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Comment by redcalx | Hacker News Reader

Have you factored in the CO2 footprint of solar panels? Producing pure silicon is energy intensive, then there are various metals involved, so you've got mining, refinement, smelting, and bulk transport costs. The panels also have a limited lifetime so you need to think about the disposal or recycling cost in 15-20 years. Pretty sure I've missed a load of costs too.

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This is calculated in energy return on energy invested (EROI). Solar is doing.. ok in that regard: http://rameznaam.com/2015/06/04/whats-the-eroi-of-solar/

The comparable number for fossil fuels (in this case, oil) is 'well to tank efficiency', which amounts to about 25% for oil, if i recall correctly. So 1/4th of energy contained in oil is already spent to bring it to market.

Notably, wind energy has a far more favorable EROI than solar does (currently), but wind power is a relatively limited resource.

To be clear, the article you link is arguing against the graph at the top.

> Solar panels, according to Weißbach, generate four times as much energy over their lifetimes as it takes to manufacture them. Unfortunately, Weißbach also claims that an EROI of 7 is required to support a society like Europe. [...] For solar, which I know better, this paper is an outlier.

> If we used only the estimates from 2010 on, we’d find an EROI for poly-Si solar of around 15. If we used only the 2013 estimate, we’d find an EROI of around 25.

> In summary: The Weißbach paper is, with respect to solar, an outlier. A more realistic estimate of poly-Si solar EROI, today, is somewhere above 10, and probably above 15. And it’s rising. Solar panels generate many times more energy over their lifetimes than is used to construct them and their associated hardware.

Wow. I suppose it should have been obvious, but it's still interesting to see nuclear's numbers so high, considering the enormous material requirements for reactors. Only makes me more sad that the world seems to be closing down nuclear rather than opening it up.

A large problem with current generation nuclear is that the easily obtainable uranium isotopes are in the process of running out (in no small part due to artificial limitations on e.g. reprocessing of fuel). We'll probably continue to have enough for some time to come, but a large-scale switch to nuclear energy is actually quite unlikely at this stage.

I don't mean to say that this is the primary reason for nuclear's demise - it isn't - but it is a real hurdle against increasing deployments.

Of course, there are very exciting new developments in nuclear technology that solve this - breeding, reprocessing, etc - but they are all (still) at an experimental stage. That's the catch-22 of nuclear: there's an existing, mature industry, which uses it's fuel unsustainably, and there are developments to sustainably use nuclear power, which is quite far from being an industry.

You probably also should include the CO2 footprint of energy storage/batteries if you plan on going 100% solar.

Wildly under-appreciated point. Many of those batteries die out quicker than you might think, and hold way less energy density than gasoline. Plus the environmental costs (much nastier stuff than CO2) of extracting rare earths and elements like lithium are huge. Since most of us on HN don't live in the global south or northwest China, we've never seen the breathtaking environmental devastation that brings us these "green" technologies.

breathtaking environmental devastation that brings us these "green" technologies

Again, this should be compared with the breathtaking environmental devastation of the non-green technologies. Most of us don't live in Appalachia (coal), Canada (tar sands) or Dakota (fracking) either. Or one of the two failed reactor exclusion zones in the world.

Seriously? For real? Lead acid batteries are extremely clean to recycle when done properly, and even though they have a short (~5-8 year life, depending on depth of discharge and cycle count) life, you simply drop into your local auto supply store to recycle them and pick up new ones.

We are literally pumping hundreds to thousands tons per day of CO2 in the atmosphere with coal, not to mention mercury and radium, and people are worried about batteries?

Tesla's Powerwall uses Lithium Ion batteries, so even if you are right, it doesn't apply in that case.

Could it be said that in order to gain the technology and production methods of a cleaner, more efficient energy source we must expend energy from dirty and inferior sources first? It seems to be the case; we go after the low hanging fruit or the fruit that we know we can do something with. If that is the case, then can that be seen as a optimistic outlook for human kind in regards to climate change? That in order for there to be a clean energy future we have to harness the energy sources available to us to get there.

No. Eventually renewable energy becomes a lower hanging fruit.

One thing to remember though is that there is a reasonable level of CO2 extras around generating traditional non-renewable sources (mining, transportation, materials to build the plant, maintenance of machinery etc).

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