Hi! I just thought I'd submit my version of this amazing song! This is how we play it at
my church. I'm a Girl (a Soprano, not a Tenor like the song is writing for), so even
though the original key is D, I usually sing it in Bb. I hope you find this helpful! :) 
Pastor Tabitha

Great I Am
Capo 3
G              Am7     D              Gsus
I wanna to be close, close to your side
              Am7        D         Em/G
So heaven is real and death is a lie
               Am7       D     G                 Am7
  D
I wanna hear voices of angels above,  Singing as one

       Em            C
Hallelujah, Holy, Holy
          G          Dsus
God almighty, Great I am
D      Em7               C
Who is worthy, None beside Thee
      G               Dsus   D
God Almighty, Great I Am

//// D  Em7  C ////

G          Am7    D                Gsus
I wanna be near, near to your heart
            Am7     D          Em/G
Loving the world hating the dark
            Am7         D        G             Am7
  D
I wanna see dry bones living again, Singing as one

       Em            C
Hallelujah, Holy, Holy
       G               Dsus
God almighty, Great I am
D      Em7               C
Who is worthy, None beside Thee
          G             Dsus   D
God Almighty, Great I Am

//// D  Em7  C ////
He's the Great I Am Great I Am  (2x)

Em
 The mountains shake before Him , The demons run and flee
C
 At the mention of the name King of Majesty
G
 There is no power in hell or any who can stand
D
 Before the power and the presence of
              Em7                C               G   D
//The Great I am,  The Great I am,  The Great I am    //

(Repeat Chorus up the octave)

       Em            C
Hallelujah, Holy, Holy
       G               Dsus
God almighty, Great I am
D      Em7               C
Who is worthy, None beside Thee
          G             Dsus   D
God Almighty, Great I Am

//// D  Em7  C ////
He's the Great I Am Great I Am  (2x)

(Repeat bridge and Chorus, if you'd like)