# Is the hydrogenation of carbon dioxide to methane a solution or a problem?

The hydrogenation of $\ce{CO2}$ to $\ce{CH4}$ is thermodynamically a favored reaction at ambient to moderately high temperatures.

$$\ce{CO2 + 4H2 <=> CH4 + 2H2O (g)}\qquad G^\circ_{\pu{298K}}= \pu{-27 kcal/mol}$$

$\ce{CH4}$ (natural gas) is an excellent fuel for a variety of applications. It is also a good C1 feedstock for manufacturing other chemicals. This reaction can be used to recycle $\ce{CO2}$ and reduce its emission to the atmosphere.

So, why not use $\ce{H2}$ from photoelectrolysis of water to produce $\ce{CH4}$ and achieve multiple goals of storing solar energy, creating a useful feedstock and recycle atmospheric $\ce{CO2}$?

I said, $\ce{CH4}$ is 30 times worse than $\ce{CO2}$ to the atmosphere and also the photoelectrolysis of $\ce{H2}$ is still an expensive method that requires more time to achieve maturity.

Is it right? the other student on the panel said my answer was too vague.

$\ce{H2O + CH4 -> CO + 3H2}$