BOB, America’s Biggest Sodium Sulfur Battery, Powers a Texas Town

by , 04/06/10

Big Old Battery, BOB, Presidio, sodium sulfur batteries, battery powers Texas town, Electric Transmission Texas, batteries and renewable power, utilities use batteries, biggest battery in US

They say everything’s bigger in Texas. Apparently that’s true for batteries, too. Presidio, Texas, recently built a giant sodium sulfur battery that’s powerful enough to provide energy for the entire town. Not only will the battery serve as a back-up source of power, other utilities can use similar batteries to store energy generated by renewables.

 Big Old Battery, BOB, Presidio, sodium sulfur batteries, battery powers Texas town, Electric Transmission Texas, batteries and renewable power, utilities use batteries, biggest battery in US

BOB, short for “Big-Old Battery,” began charging up this week. The giant sodium sulfur powerhouse, which is literally the size of a house, can store four megawatts of power for up to eight hours. Before BOB came online, a single, 60-year-old transmission line was the only thing connecting Presidio to the grid. The town frequently experienced power outages. BOB serves as a much-needed back-up plan, and it holds enough power to generate electricity for the whole town.

BOB is the first sodium sulfur battery in Texas and the biggest one in existence in the US. Electric Transmission Texas ponied up $25 million to build the battery, and will add $60 million to build a second transmission line by 2012.

Batteries like BOB are useful for towns like Presidio, but they can also be used by utilities themselves. In America’s archaic grid system, electricity generation and usage must occur simultaneously, a huge problem for renewables like wind and solar, which generate power sporadically. Bringing on giant batteries to store power can ensure more renewables are brought online before a smart grid can be put in place.

Via Popular Science

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  1. mdixit February 1, 2012 at 4:25 am

    what is the installation cost of NaS battery ($/MW)?

  2. aktywacjai0 January 16, 2011 at 9:23 pm

    just signed up at and wanna say hi to all the guys/gals of this board!

  3. ajdavies October 19, 2010 at 9:03 am

    Wow-I did my PhD on this battery in the late 1960’s and although we published 5 papers and got it to working well I could not get a job doing battery research(oil rules OK!) – only school teaching was available so I ended up with a career in education. However I glad to see that my research was not wasted. Just shows it doesnt pay to be years ahead of your time.

  4. peterhunt21 October 9, 2010 at 1:29 pm

    These sodium sulfur batteries have a 32 MW capacity and can discharge 4 MW for 8 hours.
    How expensive is it to store that much power in Lead acid batteries?…Has it ever been done?
    How expensive is it to store that much power in Lithium Ion batteries?…Has it ever been done?

    Some people discuss Lithium air batteries which I know companies like IBM are trying to develop to both store energy from renewables and for automotive use in Electric Vehicles where on one charge as many as 400 miles could be driven.

    Some people discuss lithium ion batteries using silicone nanowires for automotive use in electric vehicles where less “precious” metals are used and there is less danger of a fire if an accident were to happen and the lithium was exposed to water.

  5. txaggieengineer June 21, 2010 at 9:03 pm

    In round numbers, the battery & electric power conversion equipment are about $4 million per MW, installed.
    That total project cost of $25 million probably covered a lot more than just the battery.

    NGK (Japan) makes the NAS batteries.
    S&C Electric (Chicago, IL) makes the power conversion equipment in their Franklin, WI facility.

    There have been press releases on a few other NAS battery installations on the AEP system, in the Ohio area.

    “Catching” or “storing” lightning is not something the electric power industry tries to do. They try to divert lightning surge currents to ground, to mitigate the equipment damage that would happen otherwise.

  6. earl88scott June 15, 2010 at 5:46 pm

    How much do the NaSulfur batteries cost and How much for the building and installation. What company built the batteries and what other installations are approved?

  7. kat russell May 16, 2010 at 7:28 pm

    Does this have the capacity to absorb electrical energy from lightening?

  8. TxAggieEngineer May 7, 2010 at 7:32 pm

    1. The battery energy capacity is 32 MWh.

    2. Its power capacity is 4 MW, thus it can provide full power for up to 8 hours. Obviously, if the Presidio load is less, the battery can last longer.

    3. It is rated for a 15 year lifespan of charging and discharging daily, if needed. At end-of-life, the battery modules can be replaced without incurring all the construction costs. Hopefully, better battery technology, and a new transmission line, will have come along by then.

    It can also be used in parallel with the grid supply to store cheaper electricity off-peak and put the power back on the grid on-peak when electricity is higher priced.

    4. NGK has addressed the various safety and end-of-life recycling issues with their design and business plans. They’ve been working on the sodium sulfur battery technology since the ’80s.

    5. Efficiency is approximately 80% round-trip. Lithium Ion batteries have a higher efficiency, but they cost a lot more. Lead-acid has a much lower efficiency and lower energy per cubic foot. Inertial (flywheel) storage has a much lower energy density, but has decent power density, and excels at frequency regulation where it is constantly switching between charging & discharging.

    6. It’s a sad state of affairs when Mexico has a more reliable electricity supply than Texas. Obviously, Presidio is an exceptional case, but still…

  9. joshgoes April 15, 2010 at 10:20 am

    mzedeler: Don’t be so harsh – the author just copy-pasted that portion from Popsci :-) . I think what that mashup of units is supposed to mean is “can PROVIDE four megawatts of power for up to eight hours”, which sounds pretty good to me.

    Also, do we really need FIVE (5) separate links to the same Popsci article? Maybe a wikipedia link with an explanation about how this is a really good application for this type of battery might have helped.

  10. caspianhiro April 8, 2010 at 11:03 am

    Some clarifications for y’all. The Public Utility Commission is the state entity that regulates all utilities (and of course trains!?) in Texas. They also regulate what the power transmission company can charge the power generation company.

    Texas has its own power grid, separate from the East and West power grids.

    Texas lets consumers choose their energy company, but power transmission is still a monopoly. In order to own a transmission monopoly, the company has to provide power distribution to ALL of the residents in its area.

    Presidio needed new power lines at a cost about $60 million, or can use this battery as a stop-gap measure, possibly allowing the utility to *never* have to upgrade the lines. So, spend $25 million now, and then maybe save $60 million later, or spend $60 million that you didn’t budget now. Much easier to defer the decision. Also, the article isn’t clear, but would it have to also upgrade the existing line?

    It’s more complicated that this, but this is a comment in a blog.
    “Power to Choose” explains generation vs distribution…sort of
    Electric Regulatory Council of Texas essentially a state-owned corporation that manages the energy market and Texas energy grid.

  11. Majken April 7, 2010 at 2:51 pm

    You can’t just make up numbers to prove your point has a lot of information about the benefits of these types of batteries as well as the lifespan – 15 years

    Besides that you didn’t factor in the other costs:

    how much do the blackouts cost the community? There’s surely lost business for one, extra maintenance no doubt.
    How much did the alternatives cost? Given the current grid system there aren’t many alternatives. Building a smart grid is certainly going to be a lot more expensive as it has to be done for the whole country.

    Construction costs aren’t the same as operating costs. Will it cost the same amount every time the battery needs to be replaced or is there a first time premium that is offset later.

    Does having the battery allow the town to sell electricity back to the grid? What’s the projected population growth?

    Who’s going to pay? The town is probably going to pay for it through property taxes.

  12. David R. April 7, 2010 at 2:31 pm

    It says the electric company bought it in the article.

    “US. Electric Transmission Texas ponied up $25 million to build the battery, ”


  13. Variable April 7, 2010 at 1:06 pm

    Cost – $25,000,000
    Population: 4,167
    $5999.52 per person.
    I do not know about this kind of battery but a lead-acid lasts 5 years (in my car) so lets use that…
    $6000 over 5 years
    $1200 a year (per resident)
    $100 a month (per resident) House with 4 people $400 a month.
    Sounds like a GREAT investment….. WHO will pay for this? Probably all of U.S.

  14. Moish April 7, 2010 at 10:25 am

    How does the battery compare with inertial storage (flywheels)?
    Safety? (as they say in Texas, “Keep your powder and sodium dry”)

  15. AllenFromTexas April 7, 2010 at 9:30 am

    That solar panel picture ain’t Presidio. Note the hill in the background. And the buildings. Ever been to Presido? This aint’ it.

  16. mzedeler April 7, 2010 at 3:31 am

    “The giant sodium sulfur powerhouse, which is literally the size of a house, can store four megawatts of power for up to eight hours.”

    Sorry, but thats meaningless.

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