much more complicated than a simple multiplier…the short version is that investors wouldn’t be building desert arrays if they didn’t present a short-term economic gain, and they certainly do provide plenty of power despite the increased heat, but the long-term environmental impact of radically altering surface albedo at such a large scale isn’t well-understood relative to the implied let alone actual changes in carbon-intensive energy generation…









  • …my experience before ‘high-efficiency incandescent’ halogens was the same: i have thirty-year-old proper halogen lamps either still going strong or which have been replaced only once over that period…these little A19 halogens, though, have an such absurdly-short duty cycle that they’re viable only by virtue of stocking up dozens of cases for pennies on the dollar when they were phased out a couple of years ago…

    …i do hope that we have respectable consumer bulbs available in perhaps five years after those few hundred halogen bulbs are gone, but i’m not optimistic as poor spectra appear inherent to LED technology and the market seems to have settled on ‘good-enough’…proper incandescent bulbs are of course still available for specialty applications, but they’re not easy to get…


  • …the contractor-grade FEIT incandescents installed when we built our house enjoyed a MTBF of about five years; the FEIT halogens (‘high-efficiency incandescent’) i stocked up to replace them after traditional incandescents phased out are on the order of six months MTBF…

    …while i question whether the manufacturing and distribution of ten fourty-watt halogen bulbs really emits less carbon than one sixty-watt incandescent running for the same duration, at least the spectra are unchanged: i’ve yet to find any LEDs which offer acceptable black-body spectra and i specify the things professionally…