An excellent question. Let's put it this way, each has it's advantage. It depends what your goals are. Whatever they are, your emphasis should match your goals.
Now of course, you can change your goals too
. My tendency would be to advise you to go with Oil and Gas (which if I understand correctly, is the majority of your work( while having one essay revolving around renewable energies to show broadness of scope, not forgetting that it all should fit into one goal. The main thing is to use your best stories to draw a clear line from your past to your future. Choose whatever will help you do that best.
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