This is how the castle will grow much of its food:
A super-intensive low footprint portable farm, with no soil, no chemicals, low water requirements, and an aquarium attached that you fish out of too. Now of course it costs quite a bit to buy the starter kit from these guys, $7500 for the basic kit, but I think you could do it yourself for about 2-3k, even with high quality pumps (never skimp on pumps!) and a few mistakes along the way. You'd make your money back in two or three years, pretty easily.
I want to figure out a way to add a saltwater tank to the mix... perhaps we can grow seeweed and use it to feed the freshwater fish or something, anyway 'cause then we could have that tank of jellyfish in the castle and it would also serve a purpose in our food cycle.
Which by they way that's the whole trick of aquaponics: it's a circle, not a chain. It doesn't just go one way. Lawn care in America really freaks me out when I think about it: we plant this crop, grass, in the ground, and we water it and fertilize it, so it grows, and then we cut it, and throw away the clippings, until we've depleted the soil so badly that we have to fertilize it again.... But the grass is a really good sport about all this! It just keeps growing! It just grows back again and again and again. When you think about how unconnected lawns are to the natural order, to the circle, it's kindof mind boggling that it's so mainstream, and that it works as well as it does.
But that's the beauty of plants, after all. "Turning light into food for over 2 billion years," as they say. Erg, I gotta get my store back up....