We hear in the news that many people in countries that have currency issues are starting to trade in BTC - for example, Venezula.

My friend asked me what about in regions where they lose electricity, how would they trade with BTC?

For example Puerto Rico is right now devastated by the hurricane, and many parts of its region don't have electricity.  A lot of people need to buy food and even fresh water.

Is there a way to still trade with BTC in such situations?  

Can P2P trade still occur despite having any connection to the greater block-chain network?  Keep in mind that it's easy to charge mobile phone so they have access to wallet apps, but probably not the Internet.

I don't know too much about mobile data networks, but I doubt one's 4G/LTE data plan would work in such situations.  I assume that data would have to be relayed to a tower/dish before it's sent to satellites.  Am I correct?