The goal is indeed to to get the battery cost to $100/kWh. That's the battery cost, not the cost of the energy. So, for example, a battery capable of storing 20 kWh would cost $2,000. The $0.13/kWh that you're quoting is the price of your electricity.
A prime example of the naive faith that technology is infinitely malleable and any miracle is possible if we just put our minds to it.
As James Howard Kunstler says, we have a touching belief that all problems have technological solutions, and we lately have taken to using the words "technology" and "energy" almost interchangeably. It just ain't so. Read his book The Long Emergency.
First - I'd like to applaud DesignNews for providing visibility to the critical need of mass energy storage as a practical enabler of most "renewable" energy sources such as solar and wind power. This is a "dirty little secret" that most green power advocates fail to mention, but the grid can't really acheive over, say, 30% green sources without bumping into this big problem.
By the way - one reason that the US Govt. is heavily promoting electric vehicles (even though the technology isn't really yet ready for mass adoption) is that they have a HOPE that millions of EV's connected to a "smart grid" will actually BECOME the required mass energy storage for a future green energy system. It could happen, but I'm pretty skeptical and think there are better solutions.
I believe that the two most likely practical solutions are: A) a chemical "fuel" that can be synthesized via solar or other energy sources (biofuel or even better - direct solar or electricity synthesized fuel). This fuel can then be "burned" in a rather conventional power plant or even possibly in vehicles or B) direct thermal energy storage as molten salts which buffers power from multiple renewable sources.
It is relatively inexpensive to have huge insulated tanks of molten salt as energy storage. Converting this heat storage is typically done by rather conventional steam turbines. see: http://en.wikipedia.org/wiki/Solar_thermal_energy#Molten_salt_storage . Furthermore, these systems can be designed for long life and minimal maintenance, etc. and don't use toxic and rare chemicals.
The current experimental installations use heliostats ( http://en.wikipedia.org/wiki/Heliostat ), and results look encouraging. However, wind power could also add heat to a storage system using resistive elements (I'm not aware of this being tried). Another great benefit of this approach is that a power plant designed to use molten salts for an energy buffer can easily have a "backup mode" of operation that creates steam using natural gas (or other conventional fuel) and the same turbines / generators. This way, the powerplant can provide reliable 24/7 power even during extended overcast or windless days. This flexibility allows one power plant to provide power instead of requiring two plants (one renewable, one conventional) for guaranteed power.
Hopefully a practical solution can be invented and deployed before a "Mad Max" scenario that will happen if fossil fuels run out before a new solution is in place.
I used x's4 as an average comparing lead/ nicad, NiFe to Lithium present average about in capacity/lb.
In cycle life it's hard to beat NiFE/Edison or Ni-Cad flooded cells which last 50+ yrs. Some NiFe made in 1900/10 for EV's are still going strong!! I have some Nicad battery cells that are 40+ yrs old and still do rated power I abuse in an E bike. But NiFe really needs watering every 4 days and battery self discharges over 10 days. Nicad is much better but still more work than lead has almost 2x's the number of cells at 1.2vdc/cell, lead at 2,2 and lithium about 3.7vdc.
Some lithium if charged correctly and not over discharged like A123 get over 10k cycles. But they likely have an age limit we won't know until they hit it. 7 yrs is mentioned by some makers but no one really knows as they haven't been around long enough to find out. YMMV
Lithium's need very good battery management systems to live and those are still coming up to speed. I'll wait until price drops some more to about $250/kwhr before I switch my EV's over to them as lead does fine and my pack has another 5 yrs in it.
One last thing is battery salepeople are liars. Never ever believe them. Ask but verify anything they say. In hobby EV's we, EVDL list that have been building, driving EV's for 30 yrs, , take every new battery and test it hard both on the bench and on the road, then report to the rest of EVers if it's good enough and if it meets specs. Few do.
In the future li/air and li/sulfur have 10x's present Li cap on the bench. If they can tame them and increase cycle life fossil fuels won't stand a chance. Costs for materials would be about $20/kwhr at that weight!! I believe in a battery only when I can put it in my EV's though as many are vaporware.
The only good point is even lead batteries in a well designed EV or home power RE system can do what we need very cost effectively. For those few times you need more, just fire up a small generator for unlimited range at over 100mpg.
Before I go I always wondered why those up north don't use heating fuel to make electricity first, selling it to pay the cost of the fuel? Power the home, charge the battery for when the heat cycles and supply peak grid power at high profit rates? I can't justify it here in So Fl but up north would be the first thing I'd do before my first winter there.
Sounds to me like you are seriously overcharging your batteries, murdering them. You shouldn't need to water batteries more than 4- 6x's/yr if charged correctly. They only need to be equalized 1/mo to 15vdc. I see at most 1hr/mo doing battery check/watering, washing PV or give the windgen a good look at. Only poor systems need a lot of work.
Most batteries do not die, they are murdered well before their time. You think lead is hard to do, Wait until you get lithium.
One doesn't 'desulfate' lead batteries, they are charged, Pulsing/desulfating scam does little that a 60cycle battery charger doesn't do. Nor do properly cared for batteries sulfate until their 7-9 yrs for golfcart and better lead batteries. By the time they are sulfated, they are already dead so reviving' them only lasts a few weeks at very low capacity.
Any good RE system needs to be automatic tending to itself most of the time on battery charging, grid feed times, etc. It's not that hard to do. Just stop charging when batteries hit 14-15vdc/ 12vdc nom depending on temp, age. The other is cut loads at 10.75vdc to prevent reversing a cell. Done right you'll get 7-8 yrs out of them.
Though for homes, business molten salt of which there are a number like The Zebra Battery allready in the OEM market for vehicles, etc and GE is doing one could be a good market. Backing up the grid is too big a job for batteries.
Charge eff might be good but keeping it hot means you have to really work it to be economic. In EV's their eff dropped badly from such losses if the vehicle didn't work most of the day, or better, 24/7 like delivery or taxi, for which they are great it seems.
I use lead battery storage in my 'off grid' house in Tennessee. Here's the big lead battery problem: The $100 / kwh needs watering, desulfating and equalizing to preserve its promise. Use of hydro-caps lowers watering expense (including labor), but increases the cost. AGM lead-acid batteries reduce much of the above listed limitations, but go for about $175 / kwh. But, here's the big deal breaker... You get about 500 cycles at 50% depth of discharge. That's $0.20 / kwh alone. I look forward to these batteries, and the 57 degree C batteries being promised for 2015 for $250/kwh. The big deal is that they offer thousands of charges without all of the maintenance. Plus charge (coulombic) efficiency is over 99%. This promise then provides storage under $0.02/kwh which makes it a deal changer.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.