Why energy storage sucks • Hacker News Board

Re: Why energy storage sucks

#21

Post by stcredzero » Thu, Mar 03, 2016, 12:24 PM UTC

davedx wrote: post #3

I really want to read this article, but there are too many spelling and grammar mistakes or lack of punctuation. Please consider spellchecking it?

Spellchecking? What about innumeracy?

As you can see if you only drain your battery to 75% (meaning you only use 20% of your capacity) you get tremendously more cycle’s (more than double!) then say using 50%. So when systems are designed for energy storage you generally want your batteries to last a long time (since they’re expensive) so you want the maximum amount of cycles for them, which means that you should only discharge them 80%. As you can see this is getting quite frustrating, as now simply to power you’re off-grid system at night you need to purchase 80% more battery capacity than you actually need.

75 + 20 = 95. Okay, close enough to 100. But discharging to only 20% means you need to buy 500% the capacity, not 180%!

Re: Why energy storage sucks

#22

Post by masklinn » Thu, Mar 03, 2016, 12:25 PM UTC

Faaak wrote: post #14

Energy storage not only consists of batteries… Pumped hydro, for example, works well and does not decays over time.

Pumped hydro is absolutely great, but it's an option for tremendous (grid-level) scales, and requires convenient locations (e.g. a hilltop you can "blow up" with a large stream nearby, or a standard dam with a lake or lake-able location close to its foot). It's way, way beyond the scales the article is talking about (note the picture from a health clinic in Rwanda).

Re: Why energy storage sucks

#23

Post by masklinn » Thu, Mar 03, 2016, 12:27 PM UTC

pjc50 wrote: post #7

DiabloD3 wrote: post #4

So what happened to the idea of using some modern version of flywheels to store power?

They were deployed in Formula 1: https://en.wikipedia.org/wiki/Kinetic_energy_recovery_system I'm not aware of any building or utility-scale systems.

Fresno City has approved an Amber Kinetics project for flywheel-based large-scale solar storage: http://kvpr.org/post/fresno-project-store-solar-electricity-...

The company advertises 160kWh/TEU (as 40ft container units): http://amberkinetics.com/products/

Re: Why energy storage sucks

#24

Post by cplease » Thu, Mar 03, 2016, 12:29 PM UTC

paulsutter wrote: post #20

Pumped hydro is much cheaper than batteries per KW (max storage rate) and KWh (storage capacity) is limited only by reservoir size. The roundtrip efficiency is about 80% and it's able to store for months at a time. Heindl Energy in Germany is developing hydraulic storage, which can work even on flat ground (basically, raising a rock formation with pumped water). They've designed capacities up to 120GWh: http://www.he…

Of course. Despite the title the article is only about off-grid storage, basically batteries. Though even off-grid storage can be on-grid if it's sometimes connected, as some plans for the future of plug-in hybrids call foresee.

Sadly you cannot very well use a miniature hydroelectric dam for off-grid energy storage on-board an electric car or electronic mobile device.

Re: Why energy storage sucks

#25

Post by brillenfux » Thu, Mar 03, 2016, 12:29 PM UTC

Faaak wrote: post #14

Energy storage not only consists of batteries… Pumped hydro, for example, works well and does not decays over time.

Plus you probably cannot beat the cost efficiency. I see challenges for mobile applications, though.

Re: Why energy storage sucks

#26

Post by wglb » Thu, Mar 03, 2016, 12:29 PM UTC

masklinn wrote: post #12

hannob wrote: post #10

Earlier quoted context omitted.

Flywheels target a bit of a different problem than many other energy storage solutions. They are only able to store energy for very short periods. This is valuable to counter short term changes in the power generation, but it won't help you to store solar power for longer dark periods. Wikipedia has some info about existing installations: https://en.wikipedia.org/wiki/Flywheel_storage_power_system tl;dr Only a few of…

> They are only able to store energy for very short periods. Your own link quotes self-discharge rates of 5%/day (for high-vacuum wheels I assume), that's more than sufficient for daily solar storage.

I would consider that to be short-term storage. Long Dark periods could be weeks.

Re: Why energy storage sucks

#27

Post by masklinn » Thu, Mar 03, 2016, 12:32 PM UTC

wglb wrote: post #26

masklinn wrote: post #12

Earlier quoted context omitted.

> They are only able to store energy for very short periods. Your own link quotes self-discharge rates of 5%/day (for high-vacuum wheels I assume), that's more than sufficient for daily solar storage.

I would consider that to be short-term storage. Long Dark periods could be weeks.

"Short term changes in power generation" are not day-scale, what you consider to be short-term storage has very little to do with the comment I replied to, or with the original article.

Re: Why energy storage sucks

#28

Post by mangecoeur » Thu, Mar 03, 2016, 12:32 PM UTC

Very limited view of energy storage tech frankly. Quick list of things I am aware of (some deployed and some in labs)

- Pumped hydro, by far the most widespread

- Flywheel storage, used at grid scales for frequency regulation

- Thermal storage used in conjunction with solar power using various materials - molten salt, HTF, hot dry rock

- Many different battery chemistries:

    - High temperature batteries (e.g. ZEBRA batteries specifically developed for cost effective grid scale storages https://en.wikipedia.org/wiki/Sodium%E2%80%93sulfur_battery)

    - Sodium-ion batteries

    - Metal hydride batteries

    - Redox flow batteries such as zinc-air systems

- Compressed air storage

- Phase change storage, including hybrid compressed/liquefied air storage

- Seasonal thermal storage https://en.wikipedia.org/wiki/Seasonal_thermal_energy_storag...

- Water electrolysis + hydrogen fuel cell cycle

Probably missed a bunch too. All to say there are a lot more solutions then lead-acids and lithium batteries- although in fairness those are the most accessible options in small scale systems

Re: Why energy storage sucks

#29

Post by bloat » Thu, Mar 03, 2016, 12:37 PM UTC

masklinn wrote: post #22

Faaak wrote: post #14

Energy storage not only consists of batteries… Pumped hydro, for example, works well and does not decays over time.

Pumped hydro is absolutely great, but it's an option for tremendous (grid-level) scales, and requires convenient locations (e.g. a hilltop you can "blow up" with a large stream nearby, or a standard dam with a lake or lake-able location close to its foot). It's way, way beyond the scales the article is talking about (note the picture from a health clinic in Rwanda).

How big of a tank on your roof do you need to replace a box of lead acid batteries?

Re: Why energy storage sucks

#30

Post by aswanson » Thu, Mar 03, 2016, 12:40 PM UTC

stcredzero wrote: post #21

davedx wrote: post #3

I really want to read this article, but there are too many spelling and grammar mistakes or lack of punctuation. Please consider spellchecking it?

Spellchecking? What about innumeracy? As you can see if you only drain your battery to 75% (meaning you only use 20% of your capacity) you get tremendously more cycle’s (more than double!) then say using 50%. So when systems are designed for energy storage you generally want your batteries to last a long time (since they’re expensive) so you want the maximum amount of cycles for them, which means that you should only…

Yeah, I was hesitant to click on the article based on the title. Thanks for confirming my suspicions.