An agricultural land can support energy crops yield to produce $7000$ $\text{L}$ of bioethanol per hectare and energy content of bioethanol is $21 \mathrm{MJ} / \mathrm{L}$. This bioethanol displaces fossil-based petrol.
The $\mathrm{CO}_{2}$ offset potential of land used for growing energy crops as a bioethanol feedstock is $\_\_\_\_$ $\times 10^{6} \mathrm{~g}$ of $\mathrm{CO}_{2}$ /hectare (rounded off to one decimal place).
Consider $\mathrm{CO}_{2}$ footprints of $10$ g and $80$ g of $\mathrm{CO}_{2}$ per $\text{MJ}$ for bioethanol and petrol, respectively.
