Old Electric-Car Batteries Put Into Service For Home Energy Storage 198
Hugh Pickens writes "Josie Garthwaite writes that old electric car batteries degraded below acceptable performance levels for autos still have enough life to serve the grid for at least ten years with a prototype announced by GM and ABB lashing five Chevy Volt battery packs together in an array with a capacity of 10 kilowatt-hours — enough to provide electricity for three to five average houses for two hours. 'In a car, you want immediate power, and you want a lot of it,' says Alexandra Goodson. 'We're discharging for two hours instead of immediately accelerating. It's not nearly as demanding on the system.'" (Read on, below.)
Pickens continues: "Deployed on the grid, community energy storage devices could help utilities integrate highly variable renewables like solar and wind into the power supply, while absorbing spikes in demand from electric-car charging. 'Wind, it's a nightmare for grid operators to manage,' says Britta Gross, director of global energy systems and infrastructure commercialization for GM. 'It's up, down, it doesn't blow for three days. It's very labor-intensive to manage.' The batteries would allow for storage of power during inexpensive periods for use during expensive peak demand, or help make up for gaps in solar, wind or other renewable power generation. One final advantage of re-using electric car batteries is that the battery — the most expensive part of an electric car — remains an asset beyond its useful life in the vehicle. 'If there is a market in stationary power for spent batteries, consumers could recognize this as an increased resale value at end of life, however small,' says Kevin See."
Re:Doesn't add up (Score:5, Informative)
Your house uses more than 10kw? I really have to ask, what the heck are you doing??
I have a modest 4x2 house, with a stay-at-home wife and 2 kids. Big screen TV, and all the other creature comforts and I wouldn't even come close to use 10Kw.
In this instance I have to say 'you're doing it wrong'.
Re:Doesn't add up (Score:2, Informative)
An 800W microwave, 3kW kettle for heating water, 3kW washing machine, and 3kW electric oven leaves you just enough change from 10kW for your big flatscreen TV. At peak time I would also have the tumble dryer running, my 500W PC running, lighting (only 240W, bargain!).
In total, it's about 14kW at peak usage (thank heavens the heating is natural gas powered, as are the oven jobs and hot water). Heaven forbid if anyone tried to use a hairdryer at that time as well...
Re:Doesn't add up (Score:5, Informative)
Anyone who needs emergency power isn't going to be using the inductive cooktop, air conditioner and three oil column heaters. This keeps the fridge, tv, radio, and microwave going.
In addition, if you are wanting to go solar or off-grid, then power supply is only half of the equation. The other half being how to reduce consumption. For example getting a LED based TV instead of a plasma based one or putting stuff into standby (or off) when not bring used.
As for 10KW per hour, that is huge. What is consuming that much? An industrial level hair dryer?
Re:Sounds like bullshit. (Score:5, Informative)
This is for grid-level storage, not in-your-home backup. Space and weight are a distant concern compared to cost.
There is an important concept called demand (or load) leveling. How much electricity the grid demands changes significantly over the course of the day, so you much design your power plants and infrastructure to handle the peak load. However the peak load is only experienced a small fraction of the time, meaning you are considerably overbuilt for maybe 16 to 18 hours of the day - especially late at night when most people sleep. The problem is so severe that many utility providers offer Time-Of-Use rates where electricity during off-peak hours is considerably cheaper (and on-peak considerably more expensive) to encourage people and businesses to use less during the day and more at night.
Batteries connect to the grid though a charge controlling inverter - a single piece of equipment. During the off-peak hours they absorb excess energy by charging, meaning the generation equipment runs more efficiently and more economically. During peak hours they release the energy decreasing the demand on the system so it doesn't have to be so overbuilt and therefore less expensive to maintain and operate.
The process of shifting load from peak to off-peak is sometimes referred to "filling the bathtub" [youtube.com] and utility providers love it since it makes their lives much easier. Battery storage is a great way to achieve this at the grid level and anyone who manages to develop a cost effective solution stands to make a LOT of money selling and installing such systems.
=Smidge=
Re:Doesn't add up (Score:4, Informative)
Re:Doesn't add up (Score:5, Informative)
Geez. My house never hits 10 kW peak. Period. I suppose if my wife were baking something, we had the dryer on AND I was running the welder we might hit that.
I use a 2.5 kW generator for the house - works great except the electric stove and the dryer. If we are on generator because of a power outage, we can avoid baking, use the propane grill and just air dry clothes. That leaves the computers, lights and miscellaneous bits of civilization to work just spiffily.
I can't even imagine what he uses 10 kW for....
Re:Doesn't add up (Score:5, Informative)
Yo' space ....
I monitor my power consumption using a Current Cost system (don't necessarily suggest this device, it's a bit wonky, but it works). I get 6 kW running the oven AND the dryer. The hot water heater fires a few minutes every hour during the day. I cannot see a sustained 10 kW load. Ever.
YMMV but if you're really pulling down that many amps, either you have a bunch of very, very clean people in your household.
Or you're doing it wrong.
Re:Questions! (Score:4, Informative)
This is a concept study, sponsored in part by GM. The batteries they have are the ones for a Volt, so those are the ones that were used. I'm also going to go out on a limb and guess that they don't have a warehouse full of these setups ready to sell at Home Depot, but that they had some batteries that were used during development of the Volt and have a lot more miles on them then the average consumer-owned car.
This does show what a technical challenge electric car batteries are: these were charged and discharged beyond the point where they could deliver useful, sustained power to a car, but are still more than capable of handling the lower current, long duration needs of a house. If the nuclear industry could figure out a cool application of their discarded (but still quite energetic) fuel, maybe we could get off of coal ...
Re:This will boost the electric car market (Score:4, Informative)
Nuclear designs already exist for spent fuel! (Score:1, Informative)
Fast Breeder Reactors, Molten Salt Reactors. Those technologies burn the "spent" fuel from traditional PWR reactors.
Re:Doesn't add up (Score:4, Informative)
As for 10KW per hour, that is huge. What is consuming that much? An industrial level hair dryer?
It's 10 kilowatt hours not kilowatts per hour. A kilowatt hour is a unit of energy which could supply a 1kW load for 10 hours, or equivalently a 10kW load for one hour, or any other load at power P [kW] for a time t [hours] where t=E/P where E is the energy in kilowatt hours. Power is the rate of consumption of energy, where a watt is 1 joule per second, and energy is what's actually needed to do a given unit of work.
kW/h is basically a nonsense unit which means 10,000 joules per second per hour. This would be a power "acceleration" unit if you actually wanted to use it. Calling kWh kilowatts per hour is a pretty common misunderstanding that you see a lot in the news so as a EE I feel compelled to clarify when possible.
Re:This will boost the electric car market (Score:5, Informative)
That's an interesting solution. A Leaf's battery (24kWh at 400V) will actually power a whole house for a couple of days, but that would require getting direct access to the main battery output to sustain whole-house amperages. What he did was to connect his fridge to a small inverter, which he connected in turn to the Leaf's 12V battery. The 12V battery in a Leaf is pretty much an ordinary car battery (a little smaller than most), whose normal use is to power the interior amenities of the car. Like any other 12V car battery, it would be depleted before too long... but the Leaf automatically recharges the 12V battery from the main battery as needed.