# Energy cycle centered around methane production / consumption

Many car manufacturers have developed projects for hydrogen cars but I've always been wondering why they put so much effort into hydrogen, as it is hard to store, and fuel-cells use to restitute energy back are based on rare-earth-metal not suitable to produce many cars for everyone.

Nature mainly store energy with carbon, I'm not a chemist but is it that hard or not yet enough economically viable for not seing rising projects around simple hydrocarbure synthesis. Easy to store, easy to consume, but maybe hard to produce, right ?

Production : $$\ce{CO_2 + 2H_2O}$$ (+ Renewable Energy Source) $$\ce{-> CH_4 + 2O_2}$$

Consumption : $$\ce{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}$$ (+ Energy To Use)

Could even $$\ce{CO_2}$$ be simply captured from air with limewater in such cycle ?

Sorry if my question may seems too simplistic, but I'd really like to handle (in simple terms) what are the economic/technical constraints to elaborate such apparently simple round-trip.

• The economic barrier to this approach is the current situation of cheaply available methane via mining (natural gas wells) compared to the cost of synthesizing methane from carbon dioxide and water. – airhuff Jan 10 '17 at 19:52
• Hum ... I quite envisage that economic barrier is still higher than technical one :/ – CitizenInsane Jan 11 '17 at 7:36
• Carbon sequestration may be easier growing corn, feeding chickens and using their excrement to produce biogas. No need for any new technology. – Rodrigo de Azevedo Apr 13 at 19:14