Nickel-Iron 'Edison' Batteries

Has anyone mentioned using Ni-Fe (nickel-iron, AKA "Edison" - even though he stole the idea) batteries instead of lead-acid?
Plusses:

No toxic lead. No surfuric acid (ouch).

Just iron anode and nickel cathode (unless I have that backwards), and potassium hydroxide or lithium hydroxide for the electrolyte.

Battery lasts for 50-100 years. Yeah. Can be completely drained and recharged (or overcharged) with no ill efects, unlike sulfation in lead-acid batteries.

A person could make it themselves (and many have), see here.

They can be used as a hydrogen generator when recharging

If you trust wikipedia: more info
Also, there is a tiny mention here
Didn't find much else on permies about it.

There are of course downsides to Ni-Fe.

Cost. If you buy them commercially they are way expensive. Part of this, I think, is demand. Not many manufacturers (only 1 in US, I think). Some in Russia and China.

They also usually don't hold as much energy as lead-acid.

But for the benefits, it seems to me it fits well into the ideals of permaculture. Thoughts?
Mod: Should we move this to another thread?

Hey Cam,

The Iron Edison batteries do look like great performers, but don't be lulled into thinking that a strong alkali is any better than a strong acid. In fact, some solar pro's are worried that the electrolyte could even be worse, since all you need to clean up a battery acid splash is baking soda. There are concerns that getting the alkaline solution in your eyes, for example, might be worse that hydrochloric acid.

The incredible long life is absolutely spot-on, though, and I agree that if there was greater demand, and more manufacturers, the price would be a lot more reasonable.

Clear skies,

Brad Vietje
Newbury, VT

I've been living with a bank of NiFe batteries for over a year now. I love them and won't be going back. They are incredibly robust and forgiving. I don't think they would be the best for the solar cart application just too big and heavy. They would work great in a WOFATI or one of the other permanent structures.

Diego from Permaculture Voices had a podcast about those type of batteries a while back.

It was quite interesting.

Nickle-Iron Batteries Podcast

Brad Vietje wrote:... don't be lulled into thinking that a strong alkali is any better than a strong acid. In fact, some solar pro's are worried that the electrolyte could even be worse, since all you need to clean up a battery acid splash is baking soda. There are concerns that getting the alkaline solution in your eyes, for example, might be worse that hydrochloric acid.

Oh, I'm not. We make soap the old way, so I know to be very careful around lye.
Really, I was thinking a person could make everything themselves if necessary, including the electrolyte.
But you're totally right. Strong base can be as bad (or worse) as strong acid.

Dave Redvalley wrote:I've been living with a bank of NiFe batteries for over a year now. I love them and won't be going back.

How did you find the price? Very high but worth it, or just moderately high? Where did you get them from? Was the energy density enough for your application?

Fabrizia Annunziata wrote:Diego from Permaculture Voices had a podcast about those type of batteries a while back.

Thanks for the link. I thought I had heard every podcast, but I missed this one somehow.

The initial price was pretty high, but considering the potential longevity of the batteries it works out to be significantly cheaper than purchasing a good set of lead acid cells. I got mine from ZappWorks there in MT. So far they have worked really well for us. I would like to add another 1kw of solar, but really these batteries will take whatever you feed them and give back plenty. I have my 24v bank set to cycle from 32v down to 18v. These things take the abuse and keep coming back for more. I replaced a 1400 amp lead acid bank with a 500 amp NiFe and we are using our genset about a quarter as much as the previous owners and our family is 3 times the size. Like I said I'll not be going back to lead batteries, this seems to be a perfect application for the NiFe technology.

Dave Redvalley wrote:...I have my 24v bank set to cycle from 32v down to 18v. These things take the abuse and keep coming back for more. I replaced a 1400 amp lead acid bank with a 500 amp NiFe and we are using our genset about a quarter as much as the previous owners and our family is 3 times the size. Like I said I'll not be going back to lead batteries, this seems to be a perfect application for the NiFe technology.

Whoa! I though they were good, but not that awesome!
So let me do the math: ~3 times smaller bank x 4 times less generator use x 3 times bigger family = 36 times better! LOL, though I know you can't really do the math like that.
It is good to hear from someone actually using them, that they are really good batteries.
Seems like the ability to cycle the voltage more widely than lead-acid without damage is a big plus. I will definitely be looking at these when I get a chance to stop paying the leeches for power every month.
Question: Why did you go 24V versus 12V or 48V? Availability/cost of panels/inverters in proper voltage or cable? Or something else? Thanks, Dave!

I've got 330Ah 24V NiFe battery bank (10 pcs 2.4V cells connected in series) on off-grid cottage for the last 20 years, charged up by couple of solar panels while sun is shining and diesel generator as a backup for winter months. They can take serious charge discharge cycling, heat, cold.. The only service needed is to keep the water topped up, as it evaporates slowly when idle and very fast if battery is overcharged. I got the battery bank with 50€ after it had been replaced from a locomotive diesel motor starter battery after appx. 30 years of faultless service (timed service interval for proactive maintenance), expect them to perform still into the far future (now they are like 50 years from manufacture with no noticeable loss in their performance). No way for me to have or recommend any other battery type in a off-grid solar application!

The biggest difference is the depth of discharge (DoD) that you can achieve with these batteries. Lead acid batteries should really only be discharged to 80% max, while the NiFe's can routinely be drawn down to 20% with no damage, thus the 3 times smaller battery bank, with better performance. I do like that math by the way, I see now problem with it at all! LOL. The only reason I have a 24v system vs. 48 or 12 is that is what it was when we bought the place. I would rather spend the money on the batteries than on replacing all of the inverters and switching gear. The 24v seems to be working good for us.

Markku Salmela wrote:I got the battery bank with 50€ after it had been replaced from a locomotive diesel motor starter battery

Markku, what country are you in (I assume Europe)? Is this type of battery common in all diesel locomotives? I'd want to hunt one down...


About discharge of lead acid batteries, "traction" batteries can be discharged way down without as much of an effect on the life. I bought some Trojan 27TMX for my electric fence chargers, and now I can't find it, but at the time I was comparing batteries I was able to find information on depth of discharge vs. life expectancy, and somewhere I even have notes about this, but I decided on the 27TMX because I should be able to discharge it to 50% with the fence charger and get 10 years of life out of it, and only need to charge it every two weeks (for dead-of-winter over cast days when the solar panel doesn't provide anything, never needing charging in the summer).

For lead-acid batteries, if it doesn't have in the documentation either some chart or at least table showing life expectancy at different depths of discharge then it isn't worth buying.

The 80% rule, AFAIK, is more for automotive batteries, which is why they suck for electric fence (unless you have a supply of free car batteries that no longer start cars, and then you can extend their useful life another 6 months or so...).

Andrew Ray wrote:...I was able to find information on depth of discharge vs. life expectancy, and somewhere I even have notes about this, but I decided on the 27TMX because I should be able to discharge it to 50% with the fence charger and get 10 years of life out of it, and only need to charge it every two weeks (for dead-of-winter over cast days when the solar panel doesn't provide anything, never needing charging in the summer).

For lead-acid batteries, if it doesn't have in the documentation either some chart or at least table showing life expectancy at different depths of discharge then it isn't worth buying.

The 80% rule, AFAIK, is more for automotive batteries, which is why they suck for electric fence (unless you have a supply of free car batteries that no longer start cars, and then you can extend their useful life another 6 months or so...).

Yeah, if you're stuck with lead-acid, get the better (more expensive) batteries.
Depth of discharge is one reason why Ni-Fe batteries are so awesome. You can overcharge, then drain them completely, and do it repeatedly, and it doesn't have much effect on battery life.
Try that with a lead-acid and you'll have a dead battery in no time. Just have to keep acid on hand to neutralize the base. (vinegar?)

AFAIK, vinegar should work. Suffice it to say the best protection for eyes are goggles, and worthwhile. My 7th grade science teacher, seeing that my passion for pyromania couldn't be dissuaded said, "Andrew, at least always wear eye protection." and this has stuck with me. Keeping always at hand a way to flush with large amounts of water (garden house) is a good idea too.

Andrew Ray wrote:AFAIK, vinegar should work. Suffice it to say the best protection for eyes are goggles, and worthwhile. My 7th grade science teacher, seeing that my passion for pyromania couldn't be dissuaded said, "Andrew, at least always wear eye protection." and this has stuck with me.

LOL, I'll say that to my kids when they can't be persuaded to give up dangerous activities.
I can just see it:
"Johnny, get off the roof..."
"No, Johnny, just because you have a Superman cape doesn't mean you can fly..."
"No, a Batman toolbelt doesn't mean you can throw the Batarang to slow your fall..."
"OK, well at least wear eye protection."

Dave Redvalley wrote:The biggest difference is the depth of discharge (DoD) that you can achieve with these batteries. Lead acid batteries should really only be discharged to 80% max, while the NiFe's can routinely be drawn down to 20% with no damage, thus the 3 times smaller battery bank, with better performance. I do like that math by the way, I see now problem with it at all! LOL. The only reason I have a 24v system vs. 48 or 12 is that is what it was when we bought the place. I would rather spend the money on the batteries than on replacing all of the inverters and switching gear. The 24v seems to be working good for us.

Dave,

I have no doubt the NiFe batteries can take a lot of pounding, and can survive extended discharge without damage (no small feat at all!), but what you wrote is not technically true. BTW: 80% DOD and 20% SOC are actually the same thing -- these terms are inversely related.

Flooded (true) deep-cycle lead-acid batteries (like Trojan T-105, L-16, etc...) are designed to withstand a depth of discharge -- or DOD -- of up to 80%. That means a state of charge -- or SOC -- of 20%, but they should be promptly re-charged, and the longer they sit in a discharged state (below their float voltage), the more sulfation occurs. Sulfation is normal, and can be reversed if the batteries are charged soon after discharge, but the sulfate crystals become more permanent the longer they are allowed to sit on the plates. After a while, they are more or less permanent, and can lead to reduced storage capacity and premature battery "death". If you size the solar array and so your loads only discharge the batteries by 50%, the batteries will last a lot longer. Another critique of the flooded lead-acid batteries is that even though the can handle this rough treatment, the more often it happens, the sooner they die. Sealed lead-acid batteries, either AGM or VRLA, are more like what you describe. They should never go below 50% and really should stay at 70% SOC or higher (30% DOD or lower) for good battery life.

NiFe batteries can be very deeply discharged, and can be left at a low SOC for extended periods without significant damage, and that is a really big deal. They are clearly better batteries, and we do need more companies to manufacture them.

As for the question about the battery bank voltage: most inverters are more efficient at 24 volts, and even better at 48 volts. Higher battery voltage affects the way the solar panels and batteries are wired, but higher voltage systems need smaller gauge wires and smaller gauge battery cables, and smaller gauge wire means a lot less copper or aluminum. If your solar panels are a long distance from the batteries and charge controller(s), you can save a LOT on wire by designing your system to operate at higher voltage. I have a few customers with solar panels about 300' away from the house, and when voltage drop and all that are factored in, they saved about $1000 on copper wire by using a 48-volt inverter.

Brad Vietje wrote:As for the question about the battery bank voltage: most inverters are more efficient at 24 volts, and even better at 48 volts. Higher battery voltage affects the way the solar panels and batteries are wired, but higher voltage systems need smaller gauge wires and smaller gauge battery cables, and smaller gauge wire means a lot less copper or aluminum. If your solar panels are a long distance from the batteries and charge controller(s), you can save a LOT on wire by designing your system to operate at higher voltage. I have a few customers with solar panels about 300' away from the house, and when voltage drop and all that are factored in, they saved about $1000 on copper wire by using a 48-volt inverter.

Yep, good points all. +1
I knew that, but was wondering why Dave had the 24V setup.

I was just gifted a 48V inverter and panel, and have yet to decide what to do with it. NiFe bank is not in my budget (yet), but I'm hoping to get something together by this fall.

@ All posters: Thanks for all the great info on the topic! I had not seen this covered before, and I appreciate it.

I lived with NiFe batteries for many years, they are very durable! The voltage range (from below 10 to over 16.5 for a 12 volt nominal set) can be a huge challenge, DC light bulbs and other dc items can easily cook. AC loads through an Inverter are a better option, though the inverter must be compatible with the voltage range to make full use of the batteries.

Brad Vietje wrote:Hey Cam,

The Iron Edison batteries do look like great performers, but don't be lulled into thinking that a strong alkali is any better than a strong acid. In fact, some solar pro's are worried that the electrolyte could even be worse, since all you need to clean up a battery acid splash is baking soda. There are concerns that getting the alkaline solution in your eyes, for example, might be worse that hydrochloric acid.

The incredible long life is absolutely spot-on, though, and I agree that if there was greater demand, and more manufacturers, the price would be a lot more reasonable.

Clear skies,

Brad Vietje
Newbury, VT

Howdy! my quick 2cents on this note. From my small amount of study, it apear's the NiFe batteries traditionally utilize KOH solution as the electrolyte.

I have been working with very strong KOH (leached from from oak wood ash) for many years buck-skinnig animal hides. It is not *particularly* dangerous in my experience. I have had my skin exposed to strong KOH solutions of ~pH9 and nothing but a dryness (like dishpan hands) occured. More or less the same as if you get Portland Cement on yourself. Not great, but not *particularly* dangerous in my estimation/experience.

Also, KOH can be quickly neutralized with common vinegar. Either white distilled or apple cider. I know that we always have lots of vinegar around the farm. Either purchased or made from apple cider.

KOH is also endogenic. it comes from the land and the land knows what to do with it. It can be easily and safely treated by dillution with water (no need to nuetralize) and be applied to fields/gardens as a Potash ammendment. That is how I handle my solutions and the pasture I've been speading it on loves it.

If you need to power a DC load, it isn't a problem today. Switch-mode power-supplies (such as one encounters for charging cell phones or laptops) can be designed for a variable DC input voltage and fixed DC output voltage. So if you are really fond of 12V electric appliances, no need to fear NiFe...

In the case of an input from 10 to 16V you'll need a buck-boost converter to get 12V output.

You can see these batteries are pretty pricey.

http://ironedison.com/nickel-iron-ni-fe-battery

12 volt 100 Amp hour will cost $970.00

This is the company that was featured on the PV podcast.

Maybe better to order direct from the manufacturer in China, if there is a large enough group interested?

www.alibaba.com yields several suppliers, and seems that they are shipped without liquid electrolyte, so that would save on ground freight expenses (ground freight tends to take into account weight, while ocean freight not as much, both of course are concerned with size).

This is what got me to permies in the first place.

How about a repeatable plan:

Make up for quality with quantity.

5 gallon buckets and home depot materials will yield less efficient but far less expensive 'cells' that when hooked up in series and eventually charged, run a lifetime.

I am thinking corrugated zing coated steel and aluminum cans with toilet cleaner?

Even if the don't last 50 years, they can be repeated...

Come on, help me out with 'kitchen chemistry' instead of rare chemical reactive science. The original description from Edison's writings was rusty metal and nickel...both pretty available then and HOK.

Steven Harris just sent me this email:

I own NiFe batteries, I have since 1994. I know them well. The BIG reason to NOT buy them, they are incredibly expensive, they are charging you 9x the price of a lead acid and guarantying you only 5x the life. NiFe batteries are VERY inefficient, which means a significant fraction of the energy you put in, does not get stored, something like around 25%. They are VERY VERY gassy, that is why there is such a huge head space on them to hold SO MUCH extra water, which MUST be distilled water ONLY. They have a high rate of self discharge, so if you just leave them there, they can loose 10% or more of their charge PER DAY.

so yeah...they have a very long life, but everything else they have is a huge disadvantage.

Needs to be nickel. Nickel costs (in quantity) about $20/kg. Compare to lead which is about $2/kg

An interesting site I found with some notes on homemade NiFe batteries:
http://www.noonco.com/edison/improvements.htm
(the author of this site is also the author of the Nuts and Volts article linked earlier)

His cell, which he clearly has given a couple of years working on, has extremely limited capacity.

He spells out how Edison made the early cells, and that is a possibility for the DIYer-- drill hundreds of holes in 1/2" steel tubes, nickel plate the tubes and pack them with a combination of Nickel Hydroxide and Nickel flakes; likewise make tubes from steel and iron oxide powder.

I suspect, if one took the time to drill hundreds of holes in meters upon meters of pipe, ones cash outlay on materials and supplies might come out ahead by a bit... but its often hard to beat the Chinese...

In all the comments I haven't seen the one problem I've heard about NiFe and that is self discharge. i.e. If you just store them, they will go dead. Wikipedia lists self-discharge at 20-30% per month. That seems like a lot to me. I think the better storage system is micro-hydro or pneumatic. Either avoid an awful lot of nasty chemicals and are proven and popular technologies.

Richard Hauser wrote:In all the comments I haven't seen the one problem I've heard about NiFe and that is self discharge. i.e. If you just store them, they will go dead. Wikipedia lists self-discharge at 20-30% per month. That seems like a lot to me. I think the better storage system is micro-hydro or pneumatic. Either avoid an awful lot of nasty chemicals and are proven and popular technologies.

I think you might have missed Paul's post regarding Steve Harris' response RE: NiFe batteries:

Steve Harris wrote:They have a high rate of self discharge, so if you just leave them there, they can loose 10% or more of their charge PER DAY

This is a concern, but I think it gets lessened somewhat by using a mix of potassium hydroxide and lithium hydroxide.

As far as being gassy, I have heard some talk of using the off-gassing hydrogen to run through a hydrogen fuel cell, which does make good use of a "waste" resource. (Permaculture, anyone?)

I'm not sure how you would do microhydro "storage", unless you had multiple raised tanks or reliable falling water (high pond, stream, etc.), though it would be a good continual power source.
That's not going to work in my southwest, however, dry as it is.

Pneumatic is something that's interesting, and something I've considered.
Downsides are: it can get expensive, and you must have enough tanks and solid lines, and buy/acquire more tanks to increase storage.
There are (thermic) losses due to compression. Air compressors wear out rather quickly when used at a 100% duty cycle.
A sudden explosive release is in my opinion, though, nearly as dangerous as chemicals.

I'm not an evangelist for Ni-Fe batteries, and I don't think they are the best solution in every situation. We have to remember that they are 100-year-old technology, after all.

As an aside, why in the world haven't we come out with a better battery technology? Lithium ion? Really? That's the best we can do?

I've thought for a long time that the two things holding back humanity from technological progress are:
1) Efficient energy storage
2) Real nanotechnology

Yes, sorry, I missed Paul's post. Both he and I got are info from the same source as I asked Steve about NiFe batteries 6 months ago and he gave the same response. As for changing the chemistry, that is possible, but I believe outside of the field of this forum. If there are amazing chemists here great, but until you can show an altered chemistry that solves the issue, we have to deal with the existing technology. When that happens, I will happily withdraw my concerns and praise your achievement.

From my research, I've actually come up with four technologies that seem better to me and available to this audience. The fifth is a fuel cell which seems outside this audience though the alcohol versions may not be. I assume the hydrogen versions are, but again I would be happy to be proved wrong.

The first usable tech is microhydro, which is the pumping of water up to the top of a hill to store in a pond. On my property I have a 300' hill and if I could build a windmill to pump water from the stream at the bottom up to a pond at the top, I could then set up a microhydro generator which could then power the property as needed. On flatter ground, I agree that a tower could be used, but the stored energy would likely be too low to be of much use. Even with my situation the pond has to be very large to provide much storage, though I don't have good hold on what .001 MJ/kg is, (http://en.wikipedia.org/wiki/Energy_density) but you have to be at least a little impressed that once set up, it rains electricity. Also even if you don't setup microhydro, you can still use it for irrigation, so no effort is wasted. The disadvantages are that it is immobile, you need to have key situations in place to make it even possible and there will be pumping losses due to pipe friction and pumping inefficiencies. The advantage is that there is little or no self discharge and the tech is proven and used by the power companies.

The second tech is pneumatic storage which is also used by power companies. As stated pneumatic storage suffers from thermic losses due to compression and there will also be thermic losses at expansion. There will also be temporary thermic losses due to cold weather or possible over pressure losses due to hot weather. As for the the danger of energy storage, well that problem is universal. The more energy you store, the more danger you have. Even that pond on a hill can kill you. I think many of the issues can be mitigated by doing larger lower pressure storage. If you took a 500 gallon propane tank and then wrapped it with fiberglass for reinforcement and installed a pair of burst valves, you would end up with a storage system as safe as any battery and with minimal maintenance and care, one that could last nearly forever. As for the durability of an air pump, I would point you to an automotive AC compressor which can last decades, even in cars in Florida. The issues with reliability are related to use of home air compressors where they limit oil injection because many uses need "dry air". We want our air wet, which will go a long way in saving all the moving bits. On the flip side pneumatic storage can make use of stored thermal energy, so if you pipe the output of your pressure tank through a pipe that is heated by your RMH, but keep it under the smoke point for the oil, you turn that heat into usable energy. You could make this system mobile by storing the thermal energy in molten salts. Pneumatics are a proven technology is use all over the place. The Amish call it "Amish electricity" to power their kitchen appliances. You can buy a pneumatic chainsaw. Why not make a pneumatic tractor? They are making pneumatic cars and motorcycles. I understand that those are using extremely high pressure systems, but that is not a requirement, it just increases energy density.

The second tech points to the third tech, thermal storage. Nothing too crazy, but the phase change of melting Potassium Nitrate can store a lot of energy. This can then be converted using pneumatics, steam engines, Stirling Engines or Peltier chips.

The last energy storage is the one we are most accustomed to, wood. Wood has 1/3 the energy by weight as gasoline and that statistic still blows me away. To convert wood into usable energy we need to burn it and then use that thermal energy to run a motor: again pneumatics, steam engines, Stirling Engines or Peltier chips. Of the group the most efficient is the Stirling engine. These are generally dismissed as unworkable (the head of the Stirling Society has a diesel engine converted to a steam engine as a backup power source) but there is one thing that makes me think it is possible and accessible by this audience, rolling sock seals. You see most people build seals by creating close tolerances between machined parts, but as anyone who has seen an air piston on a truck brake will tell you, there is another way, use a flexible fabric to seal the two pieces together in such a way that the fabric unrolls to allow the piston to move. This system is used in both the Philips MP1002CA and in a new motor created by a company called Sunvention http://www.solarheatengines.com/2012/01/10/tamera-video-of-sunvention-sunpulse-engine/. The later uses the sun to heat oil to run the motor, but could also use a RMH to heat the oil to run the motor.

Richard Hauser wrote:
The first usable tech is microhydro, which is the pumping of water up to the top of a hill to store in a pond. On my property I have a 300' hill and if I could build a windmill to pump water from the stream at the bottom up to a pond at the top, I could then set up a microhydro generator which could then power the property as needed. On flatter ground, I agree that a tower could be used, but the stored energy would likely be too low to be of much use. Even with my situation the pond has to be very large to provide much storage, though I don't have good hold on what .001 MJ/kg is, (http://en.wikipedia.org/wiki/Energy_density) but you have to be at least a little impressed that once set up, it rains electricity. Also even if you don't setup microhydro, you can still use it for irrigation, so no effort is wasted. The disadvantages are that it is immobile, you need to have key situations in place to make it even possible and there will be pumping losses due to pipe friction and pumping inefficiencies. The advantage is that there is little or no self discharge and the tech is proven and used by the power companies.

The idea of a pond at the top of a hill has been passed around a bit. It seems to me the self discharge was considered quite high due to evaporation and seepage. In some situations rain may make up for that, but even so the self discharge is there. (In many cases people use the term "leakage" instead of self discharge which may make more sense here)

The second tech is pneumatic storage which is also used by power companies. As stated pneumatic storage suffers from thermic losses due to compression and there will also be thermic losses at expansion. There will also be temporary thermic losses due to cold weather or possible over pressure losses due to hot weather. As for the the danger of energy storage, well that problem is universal. The more energy you store, the more danger you have. Even that pond on a hill can kill you. I think many of the issues can be mitigated by doing larger lower pressure storage. If you took a 500 gallon propane tank and then wrapped it with fiberglass for reinforcement and installed a pair of burst valves, you would end up with a storage system as safe as any battery and with minimal maintenance and care, one that could last nearly forever. As for the durability of an air pump, I would point you to an automotive AC compressor which can last decades, even in cars in Florida. The issues with reliability are related to use of home air compressors where they limit oil injection because many uses need "dry air". We want our air wet, which will go a long way in saving all the moving bits. On the flip side pneumatic storage can make use of stored thermal energy, so if you pipe the output of your pressure tank through a pipe that is heated by your RMH, but keep it under the smoke point for the oil, you turn that heat into usable energy. You could make this system mobile by storing the thermal energy in molten salts. Pneumatics are a proven technology is use all over the place. The Amish call it "Amish electricity" to power their kitchen appliances. You can buy a pneumatic chainsaw. Why not make a pneumatic tractor? They are making pneumatic cars and motorcycles. I understand that those are using extremely high pressure systems, but that is not a requirement, it just increases energy density.

This is an interesting technology. I have seen a number of prototypes but no production. It is something I would like to try though. I don't know the ins and outs so far as leakage or other losses. To be honest, the fact that a power company uses something does not speak to me of goodness. The numbers on how much of the power that starts from the source makes it to the end is pretty sad.

The second tech points to the third tech, thermal storage. Nothing too crazy, but the phase change of melting Potassium Nitrate can store a lot of energy. This can then be converted using pneumatics, steam engines, Stirling Engines or Peltier chips.

one hopes there is also a good use for all the waste heat. This particular example probably makes batteries look good if you look at energy in as compared to energy out. This one of those technologies where size matters. Where what works for megawatts, may not work so well for kilowatts. Just the heat storage alone would show that... sphere shaped storage would be best and the bigger it is the more the heat storage medium acts as part of it's own insulation... and the lower the percentage in size the outside insulation has to be. I actually believe in heat storage very strongly, but storage of heat for power.... needs work.

The last energy storage is the one we are most accustomed to, wood. Wood has 1/3 the energy by weight as gasoline and that statistic still blows me away. To convert wood into usable energy we need to burn it and then use that thermal energy to run a motor: again pneumatics, steam engines, Stirling Engines or Peltier chips. Of the group the most efficient is the Stirling engine. These are generally dismissed as unworkable (the head of the Stirling Society has a diesel engine converted to a steam engine as a backup power source) but there is one thing that makes me think it is possible and accessible by this audience, rolling sock seals. You see most people build seals by creating close tolerances between machined parts, but as anyone who has seen an air piston on a truck brake will tell you, there is another way, use a flexible fabric to seal the two pieces together in such a way that the fabric unrolls to allow the piston to move. This system is used in both the Philips MP1002CA and in a new motor created by a company called Sunvention http://www.solarheatengines.com/2012/01/10/tamera-video-of-sunvention-sunpulse-engine/. The later uses the sun to heat oil to run the motor, but could also use a RMH to heat the oil to run the motor.

this is the starting point for most people because it is accessible. There is also a very valid point that can be made that heat from wood may for many things translate directly to final use rather than to power first. It is probably more effective to light directly from fuel rather than from power made from the same fuel. I would like to see work done on lighting without electric power. Certainly using wood to make power for cooking is laughable.

These ideas are not garbage, but they are under development, not yet to the emerging technologies state yet. Someone who is powering a house with a system that must work all the time often when the only person around has no clue what a breaker does let along anything more, needs proven technology which means batteries. These other things would be great for use along side the main system, but I don't think to many people are willing to bet their whole reliance on these technologies yet.

If it was me... and I had the money to dabble, I might try them all so that each one was a backup for the others.... there might still be a genset, hopefully never being used, around too. NiFe batteries are far from the worst solution, some people prefer the trade-offs from lead acid. I think there are some other technologies in batteries that may be better than both. I think that it may depend on the use too and may be worth while using one kind in one use and another somewhere else. I personally would like to try NiCd batteries. They have a similar entry cost to NiFe, but several advantages too. They may not look very good in the aa size , but compared to lead acid or NiFe, they start to look much better.

Richard Hauser wrote:
<...>
The first usable tech is microhydro,
<...>
The second tech is pneumatic storage
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The second tech points to the third tech, thermal storage.
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The last energy storage is the one we are most accustomed to, wood.
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There's a wonderful blog called Do The Math, written by a physics prof at UC San Diego. I'm going to link to one particular article here in a second, but before I do, I feel like I should promote him a little bit- just about every single thing he's written there has been pure gold. He goes into specifics on all of these energy topics, and like the titled of the blog suggests, he goes through an issue and does the math.

I'd encourage EVERYBODY who's interested in alternative energy to go to the beginning of his archive and read all his articles . They're a magnificent education. But I'll spoil the ending for you, too: the main answer to the world's electricity needs is a photovoltaic system on most roofs. The world's need for liquid fuels just has to shrink. That what he says, anyway.

Ok, back to the point. The author takes up these exact issues here:
http://physics.ucsd.edu/do-the-math/2011/09/got-storage-how-hard-can-it-be/

Here are some of the highlights.

Let's start small by considering the 3 W-h of energy stored in a AA battery, as computed above. One kWh of energy is 3.6x106 J of energy, so our AA battery stores 10,800 J of energy. A mass of m kilograms, hoisted h meters high against gravity at g=10 m/s^2 corresponds to E = mgh Joules of energy. If we were willing to hoist a mass 3 m high, how much mass would we need to replace the AA battery? Have a guess? The answer is 360 kg, or about 800 lb. A battery the size of your pinky finger beats the proverbial 800 lb gorilla lifted onto your roof!
The lesson is that gravitational storage is incredibly weak. A volume of water the size of our bedroom raised even 10 m above our home in a precarious threat to the neighbors would store 0.625 kWh. That’s enough for 30 minutes of typical household electricity consumption. You’ll forgive me if I ignore efficiency losses. It’s not even worth the effort.





Electrolysis for the production of hydrogen tends to range between 50-70% efficient. Then the fuel cell converts the stored energy back into electricity at 40-60% efficiency for a round-trip efficiency of 20-40%. If you happen to want some of the waste heat, then you might boost the efficiency estimate (true for any of these storage methods, actually). But in a straight-up apples-to-apples comparison, the hydrogen method is a very lossy storage option. If it were dirt cheap and low-tech, I might be more excited about its potential, despite the poor efficiency. But since the opposite is true, I’m not revved up over hydrogen storage.

I spent some time searching for a hydrogen fuel cell that I could buy today with a rating in the 10 kW range (appropriate for a home). I saw some production models achieving efficiencies ranging from 40-53%, but never a price tag. If you have to submit a query to learn the price, you probably can't afford it...





We could store energy in something akin to a spring by compressing air.
The efficiency for compressing the air and later turning a turbine for electricity generation may be less than what one might find for a flywheel. The storage itself is not the hard part. I could go out today and get some lab-sized cylinders (~50 liters), which could store 1.5 kWh each- about like a golf-cart battery, although heavier and bulkier. But I would have a very difficult time arranging an efficient pumping and extraction/turbine system. If not for that, I would find compressed air to be an attractive system compared to batteries: minimal maintenance; no apparent cycle limitations, reasonably low-tech, and perfectly tolerant of remaining at low charge indefinitely.

I second Mike's endorsement of Do the Math. It is outstanding. Read it. You won't be disappointed. A good basic foundation in physics makes it possible to cut through a lot of BS.

Richard Hauser wrote:
The last energy storage is the one we are most accustomed to, wood. Wood has 1/3 the energy by weight as gasoline and that statistic still blows me away. To convert wood into usable energy we need to burn it and then use that thermal energy to run a motor: again pneumatics, steam engines, Stirling Engines or Peltier chips. Of the group the most efficient is the Stirling engine. These are generally dismissed as unworkable (the head of the Stirling Society has a diesel engine converted to a steam engine as a backup power source) ...

Just a quick correction. You may be referring to Ken Boak of the UK here. He was once the head of the UK Stirling Society. However, note that he does not use a steam engine, but a Lister Diesel engine converted to run on wood gas.

This thread started on NiFe batteries and went to energy storage in general (electricity in particular). Some problems with NiFe were noted, but the main problem seems to be its high cost. In my opinion, NiFe is simply far too costly to be a practical option. It seems only the zealots (and wealthy ones) remain unconvinced. Don't get me wrong, I like them - they're just too damned expensive.

The most cost effective alternative that I have seen so far is a new forklift battery. I priced a unit recently (see www.giantbattery.com). A 24 volt, 800 amp hour (at 20 hour rate), 1100 pound unit was quoted at $2453 with price including delivery in the continential U.S. There is a 7 year warranty on defects, and the battery is rated for 1500 full cycles. My research shows that 10 years is a conservative estimate for the operational life of these batteries in the off grid renewable energy setting. I've seen several accounts at 15-20+ years. The same company also picks up discarded batteries without charge, so you know they are recycling batteries for compensation. I did not verify, but it seems a significant discount on a new battery could be demanded when presenting a discarded battery in trade, and this should lower costs further.

A lot of lead acid batteries seem to die inside of 5 years in the RE setting. Long term battery costs get very high in that case. If the forklift battery will deliver 10+ years of service, and do so reliably (and all evidence I've seen shows that it will deliver), then it seems hard to beat. If anyone knows of a more cost effective alternative, then please let us all know.

NOTE: On the massive size and weight of a forklift battery, a practical solution for this seems to be placing the unit onto a platform on heavy casters. A battery could be delivered and placed onto the platform, then maneuvered to the desired location. I have moved large safes on several occasions using this approach, and I've found it to be a practical solution.

Marcos Buenijo wrote:
The most cost effective alternative that I have seen so far is a new forklift battery. I priced a unit recently (see www.giantbattery.com). A 24 volt, 800 amp hour (at 20 hour rate), 1100 pound unit was quoted at $2453 with price including delivery in the continential U.S. There is a 7 year warranty on defects, and the battery is rated for 1500 full cycles. My research shows that 10 years is a conservative estimate for the operational life of these batteries in the off grid renewable energy setting. I've seen several accounts at 15-20+ years. The same company also picks up discarded batteries without charge, so you know they are recycling batteries for compensation. I did not verify, but it seems a significant discount on a new battery could be demanded when presenting a discarded battery in trade, and this should lower costs further.

A lot of lead acid batteries seem to die inside of 5 years in the RE setting. Long term battery costs get very high in that case. If the forklift battery will deliver 10+ years of service, and do so reliably (and all evidence I've seen shows that it will deliver), then it seems hard to beat. If anyone knows of a more cost effective alternative, then please let us all know.

We quite often replace those batteries in 5 years... but that is in their intended use in a forklift. Also our drivers abuse them (and the FL) a lot. It is not uncommon to see a driver use a FL to push 10 fully loaded monos (A mono is a meter cube and the FL is rated to handle 2) across the floor and then wonder why the battery is getting hot or why a fully charged battery is flat in two hours instead of eight. RE use should be much lighter. The up side too is that these come as single cells in a steel case the case has loops made for lifting/moving them (lifting with a chain fall, not your back). Single cells can be replaced, but generally are not.

NOTE: On the massive size and weight of a forklift battery, a practical solution for this seems to be placing the unit onto a platform on heavy casters. A battery could be delivered and placed onto the platform, then maneuvered to the desired location. I have moved large safes on several occasions using this approach, and I've found it to be a practical solution.

We often move that size battery on a wheeled trolley, it is no problem. We also have some twice that size (one ton) that we do not. (the big ones get lifted and moved with a hoist)

Just found out about these batteries yesterday, cool old technology. Wondering how they do in the freezing cold, I see lots of conflicting information? What would performance be like at 0 deg c of one of the modern manufactured units? any problem with them working upside down, leakage?

John Master wrote:Just found out about these batteries yesterday, cool old technology. Wondering how they do in the freezing cold, I see lots of conflicting information? What would performance be like at 0 deg c of one of the modern manufactured units? any problem with them working upside down, leakage?

Old flooded plate tech must be right side up... just like a glass of water. I don't think I would want to freeze them any more than lead acid batteries, but I also don't know what the freezing point of the electrolyte is... lower than fresh water for sure though. The manufacturers specs should cover all of these questions though.

These are big heavy batteries meant for stationary use. Bigger than lead acid. The upside down issue should not come into play.

From what I've seen and the instructions that came with my batteries for mixing the electrolyte you can adjust the specific gravity of the mix to compensate for colder temperatures while maintaining battery performance. That being said I would place the batteries in an environment with a relatively stable temperature otherwise you would be looking at replacing gallons of electrolyte with the change of seasons. And you could definitely not mount them upside down....huge mess, quickly!

the reason I ask is that I saw these advertised as being used in vehicles, military, high vibration use and didn't know if they are well sealed or not. Was thinking of using them for an off road winter electric vehicle but if they wont even work below freezing (or if the performance falls off so badly that they are essentially useless) then it is an instant no for that kind of use. If they leak or work poorly upside down (which would happen a few times per day in use) then I will just keep them in mind if I ever get off the grid.

Read somewhere that the electrolyte concentration can be changed to work better in the cold? Just wondering how cold. I think 0 deg F would be about the extent.

I had a thought of using a rep-rap 3D printer to print HDPE boxes to use for the battery banks and then electroplating plates of steel to get the nickle side ready. I would think that could get the costs down. Maybe we could create an open source wiki page and come up with a great design that could be loaded into printers and CNC. We could also design in ports to catch H2 as well as make it easy to fill with distilled water, say from an elevated cistern.

Jason Learned : I Think these are all excellent ideas, I am still trying to wrap my head around 3-d printing technology, which takes an amazingly small amount of
programing/ computer power, and already is a match to CNCs for some simple jobs ( printing up replacement wear surfaces on G Es Diesel Locomotives )

I am assuming that the comment about catching H2 was a 'throw it out there and see what outer people think' , or off of the top of your head, ( which is just the kind of -
thinking we need !) You were thinking that capturing the H2 would allow its storage and use? Unfortunately H2 is so tiny and slippery that Chemists have told me that it
just pours out though the atomic sized holes found in all (?) glass ! Finding out how to channel the escaping hydrogen for immediate use, or at least onsite storage and
release is the easy side of the current crop of hydrogen fuel cells !

John Master I do not have a clear picture of why you have an expectation that a tip over event would be common. My thoughts are with all that road-hugging-weight
low in the center and possibly on gimbals your problem could have a solution ? !!!

Just a couple of cents worth of my thoughts ! For the craft! Big AL !

I was thinking the low pressure storage system that the angel's nest earthship used before it got foreclosed on and they tore out all the machinery. I suppose Hydrogen would be lost and it might not be worth the effort, however, if the battery bank was big enough and you could see a large use of water then I would think putting in something like this could be useful. Steve Harris' friend Roy McAlister uses steel and carbon high pressure tanks, but that would require a great deal of H2 production.

A question that might be worth researching if this were to progress. How much charge would be lost while the batteries sit and how much H2 run through a fuel cell would be required to maintain the charge? Maybe it could slow the discharge down to a lower percentage. Could all of this be built in a home shop and could it be done cheaply?