Fuel ethanol. Big investor driven industry which managed to get mandates for production in more or less all fuel for personal transport. Production of which is at best energy neutral while at the same time diverting a significant portion of the best land towards nonsense non-energy-production. They know full well that the energy budget for inputs vs outputs is awful, but it's a profitable venture, particularly with high and rising oil prices.

There are plenty of other examples of "greenwashing", but ethanol is perhaps the worst offender in the US.