Biogas can do it

NATURALLY BIOGAS

Biogas has been around forever. Any natural material on earth is decomposed by microorganisms at the end of its life, resulting in biogas.
In a biogas plant, this natural process is harnessed. In the main component of the plant, the digester, millions of microorganisms thrive and brake down the supplied substrates—organic waste, manure, or energy crops. The resulting biogas is captured in the gas tight storage above the digester and channeled from there.

Biogas consists of 50 to 65 percent combustible methane (CH4), 35 to 50 percent carbon dioxide (CO2), as well as nitrogen, water, oxygen, and some trace amounts of hydrogen sulfide. It can be used to generate electricity, heat, or fuel.
The leftover digestate can be effectively used as fertilizer in agriculture or horticulture, supporting the growth of new energy crops.

A perfect cycle.