The CO2 output by animals is much lower compared to...

It's one of the biggest leading CO2 producers regardless, bigger than all transport combined, and more-so it takes HUGE amounts of water. That's why you keep hearing about droughts if you want to know the truth. Look into our problems finding clean drinking water, that's because of animal agriculture.

A better solution would be to find more environmental friendly sources to generate energy.

We already have them but because people still vote for devilish corporate capitalists they refuse to adopt it as they profit more by selling garbage like oil.

is thinking they actually make a difference.
As an individual you may not, but every fifty people who switch in your area does reduce demand and thus you will make a small impact.
To say it's not meaningful enough is no different from saying giving your leftover food (or a bagel shops leftover food) to a homeless person won't stop poverty so you should throw it away. It's choosing to do bad/evil/etc simply because...well no reason really :)