Question: How do you know/did you decide/create the biosphere of the silo? I don't remember that much detail in the original WOOL series.
Answer: Because I'm a total geek and did an analysis of most of the main factors and filled in the slots much like a real biosphere is designed.
Longer answer: Hugh Howey left a lot of those details vague because it worked with his stories and let our imaginations roam wild. But I'm a scientist by profession in a couple of fields and one of the reasons I was so drawn to the original story back in 2011 was because it left me with so much to think about, figure out and draw for myself. I think that is a natural human reaction and may have played a role in the WOOL plague spread throughout the reading world.
After WOOL 2 and 3, I decided I needed to see how big the WOOL silos really were so I took Juliette's walk as the measure in a huge parking lot and came up with an answer that shocked me. The silos are ginormous. They make the couple of silos I've been in seem like root cellars. Their sheer volume means that they would have to possess a complex biosphere it order to have successive generations of healthy individuals.
And that is basically how I did it. I figured out the required components and then selected plants and animals that could fill those needs but whose own needs could be filled with minimal other inputs.
I get specific questions on Olives and fats a lot. Many people seem to have wondered about that in the first books. Olives are actually pretty easy to grow. I grow Arbequina olives here in Eastern Virginia without a problem. You can restrict their size with pots and their fat is high quality. Ditto with sesame and other seed based fats.
Hope that answers your question! You can ask me more questions using the contact form to the right. Also, if you want me to send you an email when the next book, "Dark Till Dawn" comes out, use that contact form for that too. I'd be happy to. With the holidays coming, it's easy to forget about something you wanted for yourself.