The latest developments in energy storage technology

[russ_watters]

It is certainly true that neighbors are not allowed to casually pool together to make a micro grid. For example running an extension cord to the next door neighbor. I think that's what you meant.

No, it isn't what I meant: most individual houses that have their own panels cannot use them if the normal commercial grid goes down.

But lots of people live off the grid permanently, and legally.

I'm not sure what qualifies as "lots", but certainly the vast majority of people with solar panels are connected to the grid. And there at least used to be some municipalities with backwards codes that wouldn't recognize the solar array and would not allow permanently disconnecting from the local power co.

Also, people with their own power generation can and do legally connect to the grid via an approved interface device which include a transfer switch to assure that you won't backfeed the grid. In other words, they stay disconnected, from the outside world.

Some, yes, but most do not have equipment for that and cannot use their solar panels in a blackout.

 

[russ_watters]

hmm, cubic meter (volume)? they're using 12kg (weight) LPG gas bottles here

By "LPG" do you really mean propane or liquefied petroleum gas?

http://www.elgas.com.au/blog/350-propane-lpg-whats-what

 

[Trainee Engineering]

By "LPG" do you really mean propane or liquefied petroleum gas?

http://www.elgas.com.au/blog/350-propane-lpg-whats-what

according to the source, the main components are propane (C3H8) and butane (C4H10)

 

[anorlunda]

No, it isn't what I meant: most individual houses that have their own panels cannot use them if the normal commercial grid goes down.

I'm not sure what qualifies as "lots", but certainly the vast majority of people with solar panels are connected to the grid. And there at least used to be some municipalities with backwards codes that wouldn't recognize the solar array and would not allow permanently disconnecting from the local power co.

Some, yes, but most do not have equipment for that and cannot use their solar panels in a blackout.

Those are pretty extraordinary claims Russ. The backup power industry and the residential solar power industry would be very surprised to hear that.

I'm going to have to call for your source. Name one verifiable municipal ordinance or code anywhere that says what you claim.

I think that you will find the opposite. Residential solar (or generator, battery, wind, or hydro) grid connection equipment are not forbidden to disconnect from the grid in a blackout, they are mandated to do so. You say that most solar owners are grid connected but do not have that grid interface equipment. I say that they are mandated to have it for grid safety reasons.

 

[Rive]

Those are pretty extraordinary claims Russ.

Not really. It's just not told with the right terms.

To spare on the local storage costs most household PV installations are feeding their power back to the grid daytime.
Due grid safety reasons the local DC-AC converters required to shut down in case the grid is down.
To enforce this kind of shut down the type of inverters which are allowed to be connected is usually limited to specific types.

So: general household PV installations won't be usable during blackout, since they shut down themselves.Backup power is a different business, with its own ways.
Due safety reasons local grids with backup should be built with easily recognizable, separate way than the 'normal' grid. So one will know that they won't be down during a power outage.

Now, what the OP suggested is a 'backup', so: a local grid which does not shut down, but with PV feed-in. However, since it's also a PV installation, with the common equipment it'll try to feeding back to the grid, so it's required to shut down during outage.
This way, it's a complete mess.

To the OP: give up with solar, and you will find plenty of equipment for this. Or go with solar and prepare for the eternal suffer...

 

[mheslep]

Some, yes, but most do not have equipment for that and cannot use their solar panels in a blackout.

Not sure what you mean here. As you know, any generator wired into the house utility panel must have a transfer switch, i.e. one or the other powers the residence so the generator can't throw power onto the grid.

I don't know, but I would think a home solar array connected to the grid, and almost all of them are, must have some kind of equivalent mechanism in the event of a blackout to block a backfeed to grid, creating havoc. Most likely this occurs via the inverter sync to the line. No line detected and the inverter opens the solar circuit. Its also feasible to have a double throw switch, so that when the line frequency drops the inverter runs free connected to the house load. I don't know if that's practical.

 

[russ_watters]

I think that you will find the opposite. Residential solar (or generator, battery, wind, or hydro) grid connection equipment are not forbidden to disconnect from the grid in a blackout, they are mandated to do so. You say that most solar owners are grid connected but do not have that grid interface equipment. I say that they are mandated to have it for grid safety reasons.

Somehow it seems we are talking past each other. I know that most solar systems are grid connected and have equipment to manage the direction of flow of electricity.

What I am talking about is just what happens when the grid experiences a blackout. What happens most of the time is that the solar array's inverter shuts off and the array is no longer providing power to the house or grid; and specifically the house is without power. I don't know the nuts and bolts of how it shuts off; what/where it disconnects, all I am saying is that you cannot use most solar systems for backup power (in the event of a grid blackout).

So, conversely, is it your position that during a blackout most residential solar arrays continue powering the house?

 

[russ_watters]

Not sure what you mean here. As you know, any generator wired into the house utility panel must have a transfer switch, i.e. one or the other powers the residence so the generator can't throw power onto the grid.

I don't know, but I would think a home solar array connected to the grid, and almost all of them are, must have some kind of equivalent mechanism in the event of a blackout to block a backfeed to grid, creating havoc. Most likely this occurs via the inverter sync to the line. No line detected and the inverter opens the solar circuit. Its also feasible to have a double throw switch, so that when the line frequency drops the inverter runs free connected to the house load. I don't know if that's practical.

I'm not sure about the actual nuts and bolts, but the problem I see is that because the solar array provides intermittent power you can't use it in a blackout at all without a battery backup/UPS - which most residential arrays don't have. And the system would need to balance the load between 3 sources of power instead of 2 and the control circuit has to be on the UPS; a different/more difficult control problem.

 

[Nidum]

@ Trainee Engineer - Is there any way that you can use the flood water or fallen tree wood to generate power ?

 

[russ_watters]

Those are pretty extraordinary claims Russ. The backup power industry and the residential solar power industry would be very surprised to hear that.

I'm going to have to call for your source. Name one verifiable municipal ordinance or code anywhere that says what you claim.

Not meaning to punt on this, but I'm still not certain you are asking me the right question. However, here is a solar integrator that says none of their arrays work during a blackout, for the reasons I have stated:

https://www.solarenergyworld.com/faqs/power-goes-will-solar-system-keep-making-energy/

Many people considering going solar ask if a solar system works during a power outage. If you have a solar battery system as well as a solar PV system, your power will continue to work. However, since your system is grid-tied, for safety reasons, if there is a power outage your solar system will automatically shut off when the power goes out. Solar batteries can add as much as 30% to the cost of a solar system presently, so most homeowners do not go with this option.

Should you wait to go solar until battery back-up is less expensive? Why wait? You can start saving money right now, without battery backup. None of Solar Energy World’s 2000+ Maryland customers have solar battery back-up...

 

[Dan8420]

Hey guys, first post here. On the topic of energy storage though, what're your thoughts on the Vanadium Redox Flow Batteries? From what I am reading they have a long life span compared to other batteries. I realize energy density is low so large installations are necessary for any sort of 'whole home backup' or micro grid backups. However, the life span could help offset that I believe. Thoughts?

Here is a couple articles I have been browsing, can provide more if requested.

https://energy.gov/sites/prod/files/VRB.pdf

https://en.wikipedia.org/wiki/Vanadium_redox_battery

 

[anorlunda]

Not meaning to punt on this, but I'm still not certain you are asking me the right question. However, here is a solar integrator that says none of their arrays work during a blackout, for the reasons I have stated:

I did some research myself Russ. You are correct. My apologies.

A transfer switch allows backup power during blackouts, but most solar DC/AC inverters-grid interfaces do not include the transfer switch. Add-on transfer switches are also difficult to make work. You need a grid-interface with an integrated transfer switch, which is not the cheapest.

 

[Trainee Engineering]

@ Trainee Engineer - Is there any way that you can use the flood water or fallen tree wood to generate power ?

not sure how to do that, can you explain more?

 

[sophiecentaur]

not sure how to do that, can you explain more?

The water / logs idea is really a separate matter. The railway could perhaps carry logs downhill but they would need to be brought to the rail head and loaded. The chemical energy available in a log is far greater than its gravitational potential energy and then there's the cost of (low efficiency) collecting and loading.
If there's enough rainwater, why not use a straightforward hydro system in parallel? The use of water and logs as a downhill load is not attractive because they have relatively low density.

 

[Nidum]

I meant hydro system for electrical power generation and fallen tree wood as fuel for direct heating and for engine based electrical power generation .

 

[Nidum]

Feasibility of hydro power depends on nature of flooding . Running water is needed for simple generation schemes .

A wood charged gassifier is quite easy to make . Yields charcoal and fuel gas .

A steam engine based system is a bit more difficult but certainly quite feasible .

 

[sophiecentaur]

A wood charged gassifier is quite easy to make . Yields charcoal and fuel gas .

Wood is only good for 'fun' in towns or in country places where it is readily accessible. The American railway system demonstrates the problems with wood. They cut vast swathes through forests until it became uneconomical to gather wood at great distances from the rails. Then they had to move to coal.
Transporting wood to a static "steam based system" is, likewise, not economic under most conditions, these days.

 

[Nidum]

The core question of this thread was about a single user system for providing backup power for domestic use when the local electricity grid system was turned off during flooding .

 

[sophiecentaur]

The core question of this thread was about a single user system for providing backup power for domestic use when the local electricity grid system was turned off during flooding .

More than that, I think. This OP is about storage and the thread has definitely gone that way (rambling, as usual). Scale is a major factor in selecting what's best. The most efficient energy management strategy involves providing all your energy by cheap methods and storing any spare energy. Backup is another question and we are sometimes stuck with having to use inefficient / expensive sources during periods of high demand or failure. Hydro for peak loads could be workable as long as the capital cost (dams are damned expensive) and capacity work. Using wood as an energy source has limitations as discussed earlier- it costs a lot to move it to where you want. Capital cost of a gassing plant would be hard to justify for a private individual - wouldn't it? So would an anaerobic digester. Good for a small community, perhaps.

 

[nsaspook]

I did some research myself Russ. You are correct. My apologies.

A transfer switch allows backup power during blackouts, but most solar DC/AC inverters-grid interfaces do not include the transfer switch. Add-on transfer switches are also difficult to make work. You need a grid-interface with an integrated transfer switch, which is not the cheapest.

There are a few inverters now that allow for limited isolated AC power from a grid-tie system (without battery backup) during a blackout. Without storage it's completely dependent on sun-light but that's better that nothing in an emergency.
http://www.sma-america.com/products...-5000tl-us-6000tl-us-7000tl-us-7700tl-us.html

 

[Trainee Engineering]

so far, I notice that there are 2 methods to address long-duration blackout here:
1. generate the needed power on and use it day by day
2. generate and store the needed power for the entire 3-week period (in my case, it's 21 days @10kWh, totalling 210 kWh) in one go and store this for the whole year

if possible, I prefer method #2. is there any battery out there with such capacity that's cheap and durable (minimum leakage through long period of time).

 

[sophiecentaur]

in one go

You would need to define what that means. As it stands, it implies a massive Power capability which would be unused for most of the year. Not good value. The cost of a very high spec battery would make it less attractive than using a cheaper (lead acid, for instance) system that's charged up with the cheapest source (overall cost = capital plus energy input) you can get hold of and possibly trickle charged from another source until the time it's actually needed.
But a battery bank that's only used once a year is probably not good value. You could not expect many years of use. Otoh, a second hand diesel generator set would not cost a lot and the fuel could be bought over the year (getting it at the cheapest prices) and stored in a tank. It's not a green solution but does that matter for three weeks of the year. A system like that could last you for decades.

 

[anorlunda]

cheap and durable

It would be far more effective to reduce the energy demands during the blackout period from 10kWh to 1kWh per day. At that level, solar+lead-acid batteries, become much more affordable and practical.

If you can eliminate the AC inverter, it becomes more cheap and durable. LED lighting and device recharging are best done with DC. 12VDC refrigeration systems are very energy effective, cheap, and durable. Propane fueled refrigeration systems are another alternative. There are many ways to pump water without use of electricity.

It becomes more of a social problem than a technical problem. You must convince the people to make do with less. If your goal is to provide during blackouts the same convenience, comfort and cost levels as the power grid provides, you'll fail.

Can you list for us how the 10 kWh/day is being used?

 

[mfb]

A storage system for the full three weeks will cost at least a factor 10 more. You said price is not an issue in post 1, but where is the big disadvantage of on-demand production if it saves more than $50,000?

Reducing electricity consumption will help in both cases, of course.

 

[Trainee Engineering]

You would need to define what that means. As it stands, it implies a massive Power capability which would be unused for most of the year. Not good value. The cost of a very high spec battery would make it less attractive than using a cheaper (lead acid, for instance) system that's charged up with the cheapest source (overall cost = capital plus energy input) you can get hold of and possibly trickle charged from another source until the time it's actually needed.
But a battery bank that's only used once a year is probably not good value. You could not expect many years of use. Otoh, a second hand diesel generator set would not cost a lot and the fuel could be bought over the year (getting it at the cheapest prices) and stored in a tank. It's not a green solution but does that matter for three weeks of the year. A system like that could last you for decades.

in one go means I store all the energy (210 kWh) now to be used next year. but in one go may mean I collect the energy in a week, or in a month, no problem. it just means that I don't need to store up energy for a day, and then consume all the next day, and keep repeating that cycle everyday.
btw, when it's flooding, the water doesn't really move. we just wait till it recedes, and the river is quite far away from my residence complex. like this one

It would be far more effective to reduce the energy demands during the blackout period from 10kWh to 1kWh per day. At that level, solar+lead-acid batteries, become much more affordable and practical.

If you can eliminate the AC inverter, it becomes more cheap and durable. LED lighting and device recharging are best done with DC. 12VDC refrigeration systems are very energy effective, cheap, and durable. Propane fueled refrigeration systems are another alternative. There are many ways to pump water without use of electricity.

It becomes more of a social problem than a technical problem. You must convince the people to make do with less. If your goal is to provide during blackouts the same convenience, comfort and cost levels as the power grid provides, you'll fail.

Can you list for us how the 10 kWh/day is being used?

1.5 kWh --> fridge
2 kWh --> AC
2 kWh --> rice cooker, 2 TVs, LED bulbs
1.5 kWh --> PC whole day
3 kWh --> spare, just in case. so basically, 8 kWh should be enough.
ideally, I'd prefer not change any lifestyle, even during blackout, but if it's not possible, then will resort to "graceful degradation", meaning, sacrifice the least needed ones. the listing above is already sorted based on importance, top being most important, bottom least important.

A storage system for the full three weeks will cost at least a factor 10 more. You said price is not an issue in post 1, but where is the big disadvantage of on-demand production if it saves more than $50,000?

Reducing electricity consumption will help in both cases, of course.

I'm not against on-demand production, but as someone said (forgot where exactly in these posts), solar power only brings misery, and my alternative is methane or gasoline generator, which also needs to be refilled everyday, and when it's flooding, not sure if that's going to work

 

[rbelli1]

when it's flooding, not sure if that's going to work

If you don't have a flood safe place to store a generator and three weeks of fuel you will certainly not have a place to store three weeks worth of batteries.

For 8kWh per day for three weeks you need about 250 liters of batteries.
https://en.wikipedia.org/wiki/Lithium-ion_battery

You need only about 60 liters of diesel.
https://en.wikipedia.org/wiki/Diesel_generator

The converter for both systems will be of a similar size magnitude.

Another benefit of a generator is that you will be able to find someone to repair it with little or no trouble. You can learn basic maintenance yourself in a few hours.

Is seems to me if you are willing to spend a large sum of money on a backup system you could go the generator route and outfit your entire apartment complex and provide operating costs for many years with the same amount of money.

BoB

 

[Rive]

so far, I notice that there are 2 methods to address long-duration blackout here:
1. generate the needed power on and use it day by day
2. generate and store the needed power for the entire 3-week period (in my case, it's 21 days @10kWh, totalling 210 kWh) in one go and store this for the whole year

if possible, I prefer method #2. is there any battery out there with such capacity that's cheap and durable (minimum leakage through long period of time).

With stored 200+kWh you will sit on the very top of a veeeeeryyyyy water sensitive bomb. Do you really want that? During a flood?
The grid is down exactly to prevent such situations. But with such scale battery backup, it's worse than it would be with the grid on...

I suggest to build a limited capacity battery backup, which can provide adequate power for limited usage for 1-2 days: and back it up with some generator.
The limited battery backup can be built safely.
The fuel is not that flood sensitive.
The battery alone can handle 90% of the daily load.
The generator can recharge the battery fast.
The battery and the generator together can handle the rest of the load.

This way it is a classic, widely used system: esy to build, handle and repair.

 

[jim hardy]

i grew up in hurricane territory, South Florida. Onsite generators became affordable to average folks only around the 1980's . One learns to get by without central airconditioning , and in S Fla you can get by without hot water because it comes out of the ground seventy something F.
So a couple KW gas generator will do just fine for a fridge and lights.
A Coleman gasoline campstove got us by for two weeks after Andrew (1992) , i had no generator.
After Hurricane Irene friends loaned me a 4 kw generator and i considered it a luxury for it'd start a one room "windowshaker" airconditioner that even drowned out the generator noise so we could sleep comfortably on 90 degF nights. I was without electricity for 3 weeks.
What you miss most is refrigeration. I'd get a propane fridge from a RV place for the garage, and a small generator to keep the freezer cold. Harbor Freight sells a 800 watt two stroke for 88 bucks when on sale.

Back to topic of energy storage

Did anybody watch NOVA this week ? Some guy has solved the pyrotechnics problem with lithium batteries. He uses a permeable plastic between the plates, in the Nova show he drives nails through it with no ill effect.
http://www.pbs.org/wgbh/nova/tech/super-battery.html
old jim

 

[sophiecentaur]

I'd get a propane fridge from a RV place

The Waeco (and others) 12V compressor fridges are 'real' fridges and are very economical on current - averaging only around an Amp. I have a small one (really tiny) that will deep freeze its contents to -18C. It would be worth doing the sums to try to include this in any electrical power budget. Propane has its place, of course, when the electrical supply won't support even that low level of power.

 

[jim hardy]

The Waeco (and others) 12V compressor fridges are 'real' fridges and are very economical on current - averaging only around an Amp. I have a small one (really tiny) that will deep freeze its contents to -18C. It would be worth doing the sums to try to include this in any electrical power budget. Propane has its place, of course, when the electrical supply won't support even that low level of power.

Certainly that's good sensible advice. 12 volt appliances are becoming more available, too.

I think nowadays DIY'ers could add a 12 volt system to their house, a few LED lights in every room and an inverter big enough to carry the fridge via extension cord.
An automobile alternator , lawnmower engine , and "utility battery" like used in riding lawnmowers is the 'poor man's' answer. I plan to do that in my guest house.

I have a gas kitchen stove because electricity can go out. It was sure nice after Hurricane Irene to have hot coffee, i invited neighbors over next morning. Wind was still over 40 mph but we thanked our lucky stars it went west of us.. old jim