Retaking the GMAT with a 720 would not be advisable--no reason why an additional 10 or 20 points would make more than a marginal difference particularly in the Indian applicant pool, where good scores are expected and you certainly can check that box. Plus b--schools love engineers
While they are not generally in the top 10, you might consider schools in Texas due to your energy focus. Fuqua at Duke also has a new energy program, and Fuqua is solidly in the top 10. Your work experience, while briefer than some schools' averages, sounds very robust and also unique. For this reason and also due to the fact you actually lead others at work, I would say it is not at all a negative to have "only" three years. I would definitely go ahead and apply if it makes sense for you to do so in your career plans. Just make sure you can articulate why now is best for you and you will be fine. If there are other schools to which you are attracted in the top tier, I would say go for them as well. I don't see anything on the surface that would keep you from applying to anywhere you feel you have a good fit with the school's curriculum and culture. I particularly like your unique work experience and feel it would help you be remembered--an important feat when applying from India.
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Bryant Michaels
Admissions Consultant