To whom it may concern,
Capitalize every word when you do the opening salutation.
I have an idea for improving the way this sentence feels on the reader's mind:
I have no hesitation in writing this letter
of recommendation for to recommend X
to accompany his application for the Master program in Energy...
Always try to improve writing by saying what you have to say in fewer words. Good writing hits hard with no more words than necessary. Hah, it's funny that I just redundantly wrote 2 sentences to express that same idea about not using more words than necessary. : ) And now I'm digressing, which is another way more words than necessary are used. I'm a blatant hypocrite. But still, consider doing this:
I have had the pleasure of getting to know X over the course of the last t For the past two years, I have observed him to be
I found in him a keen student of the subject of Electrotechnical Engineering.
X, is a reliable and disciplined person. --- Don't put a comma after the name.
Hmm... this is all too vague and abstract. Can you add some more specific examples? One great writing strategy is: "Show, don't tell..."