The Floating Dairy Farm

Pictured above is an artist's conception of a proposed dairy farm for Rotterdam, the Netherlands. Beladon, the developer of the project, wants to build a farm on a barge. 40 cows would live on 1,200 square meters on the top floor. They would produce 1,000 liters of milk every day, which whould be pasteurized and turned into yogurt on the bottom floor.
Beladon calls the idea a "closed-loop system." It's a self-sustained ecosystem. Even the cows' urine and manure would be used to nourish the fodder which would grow there, which includes red clover, grass, and alfalfa.
The goal is to make cities like Rotterdam more agriculturally self-sufficient. Unused space on the water would become a contributor to the well-being of the city. The Guardian quotes Johan Bosman, an entrepreneur who works in this industry:

The world will grow, and more and more people will live in delta cities. Expanding cities need unbuilt areas and green space for housing purposes, so there’s less space for traditional food production. The logical consequence is that we will look to the water to produce some of the fresh food.
“In the Netherlands, fresh food is available and we don’t have very large cities, but we have a lot of agricultural and maritime expertise. We are combining these sectors to try to make an innovative circular farm to produce fresh dairy products, and by doing so make the city more resilient.”