Ask HN: Can a single city house sustainably produce its own food, energy?

Let's start with caloric requirements. I found http://www.waldeneffect.org/blog/Calories_per_acre_for_vario... which I'll take at face value. An acre irrigated and planted with potatoes supplies 17.8 million dietary calories per acre. To get a round number, assume yearly food needs of 1 million calories (2739 dietarycalories/day, or about 11500kJ). You'll need about 227m2 under cultivation. My house is on a .17 acre (690m2) lot, so I have room even without worrying about the area covered by the house itself. (this is an average-to-large size for my American city)

"Irrigation" means lots of water. I found http://www.cals.uidaho.edu/edcomm/pdf/bul/bul0789.pdf figure 6 showing peak yield at 23 in/year (60cm). Happily, my home town gets 31 inches of rain per year. Collecting and storing it will be a challenge; if I wanted to store a year's supply it would be around 136000 liters. Additionally, water is hard to store here over the winter because of below-freezing temperatures, but you may need to in order to have the water early in the season when your plants are starting to grow.

So, I'll go with yes to part of the question: on a good year weather-wise with good technologies, you can grow enough potatoes to fill your caloric requirements. With somewhat more area you can probably grow more diverse (but less energy-dense) foods that can meet other dietary needs.

.. the main item I realize this is ignoring is fertilizer, but with excess electricity you can use the Haber process to generate all the ammonia you need. So the main external input is solar energy and water. If you needed to for the purposes of your question, you could add enough technology so that you could reclaim substantially all of the water, too.