"Anyhow, I don't know how to give an exact answer, but I don't think the energy required would be significant as compared to the amount of energy needed to split water. "

As I recall, it takes about 4.5 kwh to split a kg of water.
Or 1.6 x 10^7 joules of electrical energy per kg of water.

So for 100,000 kg it's 450,000 kwh.
Or 1.6 x 10^12 Joules

Or if one has a 20 kw solar array, it requires about 2.6 years of electrical power.

{In comparison, the Apollo landers landed with: "Main Engine Propellants: 2,358 kg "
http://www.astronautix.com/craft/apollolm.htm
So, 100 tonnes is equal to the rocket fuel needed for about 42 Ascent LM. Or if you are shipping the rocket fuel or water to Lunar orbit- it could be enough rocket fuel for a dozen or 2 Apollo type missions.}

As I said I don't know the electrical cost to cool 11,112 kg of hydrogen from around 90 K to 20 K. [And a factor in this electrical cost is how quickly you want to do this which could be related to the amount one needs to pressurize your cooling system. Or how big of cooling system one uses. But if one is going cool 11,112 kg of hydrogen every 2.5 years, that is about 12 kg of hydrogen per day.
If you split 5 kg of water per hour for 2.5 years, it totals 109,500 kg. So, about a gallon of water an hour, is about the rate one might get in near term, so something like 10 gallon hour would be quite a different world than are now living in- Mars colonies, etc.]

But for ballpark purposes, if we assume 14,304 joules of electrical power per kg per 1 K, then 70 K for 11,112 kgs it is 1.1 x 10^10 joules or about 1/100th of the energy cost to split the water.