Largest Sodium Sulfur Battery Powers a Texas Town 301
separsons writes "The largest sodium sulfur battery in America, nicknamed 'BOB,' can provide enough electricity to power all of Presidio, Texas. Until now, the small town relied on a single 60-year-old transmission line to connect it to the grid, so the community frequently experienced power outages. BOB, which stands for 'Big-Old Battery,' began charging earlier this week. The house-sized battery can deliver four megawatts of power for up to eight hours. Utilities are looking into similar batteries to store power from solar and wind so that renewables can come online before the country implements a smart grid system."
from the article (Score:5, Informative)
the battery would cost 25M, while a second transmission line would cost 60M. o_O
Re:Four megawatts of power for up to eight hours? (Score:4, Informative)
A watt is a unit of power not energy, that'd be 115 gigajoules (or 32 MWh if you're lazy)
Game of telephone (Score:5, Informative)
It's amazing the game of telephone that happens when blogs steal news stories from blogs that steal news stories from blogs.
Inhabitat: "Electric Transmission Texas ponied up $25 million to build the battery, and will add $60 million to build a second transmission line by 2012."
PopSci: "Electric Transmission Texas helped put the battery project together for around $25 million. But the utility has also agreed to build a second 60-mile transmission line to Presidio for about $44 million by 2012."
NPR: "The other solution for this town would be to build a second line, and that line would cost somewhere in the range of $40 to $50 million. And so a battery project in the $25 million range looks pretty attractive."
They all agree the battery costs $25mill, 2/3 agree that the 2nd transmission line will be built in 2012, and none of them agree on the price of the 2nd line.
Energy not Power (Score:5, Informative)
so it holds 32MW
No - it can hold 32MWh (=115.2GJ). Batteries hold energy not power. Since power is energy per unit time you have to multiply it by a time to get energy.
Leaky battery (Score:5, Informative)
"The house-sized battery can hold four megawatts of power for up to eight hours."
"Power" is not "held." Power is delivered. Energy is held. The unit of energy is joule.
NPR Link (Score:5, Informative)
Re:Game of telephone (Score:5, Informative)
Not to detract at all from your point, however there's something worth pointing out I learned while listening to NPR.
This particular city has a contract with a Mexican power company, to provide backup power during the all-too frequent times the lone cable to the US power is broken. However 'some time' is required to switch the city from US to the Mexican power grid. The purpose of this battery is to make the switch from US to Mexican power seamless to the end-user. Therefore, 8hrs is plenty of time for the battery power to last.
Perhaps the battery buys the town time in more ways than one. Now the town is less reliant on someone building out that spare US transmission line for awhile longer. And I'm sure that price varies on which year the 2ns US power line is built.
Re:from the article (Score:5, Informative)
Do you have a reference to the fact that the battery needs to run at 350C?
You could start with Wikipedia: http://en.wikipedia.org/wiki/Sodium-sulfur_battery [wikipedia.org]
It seems a bit impractical to heat a house-sized building that much, especially when you have lost power.
Good insulation, and you don't heat the building, you heat the guts of the battery. Also, the lost energy is likely heating the battery.
I'm guessing a 4MW generator would take a couple of minutes, maybe 10s of minutes, to spin up to capacity.
Not the ones I've seen. (Hospital and nuke reactor backup.)
Re:Energy not Power and Batter Life (Score:5, Informative)
Re:That's a great price! (Score:5, Informative)
*According to wikipedia [wikipedia.org], they need to run even hotter, 300-350 degree celsius
Re:BOBs are probably safer underground (Score:3, Informative)
It runs on molten sodium. Cool is the one thing you don't ever want the battery to get.
Re:from the article (Score:5, Informative)
Reportedly many communities in Alaska are serviced by power generated by massive diesel generators.
Well of course they are. Diesel is the default conservative power source for remote communities in Australia but photovoltaics are moving in. Solar power may not work as well in Alaska but wind power may do the job instead. Combine that with a BoB and you have a good reliable power supply.
Re:from the article (Score:3, Informative)
Never mind that you would have to store an explosive material.
Not that liquid sodium is that much better, mind you
Re:Tensile strength and inertia (Score:3, Informative)
I found an online calculator and apparently the energy squares with either the diameter OR the speed. The only linear input is mass.
So let's try this: A 100-meter wide flywheel, weighing 10 metric tons, spinning at 1hz, gets you 68 kWh, or double that if you move the mass to the outside (which I presume you would for something that big). Now that's probably light for something so big, so at 100 metric tons you could get up to 1.36 MWh.
This battery has 32 MWh.
You would need to spin it 5 times faster (300rpm) to get that kind of energy. That's frighteningly fast for a ferris wheel. Also it would need some serious electromagnets and one hell of a support structure that's also frictionless.
No matter how you slice it, flywheels are all about linear momentum. They're either big or they're fast and it's hard to both.
Re:from the article (Score:3, Informative)
Not the ones I've seen. (Hospital and nuke reactor backup.)
Ever see them try to spin up a 1 MW class diesel locomotive engine in winter? Its not pretty in the best of conditions, even worse if everyone's stressed out. There's a reason they don't shut off diesel loco engines in the winter. And even in TX it does get cold on occasion.
I was told in a tour that the nuke backup engines go full power in much less than 10s, but, they keep the coolant and engine block heated to operating temp 24x7 with electrical heaters, they have bizarre oil systems that are kept pumping 24x7 yet somehow don't hydrolock the pistons, they have onsite 24x7 maintenance crews, and still they occasionally break so they need multiple ones for true redundancy. I was told the only real delay in starting is something about needing to stabilize the airflow in the intake and exhaust before throwing a huge load on, something about air tanks, pneumatic starters. and how they vent. Obviously this was more than a decade ago, after 9/11 they absolutely JUMPED at the chance to get rid of tours. I was told that they have the cleanest engine oil in the state, actually cleaner than fresh in the can, because they pump it continuously thru filters 24x7.
A battery is a lot simpler, if it will switch over at all, it'll do so in a couple milliseconds, and there's not much maintenance possible, so not much to schedule and pay for.
Re:from the article (Score:4, Informative)
Re:Question: how much energy did it take to make i (Score:4, Informative)
As you can see, the estimates vary widely, there's a lot of guesswork involved in making these estimates. Overall the renewables don't fare that badly, especially wind and hydroelectricity.
In case you were wondering, here's [world-nuclear.org] the CO2 emissions:
So yes, even with all the intensive energy requirements for renewables, they still are better than fossil fuels. The problems with widespread use of renewables are political (i.e. Republicans and conservatives don't like them), require intensive upfront capital costs, and infrastructural (the power grid is not designed to carry power where likely wind generation sites are).
Re:from the article (Score:4, Informative)
Re:from the article (Score:5, Informative)
Ever see them try to spin up a 1 MW class diesel locomotive engine in winter? ... I was told in a tour that the nuke backup engines go full power in much less than 10s, but, they keep the coolant and engine block heated to operating temp 24x7 with electrical heaters, they have bizarre oil systems that are kept pumping 24x7 yet somehow don't hydrolock the pistons, they have onsite 24x7 maintenance crews, and still they occasionally break so they need multiple ones for true redundancy.
I've worked with diesel generators from 1MW up to the size this town would need, that were primarily emergency generators for a nuclear plant, and they were only run for testing, drills and the occasional power loss. They needed a small (like tens of kW tops) set of heaters to keep them warm even in the coldest weather, and there were maybe two 24-7 guys whose responsibility was to go check readings once an hour on multiple generators (and in the non-nuclear world you could easily replace those two guys with some sensors, a computer, a phone line, and an on-call mechanic). I don't remember there being bizarre oil systems, and the oil didn't run 24/7, because it was very quiet when they weren't running.
They really just weren't a big hassle in the big scheme of things. You have to do maintenance on them at regular intervals, but you have to do that to any complex machine, like, say, a town-load-sized battery + inverter installation. Disclaimer: I've never worked with a 4MW UPS, but I don't think it's going to be maintenance-free.
Re:Large inverter to go with the battery? (Score:3, Informative)
One word: IGBT
http://en.wikipedia.org/wiki/Insulated-gate_bipolar_transistor
It's a lump of silicon about as big as a car battery, easily handles 5MW, and has revolutionised the connection of solar/wind/wave energy to grid.
Equipment costing hundreds OR thousands dollars now replaces what used to cost hundreds OF thousands, so connecting the battery to the grid is probably one of the easiest and cheapest problems to solve.
Re:from the article (Score:3, Informative)
A giant AC-DC inverter would work, but where are you going to find such a thing that can handle 4 MW?
Static Inverter Plant [wikipedia.org]
They're used for high voltage DC transmission systems. Actually, they're probably overkill for a 4 MW supply as many plants have been built to handle hundreds of MW each.
Re:from the article (Score:1, Informative)
Well, if oil runs out, the worst option for eletricity generation will be a diesel generator.
Why not? Really, give a reason for one not being able to do that. EROEI is ok, minerals are ok once you adopt a (more expensive) process of refining that uses eletricity instead of oil, mining is ok, transportation is ok. You'll need some bio oils for lubrification, plastics and rubber, but everything quite on the realm of the possible.
Uh. Bio-diesel will still be around long after all the oil is gone, there will still be synthetic oils. It's also those gasser engines that will be useless when all the oil is burned up. Old Rudolf Diesel designed his engine to run on peanut oil. And exclaimed that one day we would be using them as such but they will also work on dirty dino-oil.
Diesel Engines Will Be Around For A Long Time, And Are Much More Efficient Then The Gas-Hybrid and Propane Alternatives.
Why does slashdot alway bash diesel technology?
Re:Leaky battery (Score:3, Informative)
I can't recall ever seeing a battery rated in Joules. Small batteries are rated in both volts and mAh. The voltage times the amperage tells you how much power it can put out. The power times the duration tells you how much energy it can deliver.
Rather than stating that the battery can "hold 4 megawatts of power for up to 8 hours", the article should perhaps have stated that the battery can "deliver four megawatts of power for up to 8 hours", as is stated in the /. summary. From this you could derive that it holds about 115 GJ.
For comparison, I have a laptop battery in front of me rated at 11.1V, 7800mAh. It would take approx. 369,600 of these batteries to store 115 GJ.