How to use the electricity from a generator in an efficient way

A portable power bank that you can recharge elsewhere if a good idea for four MacBook. If you expect to be living in a place with no power source for a long time. You should probably check into solar, wind or hydro electricity generation. Which would be best would depend on local resources. You will need to study the purchase cost, power conversion requirements, maintenance requirements and expected lifetime of the equipment. For items like a fridge, you will need to have a storage means that is larger than a portable power bank. Care batteries are not appropriate even if they are new. There are appropriately designed lead acid batteries and other alternatives. You will need to determine the voltage level based on available large appliances of the types you want to use. The most economical strategy would probably be to use voltage converters only for the smaller loads.

You should gather information for future load anticipation, available electrical generation equipment, power conversion equipment, energy storage alternatives and charge controllers. Study how all of the components work and how small energy systems are constructed. Then you can plan and design a system to meet your needs efficiently and economically.