Or it's probably because your scene take 1 hour per frame to render, I'm doing one project that takes it.
Corona is fast, but it can take a bit to render at high quality.
If you don't have money to hire a renderfarm you'll have to render frame by frame, or ask your school for permission to use their computers and ask them to install corona... It's legal. There is no reason to don't do that.
Anyways, you can render 2 frames in your comouter, but if your computer takes 1 hour pero frame, if you render two frames you'll get 2 hours per frame more or less...
The answer is fight for corona in your school renderfarm I think.
I'm sorry I can't help you more, but really, this is render, quality equals time, specially with unbiased or near to unbiased render engines.
Cheers.