Conversion of 11,200 MWh to a XX MW facility
It's actually kind of a fun experimental thought, because I actually don't have any experience with anything of this magnitude (or several orders below it, to be honest.) This is way out of my experience. Which is why it's fun. (I must admit though that I've been involved in developing a product used by power companies in the US and in China for monitoring the oil temperatures at many internal points within large power transformers used for energy distribution. For those engineers out there... consider the difficulty of placing wires and/or anything electronic inside of a \$2500\:\textrm{kVA}\$ power transformer.)



Your specifications:


\$11.2\times 10^9\:\textrm{W-hr}\$ of energy storage capacity.
\$2.8\times 10^9\:\textrm{W}\$ power delivery capacity.
Able to sustain #2 for \$4\:\textrm{hr}\$,
Lithium ion battery storage technology (perhaps Tesla PowerPack)


The above is able to completely replace a 36" natural gas pipeline, where all of the full-up gas capacity of that pipeline is used to generate electricity, for a period of up to four hours.



Tesla's PowerPack specifications are:


Energy Capacity: \$210\times 10^3\:\textrm{W-hr}\$
Power: \$50\times 10^3\:\textrm{W}\$
System Efficiency: 89% round-trip (4 hour system)
Depth of Discharge: 100%
Dimensions: 51.5" x 32.4" x 86", or about \$2.4\:m^3\$
Weight: \$1622\:\textrm{kg}\$


Tesla's Inverter specifications are:


Power: \$50\times 10^3\:\textrm{W}\$
Dimensions: 39.9" x 49.4" x 86.3", or about \$2.8\:m^3\$
Weight: \$1200\:\textrm{kg}\$
(Scalable Inverter Maximum: \$625\times 10^3\:\textrm{VA}\$)




From the above, we can make some deductions.


Tesla's PowerPack modules provide a nifty full-load to full-discharge time of 4.2 hours. Quite convenient. I strongly suspect that Tesla's specifications have informed the situation here.
Your specifications use watts and fail to take into account the difference between watts and volt-amps. Practical systems delivering this kind of power will need to pay very close attention to these differences and size themselves appropriately. They may also require added components to support power-factor adjustments. These cost money, take space, and require support and maintenance.
Tesla's standard inverters can't scale to your needs. They fall short by a factor of almost 20000. You'll need to find out what kind of inverters can be scaled up in order to achieve what you need.
Assuming Tesla's inverters could be scaled up, you'd need 56,000 of them.
You'd also need 56,000 of their PowerPack storage modules.
If everything were stacked side-by-side, with no hallways or room for getting in there and repairing or replacing anything or for dissipation of heat, you'd need almost 300,000 cubic meters of volume to store them. If you avoid stacking them, that's 34 acres -- jammed tight. Clearly, you'd need a LOT more than 34 acres.
None of this deals with the requirements for distribution and support for that distribution from the inverters. Nor does it deal with building space for personnel, their support (food, airconditioning, workspaces, etc.), the storage needed for equipment and parts, shipping docks, roads, etc.


And like I said, you need to isolate these units from each other. You would NOT want the explosive failure of a unit or two to cascade into failures of nearby units.

There are lots of other details. I assumed 100% efficiency above. Tesla claims 89%. Assuming Tesla takes into account all of the final system's losses (which I'm sure their figures don't), you'd need 63000 pairs of modules and not 56000. (I'd say you should tentatively plan on 75000, until you can refine the figure down more precisely.) You also need to work out how to shift loads onto and off of the grid and how to deal with replacing failed distribution components while they are operating. Things fail under heavy load and when they fail, if you must maintain continuous operation, you need to be able to move that load onto another unit (without risking its destruction, too) and isolate the unit you need to replace and bring back on line. In the meantime, the temporarily "overloaded" unit may heat up beyond its specifications. Or if it doesn't, it will certainly age faster than before. So you need to keep track of the rate of aging of all of these components so you can anticipate and avoid, rather than respond to disasters.

And I really have to wonder about a system that only gets used once in a while. If it only gets used during extreme cases of need, odds are that is also exactly when you will find out there are problems. So I'm pretty sure the system needs regular testing and use to maintain it's ability to function in a pinch.

I can only begin to see some of the fun, here. I hope you have a good team on hand.