From Guest Blogger Brian McGowan: Power Storage
Many times the subject of power storage has come up on this forum. Today it becomes an issue for me personally again and this is an ongoing issue.
Not quite 3.5 years ago I purchased 4 deep cycle 12 volt 125 Amp hour (Ah) batteries for my little system to replace the ones I was using that had gone bad. That amounts to 500Ah of batteries for $400.00. These batteries are once again shot and I am in search of a replacement for flooded lead acid (FLA) batteries. With an expected life of 3-7 years at the very best these batteries are, in my humble opinion, completely unsuitable for the renewable energy industry. Also the recommended depth of discharge for a “long” life is 30% and preferable less meaning a 500Ah pack is really only good for about 166Ah. Add to that temperature considerations, max rate of charge and discharge and various other factors and the suitability goes downhill very fast. I am loath to go for FLA batteries again as they are unsuitable for renewable energy in so many ways, however, the alternatives are far more expensive in the short term.
Until such time as Dr. Doty gets his windfuels device running, or Eos energy gets their Zinc/air battery into some kind of sellable form or gives me a prototype to experiment with, the only currently viable alternative to FLA batteries is Edison type Nickel/Iron batteries. They are the only energy storage system that can stand being overcharged, undercharged, left dead for years and still take a charge without damage and are tolerant of temperature variations. Since the “ingredients for these batteries are Nickel, Iron and a solution of Lye and water, they are also substantially less toxic and much lighter than FLA batteries. These stopped being manufactured in the U.S. about 40 years ago and are only manufactured in China and Russia. There is one manufacturing facility in each of these countries making 2 facilities total for the entire world. Another shining example of the U.S. abandoning the best technology and allowing competing countries to gain a lead on is.
I have only found 2 places that offer new Nickel/Iron batteries and both import them from China.
http://ironedison.com/
http://www.beutilityfree.com/Electric/Ni-Fe
This place claims to make batteries here in the U.S. but I can’t verify that yet. Rumor has it they may be refurbing original Edison batteries but the pictures don’t look like originals. They are also the most expensive. I have to do more investigation.
http://www.zappworks.com/battery_prices.htm
I have more research to do but by back of the napkin calculations it is looking like Ironedison is the front runner right now.
Decades ago, AT&T used nickel iron (Edison) batteries for telephone systems. The batteries were continuously floated in such a way that when grid power went down, there would be no interruption in telephone service. They were also used in earlier times for electric cars. However, nickel iron batteries have limitations.
Nickel iron batteries have a much higher internal resistance than lead acid batteries and are less efficient, so in general, they are not suitable for engine starting. But for backing up solar or wind power on a small scale, they could work very well. On a large scale, the cost and somewhat low efficiency would make them unsuitable.
Probably the limited demand caused U.S. companies to stop making them. Nickel cadmium batteries were more efficient and had a lower internal resistance, but had a memory problem in that if they were not deep cycled, they would lose capacity, and cadmium was toxic. Eventually they were replaced with nickel metal hydride batteries.
You are right, standard deep cycle Lead Acid batteries are far from ideal as they tend to have poor cycle life especially in hot conditions.
There are new technologies becoming available but as you say, costs are still relatively high.
You might try looking into Lead Carbon batteries – an advanced form of Lead Acid batteries with carbon electrodes in which the lead is held.
The technology does not give opportunity for sulphation as Lead Sulphate crystals cannot grow beyond the nano scale, and corrosion is also not a problem due to the carbon electrodes. These batteries have very low internal resistance, high cycle efficiency and last for several times more cycles than conventional deep cycle batteries. They can also be discharged to a much higher percentage of their capacity whilst retaining a very much longer life than other Lead Acid batteries.
One supplier of these batteries is Rosewater Energy who supply batteries made by Axion Power
http://www.rosewaterenergy.com/residential.aspx
Decades ago these batteries were also installed in many farms without grid power before the rural electrification act. They would regularly last at least 25 years and when the solution was changed they would go for another 25 years. They happily go to 80%DOD every day without any damage at all. If distributed generation were implemented and these batteries were included in each system larger scale systems would be needed much less.
The reason they are not made here anymore is that there is not enough short term repeatable profit in a battery that will last 100 years with only minor maintenance every 25 years or so and the fact that a large push was made to attach everyone to the grid instead of making the effort to improve renewable energy.
As I am making the comparison, I am finding that getting the size of battery pack in FLA that I would need to accomplish the same thing in NiFe makes the initial cost difference much less and when you factor in how many times you would have to replace the FLA battery pack the NiFe becomes much much less expensive over the long haul. Production of these batteries should be started again here in the U.S.. Their advantages far outweigh their shortcomings.
I did look at Rosewater energy and it looks interesting but that will take some more investigation and I suspect their cost will be prohibitive at this time.