Post by Deleted on Jan 14, 2016 4:22:00 GMT
In response to the comment on TSI about growing a garden to supply food, and deal with waste, i daydreamed and ran some numbers.
The following is based on a 5 gallon bucket being enough to grown veggies sufficient for one person per day (or 7 buckets providing assorted veggies for 7 days). Furthermore, i am assuming a 5 gallon bucket holds a full cubic foot of dirt and weighs 90 lbs, altho it cannot possibly hold that much, and the dirt is certain to weigh less with the addition of fluffy compost and leaves and etc.. I also did not count the weight of the irrigation water in the bucket, because that will vary widely from planting day to end of harvest, and it will be appropriate to the crop.
A 7.6ft diameter air bubble can be made in steel for under $500. It will be lightweight, not strong, and need to be placed under wave forces. It will displace 180 cubic feet of water, or 5.5 tons.
A garden made of a grid of 5 gallon buckets, 20 x 20 buckets being 20 x 20 feet, made of 400 buckets, with 90 lbs in each bucket, totalling 36,000 lbs. 18 tons. Sounds heavy.
Now if one 7.6ft dia air bubble is placed under each corner of the garden, each bubble capable of holding 5.5 tons, adds up to 22 tons, while the garden is spec'ed at "only" 18 tons.
So...
4 bubbles at a full $500 each is $2000.
400 buckets of dirt at $4 each is $1600
There's misc things i do not have a price for in front of me, like the required deck and the legs down to the floaties. But lets take the total of what i do have prices for and add 50%: $5400.
Yeas, sounds spendy, $5400 (cost to build), $15 per day per person for veggies.
Lets cheat and say one person isn't going to eat a whole head of lettuce per day, or 8 beefsteak tomatoes per day, or 6 lbs of brussel sprouts, or not 10 carrots. Lets say we can use science to make each bucket produce those quantities reliably: a head of lettuce, or 8 tomatoes, or similar quantities. Lets say that much can feed 4 people, along with their ocean harvest of fish, plankton, shrimp, clams, or crabs. And their land-bought grains (pasta, rice, barley, quina, bread, etc). Think of it this way: 4 people, 4 buckets, #1 bucket has a head of lettuce, #2 is 8 large tomatoes, #2 is 4 carrots and 4 radishes, #3 is a trellis for string beans, #4 is some kind of pepper. The 4 people can make a salad each day, perhaps a bowl of soup too, for 4 days, from those 4 buckets. The contents of the 4 buckets can vary, and some plants like cherry tomatoes and brussel sprouts and beans will re-set with a new harvest next week.
Then the cost is $3.75 per day per person. It's the cost of 2 cans of Campbells soup at the grocery store. It's also picked-that-day fresh.
But that is $3.75 a day for the food until the farm is paid for. A year. Thereafter it's whatever the paint and zincs cost. If the garden metals (or geopoly/basalt) lasts for 10 years, the food cost might be amortised down to 37 CENTS per day per person. Somewhere between the garden providing food for one person or 4 people, it's going to be cheaper over 5 years, or 10 years, than buying from the grocery store on land. It's likely going to be cheaper than the fuel to get to land and back, or the marina slip rental while you are at the grocery store. And lets not forget that the $5400 cost outlined might be spread over the year, because just like you wouldn't plant the entire year's food all at once, you don't need to buy all the dirt or all the floatie all at once. In 4 months, you will be at the point of harvesting the first bucket you planted, and within a week, re-planting it, not re-buying it. You can make decisions on how to continue, change bucket sizes, diversify what you plant, maybe group things, change the layout, maybe open a diner-marina.
And i didn't figure the math on the dirt buckets get replanted throughout the year, which at least doubles down on their payback rate. (By the way, if dirt isn't your thing, use clay pebbles, or 100% aquaponics water, it's approximately the same overall costs and weights for the purposes of this discussion.)
And, however you chose to process your personal "waste" (methane, compost, heat sterilization, dessication, etc), the garden exists partly so you have a place to put that material when done with it. Ditto water flushed gradually every day from the aquaponics. Or perhaps the clothes washer rinse cycle.
Plus, the floating garden is 20 tons of passive stabilization for your seastead, and a place to stretch your legs, and attach solar panels to the perimeter of, live underneath of, whatever. If one of my 20x20ft decks becomes a food garden, with a shady spot in the middle where i can take an afternoon siesta, it will make me smile.
For those of you building 60x60 floats, 400 sq feet of garden is a 7ft strip running down the sunny side of the deck.
The following is based on a 5 gallon bucket being enough to grown veggies sufficient for one person per day (or 7 buckets providing assorted veggies for 7 days). Furthermore, i am assuming a 5 gallon bucket holds a full cubic foot of dirt and weighs 90 lbs, altho it cannot possibly hold that much, and the dirt is certain to weigh less with the addition of fluffy compost and leaves and etc.. I also did not count the weight of the irrigation water in the bucket, because that will vary widely from planting day to end of harvest, and it will be appropriate to the crop.
A 7.6ft diameter air bubble can be made in steel for under $500. It will be lightweight, not strong, and need to be placed under wave forces. It will displace 180 cubic feet of water, or 5.5 tons.
A garden made of a grid of 5 gallon buckets, 20 x 20 buckets being 20 x 20 feet, made of 400 buckets, with 90 lbs in each bucket, totalling 36,000 lbs. 18 tons. Sounds heavy.
Now if one 7.6ft dia air bubble is placed under each corner of the garden, each bubble capable of holding 5.5 tons, adds up to 22 tons, while the garden is spec'ed at "only" 18 tons.
So...
4 bubbles at a full $500 each is $2000.
400 buckets of dirt at $4 each is $1600
There's misc things i do not have a price for in front of me, like the required deck and the legs down to the floaties. But lets take the total of what i do have prices for and add 50%: $5400.
Yeas, sounds spendy, $5400 (cost to build), $15 per day per person for veggies.
Lets cheat and say one person isn't going to eat a whole head of lettuce per day, or 8 beefsteak tomatoes per day, or 6 lbs of brussel sprouts, or not 10 carrots. Lets say we can use science to make each bucket produce those quantities reliably: a head of lettuce, or 8 tomatoes, or similar quantities. Lets say that much can feed 4 people, along with their ocean harvest of fish, plankton, shrimp, clams, or crabs. And their land-bought grains (pasta, rice, barley, quina, bread, etc). Think of it this way: 4 people, 4 buckets, #1 bucket has a head of lettuce, #2 is 8 large tomatoes, #2 is 4 carrots and 4 radishes, #3 is a trellis for string beans, #4 is some kind of pepper. The 4 people can make a salad each day, perhaps a bowl of soup too, for 4 days, from those 4 buckets. The contents of the 4 buckets can vary, and some plants like cherry tomatoes and brussel sprouts and beans will re-set with a new harvest next week.
Then the cost is $3.75 per day per person. It's the cost of 2 cans of Campbells soup at the grocery store. It's also picked-that-day fresh.
But that is $3.75 a day for the food until the farm is paid for. A year. Thereafter it's whatever the paint and zincs cost. If the garden metals (or geopoly/basalt) lasts for 10 years, the food cost might be amortised down to 37 CENTS per day per person. Somewhere between the garden providing food for one person or 4 people, it's going to be cheaper over 5 years, or 10 years, than buying from the grocery store on land. It's likely going to be cheaper than the fuel to get to land and back, or the marina slip rental while you are at the grocery store. And lets not forget that the $5400 cost outlined might be spread over the year, because just like you wouldn't plant the entire year's food all at once, you don't need to buy all the dirt or all the floatie all at once. In 4 months, you will be at the point of harvesting the first bucket you planted, and within a week, re-planting it, not re-buying it. You can make decisions on how to continue, change bucket sizes, diversify what you plant, maybe group things, change the layout, maybe open a diner-marina.
And i didn't figure the math on the dirt buckets get replanted throughout the year, which at least doubles down on their payback rate. (By the way, if dirt isn't your thing, use clay pebbles, or 100% aquaponics water, it's approximately the same overall costs and weights for the purposes of this discussion.)
And, however you chose to process your personal "waste" (methane, compost, heat sterilization, dessication, etc), the garden exists partly so you have a place to put that material when done with it. Ditto water flushed gradually every day from the aquaponics. Or perhaps the clothes washer rinse cycle.
Plus, the floating garden is 20 tons of passive stabilization for your seastead, and a place to stretch your legs, and attach solar panels to the perimeter of, live underneath of, whatever. If one of my 20x20ft decks becomes a food garden, with a shady spot in the middle where i can take an afternoon siesta, it will make me smile.
For those of you building 60x60 floats, 400 sq feet of garden is a 7ft strip running down the sunny side of the deck.