Part of the deal is that Africa will get a percentage of the output. It's the "what's in it for them" thingy (+jobs) and the electricity can be used for whatever is wanted, e.g. desalinisation. Hopefully by providing electricity rather than money there will be less chance of corruption.

Not much electricity is need for desalination by using the concept given at http://www.seawatergreenhouse.com

BTW--it can also be used to produce FOOD in desert environments.