Biodiesel is not meant to replace all fossil oil and will never do so. But if you were to do so (with current oil sources) it would probably leave you with little agricultural land left.
You could use algal bioreactors instead those dont take up any agricultural land but are very expensive to operate. You would also still need to grow energy crops for the production of alcohol needed for the transesterfication step.
Biodiesel is not meant to replace all fossil oil and will never do so. But if you were to do so (with current oil sources) it would probably leave you with little agricultural land left. You could use algal bioreactors instead those dont take up any agricultural land but are very expensive to operate. You would also still need to grow energy crops for the production of alcohol needed for the transesterfication step.