# The latest developments in energy storage technology

1. Jan 28, 2017

### Trainee Engineering

Hi all,

I'm interested in the latest development in battery technology. as of now, from what I understand, the most advanced tech in energy storage (battery) is created by Tesla, the PowerWall. but, even that, can only store 14kWh per unit. my house consumption is about 10kWh per day. my question is, what are the type of batteries out there available to the public? I'm only concerned of these things:
1. capacity --> I need to store 2-3 weeks worth of energy (in case of blackouts), so, it's somewhere around 140kWh - 210 kWh. if possible, I need it to be less than 10 units (so each unit is around 21kWh)
2. durability --> must be able to store huge amount of energy for a long period of time without dissipating. Now, it wont be charged and discharging frequently. charged only after a blackout, and wont be discharging until the next blackout, so storing for long time
3. warranty --> if possible, above 10 years warranty that energy leakage is less than 5%

price is not an issue. what are my options?
what's the latest type of battery suited for this type of usage?

thanks

2. Jan 28, 2017

### oz93666

One 14 kWh Powerwall battery $5,500 ... that means you need to spend around$80,000 every ten years ! and there are many loopholes in the 10 year warranty.

There's nothing special in these tesla packs ... just Lithium ion batteries .... someone with moderate technical knowledge could make an equivalent for a quarter of the cost .

You could buy 10kw of solar panels for $5000 ...this would generate on average 30kwHrs /day three times your consumption ... to cover you for cloudy days , and night time consumption a modest sized battery ....the whole setup much less than$10,000...

Li -ion are the best batteries available for what you want (long life compactness) ...lead acid are still the most cost effective.

Last edited: Jan 29, 2017
3. Jan 29, 2017

### Trainee Engineering

ok, when you put it that way...
for solar panel? what's the price per wp now?

4. Jan 29, 2017

### oz93666

Alibaba $0.4 /W or less delivered to a port of your choosing ... Solar industry is a big rip off , companies make a big mark up for re selling these panels and putting them on your roof or land ... I bought 5KW about 4 years ago at$0.5 /W , alibaba ... I had to pick them up at the port , no taxes where I am ... prices have dropped a lot since then ... Philippines government just bought a GW @ $0.2 /W including inverters !!! ... panels are just sand and a bit of silver ...dirt cheap to make .... It depends if you want to do it all yourself , if you do , 10kw with off grid inverter and batteries less than$10K ...

If you get a company to install everything ...no idea ... will depend on country , but if they give you a high price you can tell them the price of panels and inverters on alibaba don't let companies tell you their panels are better quality , they're all the same , the panels will still deliver 75% even after 25 years , inverters, many different types , best to buy good quality one .... Any schoolboy could wire it up for you , ideally put the panels on open land , easier to clean than on a roff.

Last edited: Jan 29, 2017
5. Jan 29, 2017

Staff Emeritus
If you regularly have blackouts lasting weeks, I wouldn't be thinking about an $80,000 storage device. I'd be thinking about a$5000 gas generator.

6. Jan 29, 2017

I found a 700 W generator for less than $150, and 2 kW for less than$1000. An additional battery for peak loads (cooking) and smoothing out the gas generator load should be around $1000. If you want to avoid CO2 emissions, you can buy a gas generator plus a small-scale photovoltaic/battery system that covers most of your electricity consumption but does not have to cover it all. 7. Jan 29, 2017 ### Trainee Engineering interesting, first time hearing about gas generator. so, how much kwH per kg of gas? anybody has experience with these gas generators? or perhaps can point me to some links? I dont mind CO2 emissions since this is not gonna be used frequently, only during blackouts, which usually lasts less than 3 weeks in a year (in total) 8. Jan 29, 2017 ### Trainee Engineering after some researching, both diesel and gas generators will cost more to generate 1 kWh compared to electricity price from the grid (I guess that's to be expected). now, between gas, gasoline and diesel generator, what's the most recommended? my requirements: 1. be able to run in long period of time (24 hours non stop if possible) 2. for household use (around 2kW) 3. not too noisy (residential area) 4. efficiency (most kwH generated per unit of$$resource needed) not too worried about air pollution since I'll be putting the generator on open space on 3rd floor Thanks 9. Jan 29, 2017 ### mfb ### Staff: Mentor ~2 kWh/liter look realistic. A bit more per kilogram as it is lighter than water. At ~$1/liter that makes 50 cents/kWh (more expensive than from the grid - not surprising). 10kWh/day over 3 weeks is 210 kWh, or ~$100 in fuel costs for a single 3-week blackout. If you combine a 2 kW generator with a small battery, you can run it at 50% load for 10 hours a day - during the night the battery is sufficient to power the fridge and so on. Just for longer blackouts, the gas generator is probably the cheapest option. Photovoltaics would also deliver energy the rest of the year, of course, that should be taken into account. 10. Jan 29, 2017 ### Vanadium 50 Staff Emeritus Of course. But like you say, it's 3 weeks out of the year. And during those 3 weeks you don't have a grid option. You need to think about the load, and the source of fuel. If you have natural gas to your house already, and if it is still delivered during blackouts. that's a much simpler option than storing fuel. 11. Jan 29, 2017 ### mheslep Without subsidies, all alternatives cost more than grid power in the mainland US. 12. Jan 29, 2017 ### mheslep Installation (connection to the home electrical service box with a switchover) and a natural gas utility connection is at least$1500.

13. Jan 29, 2017

### rbelli1

One of the new quiet Honda inverter units is a good option as they are surprisingly (shockingly?) quiet. They are pricey but worth the money. There are less expensive (by about half) alternatives with equivalent specs but I have no experience or other knowledge about them.

Is that for an auto-switch-over or manual?

BoB

14. Jan 30, 2017

### mheslep

Auto. I think the equipment (transfer switch) cost is relatively inexpensive compared to the labor. Most of the cost is labor, i.e. licensed electrician.

15. Jan 30, 2017

### sophiecentaur

There's the rub. In the UK the regs are very tight and you need to be part of 'the system' and be part of the feed in tariff arrangement. The approved installers charge a fortune and the government incentives for green energy are reducing.
Any alternative approach to a 230V standby supply in UK homes is really not on the cards, I reckon.

16. Jan 30, 2017

### Staff: Mentor

Three weeks of grid outage per year in the UK? I doubt that. We are probably talking about a developing country.

17. Jan 30, 2017

### mheslep

Or, six weeks of half power from a solar array cloaked in a UK would require the three weeks of battery backup.

18. Jan 31, 2017

### CWatters

https://blogs.scientificamerican.co...me-can-increase-energy-consumption-emissions/

It seems to be suggesting that if you send excess solar PV to the grid then all of the electricity generated is used to reducing C02 emissions. Whereas if you store it in a battery and use it yourself later then some is lost in the charging efficiency. So overall it's greener NOT to use a solar PV backup battery.

19. Jan 31, 2017

### Staff: Mentor

Depends on where you are. As an example, on a very sunny day in Germany photovoltaics produces so much that there are no additional CO2 savings - no fossil fuel power plant gets shut down if you dump even more power from photovoltaics into the grid.

20. Jan 31, 2017

### Staff: Mentor

Sure, but that is a different question than what you were asking in the OP. In the OP you asked about emergency energy storage, not full time grid replacement (which would be illegal with a generator and only semi-legal with solar...and, by the way, solar is generally illegal to use for emergency power).

The comparison of a generator to battery backup is a no-brainer: your requirement is for about 30 gallons of gas, costing about $80 (or$800 over 10 years if you use it once a year) versus a battery pack costing \$80,000.

Another option is natural gas/methane if you have a connection to that already. It is much cheaper than gasoline (roughly 1/3 the cost) and is not subject to outages like electricity is -- it would pretty much only go down during a zombie apocalypse or giant meteor impact.

Last edited: Jan 31, 2017