There's one being set up in Manchester - see http://alphafarm.org/ or Google "Alpha Farm Project".
The concept is a little like a terrestrial version of the space-travelling bio-domes in the 1972 sci-fi film "Silent Running" where the remnants of Earth's flora are sent off into space in self-sufficient domes. It's intended that they return to Earth when the conditions become conducive to sustaining plant life again. I found the film profoundly sad on one level - the very storyline indicated that Earth had become inhospitable to plant life, so it's starting point was already some sort of nightmare scenario. It also highlighted how space must be a very lonely place, and not one we can inhabit easily, even if we overcome the technical challenges. On another level, it was fascinating in its portrayal of self-sufficiency. Total recycling, including air, water and nutrients. Energy from the Sun (for the plants' photosynthesis) - and probably some also from a sort of nuclear propulsion drive. Each dome was a small-scale version of the Earth's ecosystem, with all the main ingredients that make the Earth 'work' and sustain life. Surely, it must be vastly easier to achieve this sort of approach, in real life, on the surface of the Earth rather than in space?