Umm, what is the New Scientist talking about here?

Even if solar cells like this are eventually built and put to work, they will still contribute to global warming. That is because they convert only a small fraction of the light that hits them, and absorb most of the rest, converting it to heat that spills into the environment. Sustainable solar energy may therefore require cells that reflect the light they cannot use.

Umm, Eh?

Consider a rock, sitting in the sunshine. Photons hit it, yes. If it\’s dark rock, most are absorbed, not reflected. That\’s why rocks get hot on a sunny day, because the photons are turned into heat.

So now we have a special rock, a solar cell. Some of those photons that would have been absorbed, become heat, are now going off and making electricity. So, err, we\’ve got less heat than if we just had rocks instead.

It seems that the New Scientist is thus trying to tell us that it\’s rocks that are responsible for global warming. Presumably we just paint the whole place white then?

10 thoughts on “Umm, what is the New Scientist talking about here?”

  1. Actually, the affect of the planet getting whiter (EG more snowfall) is one of the big unknowns in climate change.

    It’s fairly well documented that while overall temperatures rise, north west Europe in particular will get colder. What’s not known is how the resulting snowfall may affect or counter the warming trend in the mid term.

    There’s evidence to suggest that ice ages are preceded by warmer periods which result in localised cooling which snow-balls (pardon the pun) out of control.

  2. Do all journalists have to fail an IQ test?

    Anyway, why not build a panel combining solar voltaic and pipes-of-water-heating? That way you could economise on manufacturing, scaffolding and installation costs and so on, and you’d get any advantage there might be from keeping the cells cooler.

  3. And you wonder why so many of us are unconvinced of this whole global warming thing on the scientific level as well as the economic level?

  4. solar panels reflect and so do rocks…
    every bit of energy absorbed by solar panels turns into heat(including the electric part)..
    the question is : do solar panels reflect more than the avg rock…or not??

  5. It depends on where the solar panels go. If they ate dark and sit on white rooftops then they will add to heat absorption. If they go on typically dark British roofs the effect is likely to be minimal. There those, Stephen Chu included, who think painting things white is part of the solution to the global warming thing

  6. More generally, albedo matters. Anything that raises the albedo of the Earth will increase energy reflected into space, and reduce the energy left to be added to the planet. And the more efficient the solar panel, the more this is true, since a 100% efficient panel would reflect no energy at all…

    Anyhow, it’s true that building an acre of solar panels with a low albedo on top of somewhere with a high albedo would – technically – increase the energy being added to the system, and thus global warming.

    But uh….just thinking about it in my head, I don’t think the sums add up. The impact on global albedo is likely to be imperceptibly small (and it isn’t even obvious it would be, on balance, negative). I just don’t see if really mattering…but if it DID, we could just start offering “albedo credits”. Firms could go paint a couple of square kilometres of desert white, and sell certificates for each square meter; every time you put up a square meter of solar panels you’d go and buy a square meter of albedo credits to offset it. Problem solved for the cost of a little paint and some paperwork. 🙂

  7. They sound like a superb heating system to me. They take energy from sunlight and create more energy from it. My knowledge of physics is shaky, but doesn’t that break some Law or other?

    Regarding the comment that it is commonly thought that NW Europe will get colder because of AGW – weren’t winters meant to get milder, not colder? Has the settled science changed 180 degrees?

  8. This mistake was in Superfreakonomics, I think.

    Btw, the idea that things that get hot can be used for heating is a great one, and often works, but a lot of the time (including in homes) the pattern of electricity use is not the same as that of heating or hot water.

  9. I think painting things white is one of Bjorn Lomborg’s hobby horses, too … at least in that If-you’re-gonna-do-x-you-might-as-well-do-y-because-it-achieves-the-same-thing-more-cheaply approach of his.

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