This is a student project so the correct unit of energy is a "Library of Congress Stacked with Red Bull Instead of Books."
Now, you may convert that into Joules, if you care to.
I couldn't pass up that challenge...
The Library of Congress has 1,199km of shelf space.
A Red Bull can is 52mm in diameter.
A 250ml Red Bull can contains 481kJ of energy.
Doing the sums, I made the following estimate.
Assuming a single row of cans: 23,057,692 cans, and 1.109x10^13 Joules.
If we have a nominal shelf depth of, say, 250mm - let's call it 5 rows of cans - we get 115,288,461 cans, and 5.545x10^13 Joules.
For comparison, a kiloton of TNT releases 4.184 terajoules, so a Library of Congress of Red Bull contains the equivalent of about 13.25 kilotons of TNT - about 1 Hiroshima Bomb, give or take.