Re: energy storage, oof, yeah, at 146.5 MJ / gallon for diesel fuel, and 10 gallons / hour, 12 hours of fuel holds 4884 kWh of energy. Assuming you need a similarly sized battery, you're looking at 60 Tesla (car) batteries. That will weigh approximately 36 tons and cost about $700,000, based on Tesla's 141$/kWh stated cost.
Hmmm, I'm guessing you can't put more than 8-10 tons of battery on a tractor that size (the John Deere 7250, which is actually 13g/hr, weighs 13 tons) so you're limited to maybe 3 hours or so of power between charges or swapping out your batteries. For that much battery, you're looking at maybe $175,000; the John Deere 7250 retailed for ~$230,000. Assuming your batteries are swappable and fast-chargeable, you'd need at least two batteries. (Heck, it's a tractor, maybe it can be on some sort of wagon you tow behind, which would make swapping a snap.)
Putting it together, I think we might actually be approaching viability for electric tractors. If you can actually fit 8-10 tons of battery into a 13 ton tractor and build the rest of the tractor for $55,000, you could build a tractor comparable to the John Deere 7250 that would run for about 3 hours; that's not a bad amount of time to run between swapping out the batteries, but you'd need at least another $175,000 battery to swap out, which already makes you ~twice as expensive as a regular tractor. You would probably need the battery weight and cost to drop by half again before you could get a tractor that would run all day (with a battery swap) and not cost more than a conventional tractor.
Well, if you're towing something behind you on a tractor, you can't use the power take-off anymore, which kind of ruins the point of the tractor for most uses.
You might be able to set up a convoluted system where you have the power cells being dragged behind whatever equipment you're using, assuming you can get enough tires underneath to not undo whatever work you're doing to begin with (first we plow the field, then we pack it down tight!)
But then you also can't use the ~10 tons to provide extra weight on your wheels.
It just feels like you ought to be able to store your batteries in a way which makes swapping them/carting them around easier, if you don't need to have a sleek aerodynamic package that fits on a highway. Actually requiring a crane to swap your batteries adds a lot of overhead, along with room for comic fuckups.