Windpower Engineering & Development

  • Home
  • Articles
    • Most recent posts
    • News
    • Featured
  • Resources
    • Digital issues
    • Podcasts
    • Suppliers
    • Webinars
    • Events
  • Videos
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
  • Magazine
  • Advertise
  • Subscribe

Advanced lead-carbon (PbC) battery sports advantages for grid stability

By Paul Dvorak | April 24, 2014

Power storage may be the big story in renewable energy in the next few years, thanks to a proliferation of battery chemistries. Lithium-ion varieties, however, may be overshadowing other chemistries, such as flow batteries and the always evolving lead-acid. Consider, for example, Axion Power International’s (www.axionpower.com) lead-carbon, or PbC battery. The company calls it an advanced lead-acid design because it replaced the negative lead plate with an activated carbon plate giving the battery unusual characteristics, such as super-capacitor qualities. In addition, the PbC design uses the same caustic plate as a lead-acid battery along with components, casing, and electrolytes, and it’s recyclable.

Axion’s PbC batteries look like conventional car batteries, but come in 12 and 16V, and weigh about 30 to 35% less. The company builds these into 480V racks and those into utility scale power stores called PowerCube.

Axion’s PbC batteries look like conventional car batteries, but come in 12 and 16V, and weigh about 30 to 35% less. The company builds these into 480V racks and those into utility scale power stores called PowerCube.

“The failure mechanism in a conventional lead-acid battery is the negative plate,” says Axion CEO Tom Granville. “So we have taken the lead completely out of the negative plate and only use it in the positive plate.” The result is a battery that lasts three to four times longer than a conventional design.

An inherent and more useful property of the PbC battery is the activated carbon plate’s tendency to control charge rate. When charging a string without a battery management system, the batteries equalize without intervention. The battery with a low charge has a low internal resistance, so it accepts the most charge; batteries with a higher internal charge have a higher resistance, thus resisting the charge. Even when not charging, the string voltage supports one another. Additionally, a typical lead-acid battery close to 100% could be over charged, causing it to emit gas, dry out, lose design function and eventually expire.

Performance comparisons

The stacked plates make a 2V cell.

The stacked plates make a 2V cell.

With reference to discharges, Granville says some lead-acid battery manufacturers talk of 100% discharge, but they really mean 80% because the last 20% is unusable. Typically, the PbC battery operates at about 80% state of charge.

“We have taken the battery to zero charge and back again for more than 2,500 cycles. By comparison, the website for a top of the line lead-acid battery mentions 550 cycles,” he says.

Consider the recharge rate for comparisons to other batteries. The Axion design recharges about twice as fast, and in some cases, four times faster than other battery chemistries – including lithium-ion. In addition the PbC charge acceptance far exceeds that of its lead-acid competitors, especially over time. In the first couple of months on the job, a lead-acid battery has good charge acceptance characteristics, but these characteristics are lost as lead crystals begin to form on the negative plate. That is, as lead-acid batteries age, their ability to accept charge – in partial state of charge applications – significantly decreases, especially when compared to a PbC battery.

A look inside a PowerCube shows several 480V racks.

A look inside a PowerCube shows several 480V racks.

“So six months out, the PbC design charges four times faster, and nine months out, about 10 times faster than conventional lead-acid batteries,” says Granville.

Lithium batteries’ also take longer to recharge than PbC because of the heat factor created in recharging. So in applications such as frequency regulation, the need for fast continual recharging will create heat and reduce the battery’s ability to fully function. Of course, the heat build up also affects Lithium batterys’ life expectancy.

Cost comparisons with other batteries depend, of course, on the application. With regard to cost, the PbC design is approximately one and a half to two times that of an advanced lead-acid battery, but Granville says Axion’s battery will last four times as long.

“For a few comparisons with Lithium chemistry, if we are talking about Li-phosphate, we are approximately 30% cheaper. If the comparison is to Lithium titanate, then we are about one-third the cost,” he clarifies.

Frequency regulation

The PowerCube on Axion grounds is connected to the PJM grid.

The PowerCube on Axion grounds is connected to the PJM grid.

The whole point of power storage is to stabilize the grid by regulating frequency. For this task Axion builds the PowerCube, a scalable megawatt storage system in a custom shipping container.

“The idea is to keep the line frequency in balance, keep a level sine wave,” says Granville. “The further out of synch line frequency gets, the more power it takes to bring the system back into balance. For instance, if 1 MW out, it might take 2 MW to bring it back in, if 2 MW out, it might take 6 to bring it back in, and so on. So it behooves the utility to correct the frequency and bring it back as soon as possible.”

Demand response programs allow for the PowerCube to go online within milliseconds of receiving a power request from the utility through the Connection Service Provider (CSP).

“Power requests are almost continuous. The utility provides payment in one hour increments, even if it only needs the power for a minute. So we sort of hopscotch from one request to the next,” Granville adds.

Utilities have moved toward a pay-for-performance model, meaning the faster a power provider can respond to them, the more it gets paid. Granville says the Axion system responds in 55 ms.

“When that utility started the program, it was taking about 15 minutes to respond to a power request. That was further trimmed to three minutes, and that kicked out some batteries that could not respond quickly enough. Our score, on a scale of 0 to 100 with 70 as passing, has averaged over 94 since we began participating in 2011,” he continues.

In the frequency regulation market, the battery does not discharge much more than 30 to 35%. In this application, Granville says the chemistry is capable of hundreds of thousands of such cycles. What’s more, there is huge demand this winter for frequency regulation. The PowerCube on the company’s site has been tied into the PJM net since November 2011, allowing the company to participate in the regulation task every day. PJM pays Axion to accept an electrical charge from them and to in turn provide it in a demand response application.

To assist with other applications, the company developed a math model to simulate them. “We worked with the CSP to establish a minimum bid,” Granville explains. “We bid in at the rate of say, 5 ¢/kWh minimum, and if the utility accepts, (or if it is paying a higher rate, that higher rate number pertains) that is what we are reimbursed. The PowerCube lets us become a spot market provider for them. If you can believe it, for a short period in January, they paid more than $2,800/kWh because power demand was so great. That figure, however, is by far the largest amount paid in the last 2.5 years.”

Granville adds that the company’s system model is well established. It suggests a PowerCube owner would be paid a gross figure of about $250,000 a year per MW (the CSP charges a percent for their part in the transaction).

“The good news for solar now is that if an installation includes power storage, the developer gets the 30% tax credit on the whole system and 30% on the battery storage component as well. Utilizing our model, that can provide a return of investment in 4 to 4.5 years,” Granville says. WPE


Filed Under: Energy storage, News
Tagged With: axion
 

About The Author

Paul Dvorak

Comments

  1. Troy Johnson says

    October 19, 2015 at 8:56 am

    Update.

    Unfortunately, Axion’s PbC battery failed to gain commercial acceptance. By anyone:

    ePower: PbCs overheated in ePower’s truck testing. ePower is testing other battery chemistries.

    Norfolk Southern: NS declared the PbC uneconomical for use in a yard switcher. Testing in an Over-The-Road locomotive seems destined to some far-off future date, if ever.

    BMW and Toyota/Kia: BMW tested the PbC for years but never placed an order. Toyota/Kia morphed from automotive to trucks then to the dustbin. Axion no longer mentions automotive in any of their shareholder communications, which of course means that automotive is mothballed at best, and dead at worst.

    Stationary: Only one order was ever received, and it was small and for a project that was troubled. The PbC was to be the battery for a second, unrelated project, from an even more unknown vendor, but that project was even more troubled and never even produced an order.

    The consequence of this failure to achieve sales was the destruction of Axion’s financial condition, the loss of its CEO, CFO and Chief Marketing Officer, and the plunge in its stock price by over 99.9%. An attempt by a Chinese businessman was made to partner with Axion for the Chinese market, but that attempt also ended in failure. Currently, AXPW the stock is in the control of day trading speculators.

    Sad ending to a technology a few hopeful souls once thought had some promise.

  2. naresh vangapally says

    June 30, 2014 at 6:04 am

    what is the current collector used.if its made up of lead /carbon.if it it is lead \carbon what happened to the battery.

  3. Topcat says

    April 25, 2014 at 4:13 pm

    If you are interested in discussing a possible strategic relationship please contact Axion’s President and Chief Executive Officer Tom Granville.

    Customer Relations:

    Axion Power International Inc
    3601 Clover Lane
    New Castle, PA 16105
    (724) 654-9300
    (877) 324-9300
    (724) 654-3300
    info@axionpower.com

  4. nosouthwest says

    April 24, 2014 at 5:11 pm

    Axion Power stock ticker = AXPW

  5. wajo says

    April 24, 2014 at 4:47 pm

    For folks interested in following Axion, the Seeking Alpha.com website has a stock talk blog that keeps track of AXPW on a daily basis.

  6. Troy Johnson says

    April 24, 2014 at 4:42 pm

    Axion’s PbC battery is a real up and comer. Hardly anyone has heard about it, over the din from li-ion. Norfolk Southern picked it, over li-ion and a host of other chemistries, for use in their electric locomotive development. That application requires rapid recharge and good string balancing/simplicity in a wide range of operating temperatures.

    Axion is also working with BMW, either Toyota or Kia (NDA secrecy) and many other household names, as well as those that are not, such as ePower, a small hybrid truck developer who admits they wouldn’t even have a viable product without the PbC battery.

    After a long time developing its battery and its manufacturing, look for Axion to start making some big waves this year and next…

Related Articles Read More >

US government allows Empire Wind offshore project to resume construction
Richardson Electronics to deliver pitch energy modules to TransAlta wind fleets
Equinor halts work on Empire Wind offshore project after federal government order
ARESCA wants input on offshore wind standards

Podcasts

Wind Spotlight: Looking back at a year of Thrive with ZF Wind Power
See More >

Windpower Engineering & Development Digital Edition

Digital Edition

Browse the most current issue of Windpower Engineering & Development and back issues in an easy to use high quality format. Clip, share and download with the leading wind power engineering magazine today.

Windpower Engineering & Development
  • Wind Articles
  • Solar Power World
  • Subscribe to Windpower Engineering
  • About Us/Contact Us

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising

Search Windpower Engineering & Development

  • Home
  • Articles
    • Most recent posts
    • News
    • Featured
  • Resources
    • Digital issues
    • Podcasts
    • Suppliers
    • Webinars
    • Events
  • Videos
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
  • Magazine
  • Advertise
  • Subscribe