The Three Square Foot Diet - minimal footprint?

I have been working on projects to increase the sustainability for people who choose to do so. It isn't enough to make it possible at great expense, to make it available, or to make affordable. What is necessary is to make it practical, attractive and compelling. Here is a math concept, to come up with minimum numbers. A population of 200 billion could easily be sustained on Earth if we lived at 100 times this number. Establishing an estimate of a minimum is useful for understanding and measurement.
After some debate with a physicist friend, a great deal of personal confusion and much study I found out that hydroponic lighting companies lie to us, with an anthropomorphic lie. Our eyes prefer green light, possibly due to a lot of time spent in a green environment surrounded by plants. Green light is the brightest, and we have the most receptors to green light. Plants have a bias toward red and blue light, building the most receptors to these wavelengths. Blue makes them get taller, red makes them get shorter, squatter and release flowers and fruits. Some require a certain amount of daylight, some can grow 24/7, others can complete all of their life cycles in permanent light but only grow 18-20 hours per day.
If we give these plants the kind of light they prefer best, less electricity is needed to grow them. I'm still experimenting with ratios of red to blue light, and different species, but it is possible to grow strawberries year round with only $2 per year for a few servings per week. I began thinking, "What is the minimum amount of space necessary for someone to live?" The 2002 estimate for the United States was using 24 acres per person, and there only exists 13 acres per person available in the national borders. http://www.sustreport.org/news/footprint2002.htm
How small can it be? Well I studied different means of making food, clothing, shelter, etc. I have studied transportation overhead, and space travel. Space travel is interesting because you only get to use what you take with you. How much do you need to bring for how long? NASA even calculates the cost, weight and space of the replacement light bulbs. One proposal for saving space, and providing necessary systems involved using spirulina as septic treatment and as food. I still don't know much about the former, but for my own health I take spirulina as a treatment for diabetes. Food I do know about.
The medicinal amount of spirulina necessary was rather expensive. If I were to buy a bottle of 180g dry at the store, it would be between $25-33 depending on brand and store. Ordering 5 pound bags was less expensive, at $150-180 per bag. ($139-183/Kg and $66-79/Kg) My best price would still cost me $450 per year at my lowest medicinal dose (20g/day). So, I'm growing my own.
Peak absorbtion matching peak emission LED lighting for growing plants (registered patent pending) would be the most energy efficient way of producing plants. My calculations indicate that it is 20 times more efficient than sunlight, based on growing tests and using commercial quality silicon solar cells (experimental quality solar cells makes it 40x more efficient than sunlight). The balancing complete nutrition, ease of digestion, completeness of digestion, and exponential growth make spirulina platensis the hands down winner. It is also safe to eat in large quantities, which is a good thing. It lacks Vitamin C and a few mineral salts. It is actually a bacteria (and technically not an algae) that makes cell walls using proteins, essential fats, and performs photosynthesis. Spirulina can provide a life support system, waste recycling and food all in one. Adding tomatoes, spinach or seaweed would all be ways of creating a complete nutritional diet. By dry weight, spirulina is 70% protein. Wikipedia and Nutrition Data disagree about vitamin B12, while Natural Ways does an in depth analysis of spirulina. Eating 180g of spirulina per day only yields 280 calories, so wheat, flax or rice should be used to increase calorie intake. Marshall Savage is quoted with much different numbers, and eating only spirulina was suggested.
To produce 180g of spirulina per day, Antenna Publications (link dead) recommended a 4 square meter growing pool, holding 1000 liters. Partial sunlight was recommended to avoid heat and UV, and LEDs produce neither. With 5.5 (North American) solid hours of sunlight per day the population doubles every 2-4 days. We should see greatly increased growth rates under LED lighting at sufficient intensity. The main limitation noted by many commercial and research growers was a lack of CO2 in the water, sodium bicarbonate is used but aerobic bacteria and/or air infusion are possible alternatives. Any closure of systems cycles making a closed ecology is obviously a good way of providing necessary materials, maybe a single organism can supply the necessary CO2. I like the idea of air infusion the best, absorbing instead of releasing greenhouse gases is my preference.
So how do the numbers pan out? What is the minimalist lifestyle? I don't have great numbers for solving carbohydrate production, maybe there is an aerobic bacteria that eats cellulose (like yeast) that could be paired with another algae that uses cellulose for cell walls. Rice production in the US is around 6500 pounds per acre (difficulty on getting data sources that don't remove feedstock from worldbank.org) or about 1.6 pounds per square meter per year, about 1700 calories per pound, or 2730 calories per sq m. Aiming for about 1000 calories from rice (which is a lot of food without processed grains) comes out to 133 sq m of rice per year. That makes the total for food production 4 sq m for nutrition (using sunlight, not high efficiency LED), 133 sq m for carbohydrates. I would need to look again, but I think NASA planned on bringing grains if they grew food on a trip to Mars. In any case, 137 sq m per person is much better than 97,000 sq m per person.
I'm going to grow vegetables, berries, herbs and spirulina and buy my grains. Without dairy, which I may crave less with more spirulina, my food bill may be $5-15/month using 2 shelves and 6 square feet. I normally eat meat and previously suffered trying to be vegetarian, but eating wheat berries and brown rice I just haven't wanted meat. With Earth based cooling, good window based heating, a solar panel, laptop and growing my own nutrition I can produce net positive energy to pay off infrastructure costs. I would still need to buy grains, and insulin.
Right now, lacking real data on several points and just as a guess, I would place the minimalist footprint at around 50 square feet bunkbed style, or 100 square feet living single - plus buying carbohydrates. A good sustainability metric would tell us how long living like that would be necessary to pay back the infrastructure cost of the laptop, solar power system, LEDs for food, etc. Other techniques, like building higher rather than expanding cities, working from home, not needing cars, shared kitchens and other suggestions (flax fiber or corn plastic clothing) would make this minimal number a complete estimate, and not just a place to sleep with food to eat.