Hi John, If corn is being grown on marginal agricultural land for biofuel production, it should be no problem. But the carbon budget allocation and greenhouse gas contributions needed to produce synfuel need to be accounted for. Algae to biofuel isn’t in competition with corn to biofuel. The products get produced in very different environments.

The food crop land as corn for ethanol is repeating an attack from big oil to kill biofuels.
The Pimentel study, which was funded by oil, was intended from its start to “prove” that biofuels could be killed by propaganda, by publishing a “study” that showed the worst possible assumptions you could make, show that it would be a bad way to get biofuels.
It was roundly and thoroughly attacked and debunked and disproven, yet even among environmentalists, it’s still repeated ad-nauseum as if alcohol biofuels can’t be produced economically.

No one with half a brain and any integrity ever thought of using food crop corn as stock for ethanol biofuels. Sure you could do it as an experiment, but no one who wasn’t trying to attack biofuels ever suggested doing in on industrial scale as if it would be a normal practice.

And so, decades later here we are hearing about it as if it were the only or preferred way.