If I built greenhouses they would be quite different to what we know already. My greenhouses would be built like pyramids; to allow sunlight to get in fast, from every angle and direction. My greenhouses would not only be on land there would be floating versions and static structures out at sea, possibly even tow-able by ships and tug boats.
If I built greenhouses I’d consider salt water to fresh water conversion systems out in the oceans to top up any water requirements. I’d add reservoir storage tanks at the foot of the pyramid sides to collect rainwater easily directed down the pyramid shape.
If I built greenhouses I’d make them mobile so food could be distributed wherever I wanted whenever I wanted as it continues to grow during shipment maintaining regular supplies and freshness.
If I built greenhouses I might incorporate solar panels or expand the pyramid theme and create separate solar pyramids next to the pyramid greenhouses.
If I built greenhouses I’d work with the planet, harness the elements as best I could and I’d build thousands of them – enough to make a profit and feed the world.