Ann: Gas Sales Agreement to Deliver Power to Eureka Gold Mine, page-108

Not quite as easy as that to convert Diesel generators to CNG.. You need to condense the gas down to a liquid, change fuel pumps & injectors, Add lube to the CNG flow, Refrigeration to condense the gas.
It would work out cheaper to sell existing Diesel set and installing new Gen Sets or install Gas turbine Gen Sets.

If the infrastructure is designed and built around offtakes of the Cabora Bassa project and that with success in our drilling campaigns and and multiple production wells there could be no reason why we could not build a generation infrastructure to supply most of or all of Zim"s requirements and export on the SAPP.