How Sustainable Is Stored Sunlight?
lowtechmagazine.com
lowtechmagazine.com
> The average solar insolation in Arizona is 1,964 kWh/m2/yr (in Phoenix). If we assume a solar PV efficiency of 15%, one m2 of solar panels would generate at most 295 kWh per year. Consequently, almost 68 square kilometers of solar panels (6,800 ha) would be required to power the factory -- a calculation that also relies on the assumption that solar energy is equally distributed throughout the days and the seasons (or stored in batteries), and that there's no open space between the panels. Remarkably, Tesla shows an illustration of the factory with solar panels on the roof. Knowing that the factory will occupy a surface of 1 ha, while 6,800 ha of solar panels is required to run it on renewable energy, Tesla's claim is an obvious example of greenwashing -- and everyone seems to buy it.
I think this is a very uncharitable interpretation of that 'illustration'. The illustration makes no explicit claim that the energy is produced by the solar panels on the roof, let alone solar power. And I think it goes without saying that heavy industry cannot be supported by a small cluster of panels. There are even wind turbines in the picture, which further discredits the idea that Musk is trying to imply the solar panels can do it alone.
Assuming their input data is actually correct, I will speculate they are calculating the energy cost of the entire lithium battery production from raw materials, such as extracting lithium from mineral deposits, the majority of which would happen before the materials arrived at the Tesla factory.
I also expect Elon Musk knows what his electricity bill is. Given his investment in green technologies and his general success in delivering projects, I would be rather surprised if he advertised a solar factory if there was a chance he would be out by 4 orders of magnitude on how much power he would need.
And also inflates that amount of greenwashing involved...... Why crow over renewable energy when your use of energy is irrelevant relative to your suppliers?
So, your solar roof drops from 100% 'green' to 99.9% 'green' that's hardly a real issue.
South America to China to California vs Nevada to Nevada to Nevada.
You will not find your magical technology in shipping.
Additionally ocean shipping is cheap enough that it can take less energy to ship something to the other side of the world than to the other side of Nevada.
It seems that the drying process is the one to target as it accounts for around 50% of the energy budget and uses big electric ovens. Electric ovens are something that respond very well to economies of scale though, given the losses are a function of the volume versus the surface area, so you could see significant reductions there with a factory this size.
If you look at one of their sources[1], it is clear that this is the case.
[1] http://www2.epa.gov/sites/production/files/2014-01/documents... p.65
It may just be flat-out wrong, which is unfortunate.
[0]: http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook...
Reno, NV is where the plant is being built. Not sure why that isn't being used as the location: (about 6.5kWh/m2/day = 2370kWh/m2/year)
But yeah, they will probably not produce more than 20% of their needs with these solar panels.
http://cleantechnica.com/2014/09/12/tesla-gigafactory-huge-2...
If he got that wrong (which seemed obvious to me from the picture of the Gigafactory alone), who knows what else he got wrong.
It's smart positioning by Tesla to show solar power for the factory but it certainly will still be connected to the grid.
Important takeaway: A solar cell embodies a huge amount of energy, yet can be shipped. Make solar cells in places with lots of clean energy and ship them elsewhere.
What about the energy use and carbon emissions from shipping?
Shipping is negligible and when compared by energy per tonne per km, can be up to almost 100x better than road, so going 200km by road can compare to going nearly 20000km by sea in some cases.
Putting everything in one place could get savings from many factors, but transport doesn't appear to be that major compared to the others.
The 20,000 GWh figure is clearly bollocks, one factory a hectare in size is not going to be using the same amount of electrical power as the whole of Nigeria.
edit - also, one thing I do not understand with their argument, is if Tesla's illustration is really supposed to show that the factory can run entirely on rooftop solar, why would it feature around 100 large wind turbines dotted all across the hillside?
The total embodied energy is going to get absolutely slashed.
edit - btw, I accidentally fat fingered the down button on your comment that had the link to - http://www.withouthotair.com/ - sorry. I hope that isn't what prompted you to remove the comment.
I'd re-read the withouthotair site the other evening after seeing Elon's presentation, as he made a similar case regarding the area of the USA needed to be powered by solar. I was a bit bummed out by the conclusion for the UK and wondered what the global equivalent was, as the UK is low on solar. I then noticed I'd skipped a chapter that does the rough calculations for other regions (http://www.withouthotair.com/c30/page_231.shtml) the basic answer being that Solar may just save us, but it'll be an incredible amount of work, both political and engineering.
(Which is basically the same answer as for the UK, though in the UK solar is mostly replaced with wind/wave/hydro as we're relatively blessed with those).
There is already 30% efficient directly illuminated multi-junction PV on the market ( http://www.emcore.com/wp-content/uploads/ZTJ-Cell.pdf ), they are just so damn expensive at the moment that only the space industry are using them.
Also, while it is a huge amount of work, it is no worse than many other industries, the economics are starting to make it a good investment for big finance, and we are not likely to run short of either silicon or lithium along the way.
However, we already generate 7.5% of our energy from renewables and clearly 7.5% of the country isn't covered in windfarms/solar/biofuels. Therefore he must have made a mistake somewhere: if reality disagrees with theory, the theory must be wrong.
Roughly the output of the Hoover dam.
2.28 GW is the most you should ever write with that calculation. What you wrote went down to hundredths of a watt (if I can count).
Nobody should care about the third significant figure in such a comparison, much less the twelfth. The second digit is even of questionable accuracy. Strict significant figure rule following isn't important in casual contexts, but deciding which digits are actually relevant is imporant. Is accounting for leap days really important here?
Also, the output is roughly the installed maximum capacity of the Hoover dam, but about 5 times larger than it's actual yearly production.
> In order to fill these gaps [ night, cloud ] , a storage solution
> or a backup infrastructure of fossil fuel power plants is required
> -- a factor that is often ignored when scientists investigate the
> sustainability of PV systems.
Note they did say 'solar power', not 'solar cells / PVC / etc'. Solar thermal plants ride through periods of cloud, and well into the night, reasonably well. But the big problem is that assumption that you must either store solar, or you burn coal / oil ... followed by a complaint that scientists ignore important factors.
Are you saying that solar thermal is enough storage for a predominantly solar grid? I'd suggest it isn't. I'd also suggest that solar thermal is a type of storage solution and it's time-shifting properties are one of the things that make it useful.
My point is that this is either a flawed or a disingenuous premise.
There's myriad ways we could deal with gaps in sunlight availability: nuclear fission (not a fan, but undeniably one way), biofuels (also not a fan, but ditto), reduced demand / opportunistic usage patterns (to ameliorate the effect - not easy, but disturbs me that questions about energy usage never include 'reduce' or 'adapt' in the list of considered answers), and, most importantly, a stack of renewable options that are not constrained by the vagaries of sunlight -- geothermal, wind (terrestrial and tethered), wave, tidal, and hydroelectric spring to mind.
So your plan is to turn the electricity off at night?
Read the original article. Read my original response.
Almost as an aside -- electricity does happen to be available a good way into the night with solar thermal.
But the big point (again) is that it's not a matter of 'solar + batteries' as the only option to burning fossil fuels.
I can buy 18 35Ah 12v AGM batteries, plus 0 AGW conductors, for about $1350. That's 7.5kwh for $1350.
What exactly defines the "good deal" argument I keep seeing?
The price for the 10 kWh model is basically 50% of what everyone was expecting, which is what has everyone excited. You don't often see a 50% drop in price in systems that are this closely followed.
No, you are not. You are actually going to buy five times as many batteries and work in the 20% of the storage range which is suitable for continual cycling. So that's 90 batteries off the bat, or about $6750, almost double the cost of the Powerwall, not including the ancillary equipment you haven't budgeted for to bring your batteries into the same league as the Powerwall.
You still need the battery room to install them in, and the fire protection system to put out electrical or chemical fires when things go wrong.
The Powerwall includes thermal and fire containment (the batteries are swimming in gel), the Powerwall also takes care of the "battery room" issue by storing the battery in a container on the wall.
For those with greater power requirements, there are rack mounted power cells, again with thermal and combustion mitigation already in place.
The integration and packaging is why everyone is excited about these batteries at this price.
It also means that if you want your batteries to last, you can reduce your depth of charge by purchasing excessive capacity. This way instead of discharging 100% of X capacity, you can discharge 50% of 2X capacity, and this lower discharge depth makes the battery last longer. Which means you tend to have to buy a lot more capacity than li-ion.
Beyond that, look at it like any system. e.g. do you want 4 small fridges that give you x liters of volume, or one large fridge that gives you 4x liters of volume for a slightly higher price? Do you want 10 harddrives that give you 100gb each for $250, or would you buy a $300 1 TB drive?
There are non-financial reasons to go for simplicity, something that works out the box, plug and play. Especially for consumer grade equipment. Beyond that, Tesla's solutions offers some integrated solutions e.g. concerning fire hazards that you'd need to do yourself otherwise. And lastly, it appears batteries benefit from economies of scale. Their battery is already for sale today, and considering the factory they're building, it's quite exciting to see how cheap batteries will get by 2025, but that's a different story.
I get that it should be part of a much larger plan, but Solar in its current iteration doesn't seem like that safe of a bet.
I would move, if that scenario was more than once every other decade!
Come on man. There's more to it. There are real challenges and a volcanic ejection certainly is one of them, it's just not anywhere up the list.
It's the responsibility of the world's governments to work out ways to keep the grid-connected solar solutions working. Maybe change the 'Net metering' rules to buy the solar power from customers at a lower price, and let the supply-demand work itself out.
It'll be very stupid if we let go a well-functioning grid based solar power solution just because some power distribution companies don't find it profitable.
It won't be that simple, since even this (allowing customers to contribute power back to the grid at scale) requires expensive infrastructure upgrades.
IMHO, smarter grids are much better than batteries all over the place.
Whereas there is a limit to the maximum intelligence of refrigerators, airconditioning devices, heat pumps, and washing machines.
Other countries might manage smarter grids but it's not (yet) politically feasible in the US.
My brother came home from elementary school one day telling us how modern electricity production causes pollution (sure, that's true) and if we'd go back to powering our society by burning wood, the way people did it in ancient times, we wouldn't have the pollution.
Burning wood, of course, causes plenty of pollution; a major way to see the decline in civilization after the fall of Rome is to notice how the level of particulate pollution from fires cratered. If we were to produce the same amount of power we produce now, but from wood instead of coal and oil, our pollution situation would be much worse. Also, we'd quickly run out of wood.
I think people today have imprinted on the message "coal and oil production of electricity is bad". Making your own batteries from a non-fossil-fuel source isn't a way of powering your home more efficiently, or of reducing pollution, it's a way of refusing to partake in coal consumption -- the hijab of the environmentalist movement.
Many people, particularly starry eyed young ones fresh from academic nurturing, fail the test badly.
Most govt's time horizon is about 5 years. We are doomed.
---
edit - Actually, to be honest, I do not think in this case I am being overly cynical. The article I linked to, titled "The ugly side of solar panels" starts with:
"New research shows, albeit unintentional, that generating electricity with solar panels can also be a very bad idea. In some cases, producing electricity by solar panels releases more greenhouse gases than producing electricity by gas or even coal."
This claim is then not really addressed till right at the end of the article, where we find the following:
"For rooftop and ground-base installations, the eco-friendliness can be good or doubtful, depending on the solar insolation and the life expectancy. But if we consider solar panels mounted on gadgets like laptops or mobile phones, solar energy becomes a plainly bad idea.
If we take a life expectancy of 3 years (already quite optimistic for most gadgets) and a solar insolation of 900 kWh/m² (quite optimistic too, since these things are not lying on a roof), the result is 1,038 gram CO2 per kWh in the worst case scenario (high-efficient mono-crystalline cells produced in the US). That means that it is better for the environment to power a gadget with electricity generated by coal, rather than by a solar panel."
So, if you buy a laptop or mobile with a solar panel on it and then throw it away after three years, then it is worse than coal.
Which is obviously a completely rational point to make on the subject, given all those masses of mobile phones and laptops sold everywhere with solar panels on them.
Then it gets even better:
"All this does not mean that PV solar energy should not be promoted. For one thing, it’s much better using silicon wafers to make energy generating equipment instead of energy guzzling equipment (like computers, mobile phones and car electronics)."
And by this point I am not sure if this is satire, or if the author thinks their website is hosted on a steam powered abacus.
Actually, now that I think of it, I can't remember ever seeing a laptop with its own coal fired power plant. I wonder why this isn't done?
http://rameznaam.com/2015/04/14/energy-storage-about-to-get-...
That said, I did own a Sony laptop that had a battery saver option where it would limit the charge to 80% in order to prolong battery life. I can't remember if this actually meant "displayed charge = real charge - 20" or was capping the charge to 80%
Marine li-ion batteries advertise 2000 full cycles (80% depth of discharge). Electric cars have 10 year battery warranties. Etc.
Unless the linked article is talking about lithium iron phosphate technology. That is more durable than standard LiIon technology.
But that isn't in wide use, despite its initial promise.
AppleCare on their laptops stops being valid after 1000 cycles. I don't know what DoD they use for their calculation though.
> In order to fill these gaps, a storage solution or a backup infrastructure of fossil fuel power plants is required -- a factor that is often ignored when scientists investigate the sustainability of PV systems.
Um. Pardon? Either he's having an argument with himself, or he's reading some pretty lame journals. Or is he just confused? Let's see:
> Obviously, this strategy requires a backup of fossil fuel or nuclear power plants that step in when the supply of solar energy is low or nonexistent. To make a fair comparison with conventional grid electricity, including electricity generated by biomass, this "hidden" part of the solar PV system should also be taken into account. However, every single life cycle analyse of a solar PV ignores it. [3, 2].
Yeah, okay. That's a perfectly debatable paragraph. So let's see the science behind the claim: [2] has nothing to do with anything! It addresses energy storage, but is not about energy storage; and it does NOT claim to be a literature review, nor does it claim to reference "every single life cycle analysis". Am I missing something? Is this citation of "[3, 2]" supposed to represent the entire sum of human scientific knowledge on this matter? Am I an idiot? Surely I'm the idiot, I didn't waste my time reading this article - that point must be shooting straight over my head!
Okay, let's read the paper. It's on energy payback/cannibalism - a logical presentation from what I skimmed - but is absolutely focused on the energy life cycle analysis of a whole technology experiencing rapid growth - Eg. nuclear back in the day - whereby the energy invested to rapidly establish new technologies may be greater than or at least massively offset any efficiencies (or indeed, "zero emissions") they may have over existing (think "sunk cost") incumbent energy production.
Which has nothing to do with central thrust of this article which seems to be that we should point and laugh at all those idiot scientists who forgot that the sun disappears each night!
But this writing forgets one thing - who is saying that PV (or wind for that matter) can replace established baseload power generators in a 1:1 swap?
Nobody sane, that's for sure. So I'll give you a hint: it's electricity buyers. They don't give a damn that they're destroying the planet by using PV solar, the fundamental fact is that in countries like Australia, even though you seemingly can't swing a cat without tripping over high-grade thermal coal ideal for cheap power, we pay among the highest electricity rates in the world. It's that kind of corrupted and/or government-regulated inefficiency that is the only thing to blame for the fact that PV solar can compete at all, even when subsidies are withdrawn.
I can't keep reading.