[Discuss] Eclipses Re: Great talks last night, however...

[grg-webvisible+blu at ai.mit.edu (grg)]

On Sun, Jul 23, 2017 at 04:59:08PM -0400, Richard Pieri wrote:
> On 7/23/2017 3:42 PM, grg wrote:
> > In the paper they show that a conventional li-ion battery holds 90% of the
> > original charge after 3000 cycles (~9 years of daily cycling); and after
> 
> BS.
> 
> http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Hmm... did you look at the peer-reviewed journal article published in
"Advanced Energy Materials" in 2014 which is the one making the claim you're
calling BS (on the basis of "batteryuniversity.com")?  Here are those links
again for your perusing convenience:
  http://onlinelibrary.wiley.com/doi/10.1002/aenm.201401408/abstract;jsessionid=CBDD74C72BBF0C1C53B7FBB1AC2DB1B5.f04t03
  https://www.osti.gov/pages/biblio/1185480-solid-electrolyte-key-high-voltage-lithium-batteries

As for the "batteryuniversity.com" page which appears to have been written
in 2010, can you point at which part of it you think contradicts the
peer-reviewed article?  For one, I fear that "batteryuniversity.com" page
isn't reporting on the same battery technology; e.g. they say "Figure 1
illustrates the capacity drop of 11 Li-polymer batteries" but the numbers I
quoted from the journal article aren't measuring Li-po batteries at all,
they're measuring li-ion batteries with a liquid electrolyte (not polymer).
Indeed, the whole point of that journal article is that the choice of
electrolyte is critical for battery longevity.

Second, the "batteryuniversity.com" article is showing numbers for 1-hour
charge and discharge cycles, while the journal article is showing numbers
for 10-hour charge and discharge cycles, much more relevant for solar power
storage.  Cycles as short as 1 hour significantly reduce the lifetime of
these batteries; even that batteryuniversity.com page warns not to go
any faster than 1 hour.

My takeaway here is that when engineering solar power storage I'd pick the
2014 liquid electrolyte batteries the journal paper used as a baseline
instead of the 2010 Li-polymer batteries that batteryuniversity.com
reported on, and use ~12 hour charge and discharge cycles.


> > Nor do those characteristics describe millions of homes and buildings.  How
> > many buildings do you think are destroyed in Kansas by tornados each year?
> > Hundreds, for a survival rate of 99.99%.  So no, it's not because cows are
> > running away from approaching tornados or because they're sharing Farmer
> > John's storm cellar, it's actually because 99.99% of the spots in Kansas
> > don't have a tornado land on them.
> 
> The size of a home or even a large barn in rural Kansas is a tiny
> faction of the size of a 150km^2 (say) power station. Rural homes in
> Kansas are spread out dozens to hundreds of kilometers apart. So when a
> tornado touches down the chances of hitting a given home is small and
> the chances of it hitting several is practically nil.
> 
> Unless it hits Topeka.
> 
> That 150km^2 power station? That's the size of Topeka which got
> clobbered by a sequence of tornadoes in 1966.

Yes, that was an awful awful natural disaster in the middle of the last
century - claimed to be the 7th most damaging tornado event in all of
recorded history.  Of the 50,000 homes in Topeka at the time, almost 850 of
them were destroyed and 3,000 were damaged in some way.  So ~2% of homes in
Topeka were destroyed, and ~6% had some damage.  Of the 900,000 homes in
Kansas at the time, that's ~0.1% destroyed, so only 99.9% survival rate of
homes in Kansas for that year instead of the long-term average of 99.99%.
Terrible for those who fell into that small percentage (and even worse for
the 17 people killed, giving a human survival rate of only 99.99% in Topeka
and 99.999% in Kansas); but with this outcome for one of the worst tornado
disasters of all time, I still feel the cows and corn and solar panels have
the odds in their favor.


> > I guess you'll be surprised to learn that the ground is actually an
> > effective heat sink; see the ground loops in heat pumps, which provide air
> > conditioning by sinking the removed heat into the ground.  Here's a source
> > for you:  https://energy.gov/energysaver/geothermal-heat-pumps
> 
> The ground can hold a lot of heat energy but it doesn't conduct it much.
> That's why a GHP spreads its ground loop system out across a large area.
> You're not getting that from burying big battery packs unless you also
> install the same kind of extensive ground loop system which costs to
> install and maintain.

Look at it this way: if you put a battery in the ground underneath a solar
panel, the warming of the ground from that battery is going to be strictly
less than the warming of the ground from the sunlight hitting it directly
before the solar panel was installed.  With an 85% charge/discharge
efficiency, the ground is being warmed only 15% as much as under direct
sunlight.  Since there wasn't runaway heat buildup under sunlight, only 15%
of that amount of heating is also not going to exceed the earth's ability
to sink the heat away.

Taking a step back, you don't really think that keeping a battery in its
operating temperature range is going to be an insurmountable technical
obstacle, do you?


> Can ground-based work? Maybe. I don't think so. But even if it can be
> done? It's still just a stop-gap being marketed as a solution by a man
> who has a vested interest in selling batteries.

I get that you don't want it to work and especially don't want Elon Musk to
make any money off it, but are there any remaining technical problems which
cause you to say you don't think this is technically feasible?  To recap, in
this thread we've established many technical reasons it can succeed:
 * 0.15% of land in the continental US (10,000 km^2) is all that's needed
   to provide all the electricity consumed in the US
 * you'd need an additional 0.02% of land if you put all the panels on the
   NY/VT Canadian border
 * but the Nevada and southern California deserts might be a better choice
 * battery storage only adds 15% to solar power generation needs
 * batteries last for many thousands of 12-hour charge and drain cycles
 * temperatures underground are moderate and stable; batteries housed there
   put much less heat into heat the ground than the sunlight would
 * electric vehicle batteries work pretty well even above ground in cold
   snow and in hot deserts
 * the Great Plains are large, flat, and exist in the North
 * as an annual average, 99.99% of things (corn, cows, houses, etc.) in
   Kansas aren't destroyed by tornados; and in the worst tornado disasters
   in history that goes down to only 99.9%.  (this was part of a technical
   discussion on solar power feasibility? seriously?)
 * solar panel installations scale up and down pretty nicely; the total of
   10,000 km^2 can be in one or across millions of sites, and either will
   still provide all the electricity consumed in the US.

Given these facts I don't see it as a stop-gap at all; rather, I see it as
the complete solution to our power generation needs for the coming centuries.
Thousands of times more power than we're consuming is falling from the sky;
it has been for eons and will be so for eons to come.  Right now it's just
heating up sand and dirt, but we today have the technology to convert just
a 60 mile square patch of that into enough electricity to power the entire
US, or a 150 mile square patch to power the entire world's electricity.
Photovoltaics are solid-state, no moving parts, and convert light energy
directly to electricity without putting stone-age steps like boiling water
in the middle of it.  This is a technical slam-dunk.

--grg