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Energy Storage Efficiency Compared to Scalability Volume

05/04/2017 11:09 AM

We are mostly all aware of the high charge efficiency of Li+ ion batteries, 99% or thereabouts. That seems pretty hard to beat.

It is only when you start looking at the costs of scalability compared with other known or proposed energy storage schemes, does the real world comparison kick in.

For example:

Tech A: 99% stored eff.; Cost factor: 10; Specific Energy 0.2 Kwh/Kg; Volumetric Energy: 0.7 KWh/L

Tech B: ~37% (based on BAT); Cost factor: 1; Specific Energy 12.9 KWh/Kg; Volumetric Energy: 9.5 KWh/L

Tech C: ~72% net efficiency; Cost factor: ~1-1.5; Specific Energy: 1.41 KWh/Kg, alt. ; Volumetric Energy: 1.46 KWh/L.

The three technologies can be readily compared based on energy storage factors to hand: Q() = Cost Factor / Volumetric Energy Factor / Efficiency.

Q(A): 14.430 - Lithium Ion Battery large scale bank

Q(B): 0.284 - Large gasoline storage tank with jet engine

Q(C): 1.426 - Molten Silicon (once the TPV energy coupling is worked out)

Gasoline is still (and probably always will be) the clear winner simply due to its immense volumetric energy density, reasonable efficiency (although lowest of the three), and cheap cost.

With more and more pathways to gasoline presenting themselves now and into the future, and with its transportability, you almost need "fusion pellets" to beat it.

Even if gasoline does not come from fossil deposits of oil and gas in the future, we already have other pathways to gasoline from renewable energy, and other abundant molecules, or coal (until coal runs out).

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Guru

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#1

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 12:00 PM

Thessse ssseem barely related examplessss. Perhapssss too different for ussseful comparissson.

You have a large battery bank pressssumably charged by the grid.

You have jet engine with a large fuel tank...perhapsssss for backup power or maybe on a large airplane.

You have a molten sssssilicon ssssstorage device, pressssssumably sssssolar heated.

The efficienciessss you compare are each different..charging, net and (basssssed on BAT).

.

These sssseem unlikely to be interchangeable optionssss in almost any practical sssssituation.

.

Jusssst doing my sssnakely besssst to ssssslither in and ssssend thisss thread sssssidewayssss.

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Guru

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#4
In reply to #1

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 12:19 PM

Why not? and knock it off with slithering sss's please, I gives me a heel ache.

gasoline is a perfectly useful energy storage medium.

a Li+ ion battery is also useful energy storage device (in its own milieu)

So is a honking big vat of molten silicon, with TPV's pulling off photons in their selected bands of the spectrum, and directly generating electricity. Makes one wish they could tame their own personal volcano.

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#2

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 12:05 PM

Gasoline and most any of the various liquid fuels will likely dominate the higher powered mobile applications markets for a very long time.

The closest realistic adaptations I can see are going to more of the bio based fuel sources (alcohol, biodiesel and biogasoline) and more low pressure liquefiable gases that are naturally clean burning like propane, butane and their other various hydrocarbon cousins(LPG family) that hold high BTU per unit of volume/mass.

It wouldn't bother me one bit to see a whole new generation of LPG fueled vehicles hit the road being the tech is well developed plus compared to the present emissions compliant engine design costs a simple high efficiency LPG fueled engine is simpler and thus far cheaper to manufacture.

Also given our LPG distribution network is very well established it's not a major step to make it more drive up and pump yourself accessible to the common person at most any local fuel station being most already have a system on site for filling small bottles and cylinders.

So until someone comes up with a stable durable battery that holds 10x the energy per equivalent volume and mass of the present lithium batteries but can be made for 1/10 the cost while still being robust and safe to use liquid fuels will be around for a long time no matter what their base molecular stocks are made/came from.

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#3

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 12:15 PM

"Business as usual" is not a growth strategy.

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#5
In reply to #3

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 12:21 PM

Sometimes, the only thing that ends up growing is the hole being dug.

Holes are best viewed from a slight distance back from the rim, outside the hole.

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#6

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 1:13 PM

No I think nuclear energy beats them all....and would be the most widely used if the technology was allowed to progress...but you can't discard the cost per mmbtu...

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#7
In reply to #6

Re: Energy Storage Efficiency compared to scalability volume

05/04/2017 2:02 PM

Yes, the efficiency is kinda low, the cost factor is astronomical, but the specific energy is way out there astronomical.

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#8

Re: Energy Storage Efficiency Compared to Scalability Volume

05/08/2017 11:59 AM

Why not diesel? Higher energy density and less refining than gasoline.

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#9

Re: Energy Storage Efficiency Compared to Scalability Volume

05/08/2017 4:41 PM

Closed loop, off-river, pumped storage. E. g.,

http://absarokaenergy.com/projects/gordon-butte-pumped-storage/

And, then, with only evaporation and some seepage in lagoon pairs to deplete water, there are the wind farms out in the mountains, etc. with the topo and the land and the water (remember, closed loop) and the existing electrical infrastructure burning excess energy on windy nights, crying out for some way to arbitrage what is blowing in the wind.

How does the kwh/kg work out in such a scenario for a delta H of about 50 m? About one-third of the wind farms between MX and Canada in the plains 0-200 km east of the Front Range have delta H of at least 30 m along internal escarpments.

With clever eco-design, and we might be able to throw in some duck hunting and fishing for ma and pa to sweeten the deal.

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#10
In reply to #9

Re: Energy Storage Efficiency Compared to Scalability Volume

05/08/2017 4:55 PM

That idea has some merit, and I have done calculations on it, but it takes a lot of acre-feet to amount to much. Another concept is the gravel on coal conveyor system lift with hoppers at top and bottom, but it takes one helluva lot of these in parallel over a long strip of escarpment to pay out in big MWh up to GWh storage. I cannot imagine the noise profile, and the environmental footprint (dust, etc.) from one of these being approved even now in the USA.

Then the deal becomes: (1) where is the water going to come from for such a device? Muncipal wastewater (treated effluent to meet waterways EPA criteria) for one... At least that is pseudo-available near the large metro centers. Then there is purchase from river water rights holders. Pumped seawater is probably out of the question, although that could be purified at the sea level, pipeline to the area of interest, and purchased by the municipalities (if the cost was not too astronomical).

(2) how many gigatons of gravel are available, or better, round concrete balls about the size of bowling balls?

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#12
In reply to #10

Re: Energy Storage Efficiency Compared to Scalability Volume

05/09/2017 9:22 AM

Years ago (2012) I rather arbitrarily selected a Texas wind farm from the list of about 30 in operation at the time (Barton Chapel, Jack County). At the toe of the scarp was standing water in Google Earth. The local unit of TXDOT confirmed surface soils in the area generally suited to roadway embankments at about $10 per cubic meter for all costs except land. The upper and lower lagoons were at near edges less than 500 meters apart.

Other than the losses due to evaporation, charging (filling) from on-site wells puts any seepage into recycle to the well aquifer. Further investigation revealed an average lift from various plains aquifers to be about 100 meters. Assuming 50 pumping/generation cycles before the equivalent of full lagoon refill is necessary, the efficiency penalty works out to be 3-4 per cent, still in the 70 percent round trip efficiency range for pumped storage. Net annual evaporation for bare water surface is about 1.5 meters.

At some point the wind folks and the hydro folks will start talking and a PhD dissertation, including operational algorithms, feasibility and environmental impacts will emerge. Beyond mom and pop hunting, fishing, etc. the lagoons become opportunities for floating PV arrays (Ciel et Terre - http://www.ciel-et-terre.net/) or aquaponics. Gordon Butte is today's lowest hanging fruit dedicated pumped hydro, largely due to a major delta H, but, not being in a wind farm, still quite a bit of electrical infrastructure to be built beyond the pure hydro components.

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#13
In reply to #12

Re: Energy Storage Efficiency Compared to Scalability Volume

05/09/2017 11:07 AM

Thankfully this does not (yet) involve any taxpayer money. While I agree that pumped storage is a useful adjunct to load balancing (I'm sitting about 80 miles from one that I'm familiar with), it will be interesting to see if this particular project ever gets to be built with only private money.

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#14
In reply to #13

Re: Energy Storage Efficiency Compared to Scalability Volume

05/09/2017 11:13 AM

I can echo that sentiment. We still have not totally solved the "spinning reserve" issue in some markets, however. Basically, in West Texas, when the wind dies down on a really hot day, if you are in the power business, you better have some fast start units.

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#11
In reply to #9

Re: Energy Storage Efficiency Compared to Scalability Volume

05/09/2017 8:56 AM

According to my handy dandy calcumalator, 50 m head gives you this:

E=mgh, and ρ = ~1000 Kg/m3, and g = 9.80665 m/s2, and h = 50 m

E(per m3) = 1000 x 9.80655 x 50 = 490.3325 kJ, or 0.136203 kWh

so E (per L) = 0.4903325 J , or 1.36203x10-4 kWh. (energy per Kg lifted 50 m).

E(per acre-ft) = 490.3325 kJ x 1233.48183755 m3/acre-ft = 604,816.233 kJ

This represents 168.0017 kWh (0.1680 MWh), so if your storage can be quite deep, energy integrates up faster toward the end of the pumped storage cycle (takes more energy to pump into the reservoir the deeper it gets), and you need a lot more than one acre storage to realize much load during peak demand. I estimate the smallest economical reservoir to be at least 2-3 square miles. Also, many areas near the "cap-rock" in Texas, the drop-off is a whole lot more than a mere 50 m. Near Palo Duro Canyon, the drop-off is estimated to be a maximum known 800 ft.(243.8 m). That reduces the size of storage at top (and bottom) to a much more workable value, although don't count of using that canyon any time soon. It is a Texas State Park.

https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/

Now you can "roll your own", cowboy.

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#15
In reply to #11

Re: Energy Storage Efficiency Compared to Scalability Volume

05/09/2017 11:36 AM

Thanks. I pulled up my Mathcad from 2012. It looks like we may be separated in numbers by a factor of 3 or 4 for the size of each lagoon.

In summary, for a lagoon pair with 30 m net operating head at a 24 hour generating capacity of one-quarter that of the wind farm (120 MW) at full steam over 24 hours (2,880,000 kwhr), I find lagoon surface areas of 1.5 square km, each, at an 8 m average operating range within a 10 m average height berm, will provide the hydrostatic potential, with the round trip and well pumpage efficiencies factored in. Stabilized berm with a stilling basin at each lagoon works out to about 2 million cubic meters of dirt for a construction cost of $20 million per lagoon berm, plus about $40 million for the hydro/electrical lashup, driving the hydro project to $100 million for 30 MW of storage capacity, marginally less than the unit capacity cost of the wind system itself.

It ain't cheap, but it is all bread and butter now stuff.

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#16
In reply to #15

Re: Energy Storage Efficiency Compared to Scalability Volume

05/09/2017 12:11 PM

I did not factor in the additional energy accumulated by the continually raising head height as more and more water is added, only the initial boundary number.

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