Comment by xnull2guest | Hacker News Reader

Comment by xnull2guest | Hacker News Reader

The problem with this is that the grove will not be able to grow enough to sustain (or come close to sustaining) even a single person. By the very, very most optimistic calculations (best recorded growth in tropical greenhouses) you need at a minimum 300 sq ft of space. But more realistically a 1000 sq ft or more are required to sustain a person.

Then there's actually a ton of labor that goes into growing, picking and correcting the plants. Just ask someone who has worked in a garden, tried aquaponics or grown something hydroponically (weed or otherwise). Automation can still only do so much, especially when it isn't at scale.

This relegates their grove to growing single types of plants very well. Growing fruits requires more light than vegetables, but either way you're looking at at least 40 watts per sq ft of space, usually much more (especially since the light needs to penetrate down through the leaves). For even a small setup of 8 sq ft you're looking at something that pulls 4 kwh of electricity a day at minimum (around a half a dollar). Taking between 3 and 6 months to grow some fruits you're look at a minimum of $75 a yield but probably closer to $400-$500 or even more after you calculate the costs of HVAC (big), water pumping and heating/cooling costs and chemicals (which are on the order of a dollar-per-day expensive). And then a lot of the equipment needs to be replaced and is very expensive, especially if you are running lights. Most of those have a shelf life of around a half year, unless you do LEDs which are extremely expensive investments. Of course this needs to be compared to the yield but generally economies of scale, even organic ones, can produce goods much cheaper. And hydro isn't organic...

The reason hydroponics is associated with weed is because you need to grow something that costs more than your inputs.

With traditional technology you need more than 300square foot to support a single person.

But with hydroponic + vertical farming you could need a lot less (±1meter square).

You can with today technology have a production (versus traditional farming) gain of : - 2x improvement by controlling light cycle to trick plant into growing faster - 4x improvement by controlling season (in temperate climate you can just growth 6 months a year) - 5x for hydroponic vs. soil growing. - 15x production by stacking cultivation box in top of one other.

Using this technique you should be able to attain 600x production over traditional farming for the same surface.

Some are already doing it for cabbage in Japan (see Mirai : http://www.fieldrobotics.org/~ssingh/VF/Challenges_in_Vertic..., who sell itself to GE and who produce 5000kg of cabbage / day in a 1200m2 farm).

What make this technology viable now is the availability of cheap and energy efficient LEDs.

It certainly isn't enough to sustain a single person but it's still nice to supplement your diet with fresh herbs and greens.

It's not viable for growing fruit or vegetables, though. That just doesn't make any sense economically.

We have a very similar hydroponic garden at our office and it's not a lot of work to maintain it. Basically adding a few buckets of water every week is enough. Every few months it needs an hour of maintenance, though (planting new seedlings or cuttings).

There are also organic hydroponic nutrients available. A dollar per day for nutrients is way too much if you're growing salad. Your basic plant food from the supermarket is a few bucks and lasts for months. You can spend as much money on expensive weed nutrients but that isn't necessary.

Hydroponics are used a lot outside of growing weed. Commercial production of herbs, salads and other greens is almost exclusively done with hydroponics, at least here in northern Europe, where light and heat are at a premium half of the year. Maintaining a greenhouse is expensive so maximizing the production per area per time is required for a viable commercial operation.

It's kinda the rich man's version of growing cress and bean-sprouts in a plastic tray on the counter top.

Perhaps what one needs to do is use the hydroponics to grow an environment for insects to live in and feed off the insects instead?

Ah, ah, ah. Plant basement full of grass and put a goat down there. Low maintenance and deliciousness to be had.

Plant roof with grass and save the floor space for something more interesting?

Feed black soldier flies with compostable waste. Use the grubs to feed fish. The fish waste can feed the plants.

Running an aquaponic system is not easy. We have been running one for a year now inside our house under growlights (as an experiment - no way it is economical). a lot is automated with the arduino, but if my wife was not a microbiologist we would have failed totally. Super interesting however.

Having had experience with hydroponic horticulture, I believe you are correct. Successful hydroponic farming is much harder than it seems it would be.

The amount of light energy required to grow plants properly is very large and hard to supply with artificial light sources. Fruiting plants, like tomatoes, have much higher requirements than leafy crops, like lettuce. Lamps are rather inefficient converting electricity into light.

A 1000 Watt metal halide or high-pressure Na lamp is barely adequate to cover a square meter (if the only light source). Calculate the energy cost of running it 16hr/day for a month and it gives new respect for Mother Nature.

Another headache is plant nutrition. Vegetables grow fast and suck nutrients out of their environment at an alarming rate. There are many systems but the short version is reusing nutrient fluids requires constant chemical monitoring to assure proper pH, mineral content. Automated equipment is out of the question, and a home farmer very likely won't have the knowledge and lab equipment to do it optimally by hand.

There are a whole bunch of other constraints, but the above is enough said. Doing experiments is fun, but apartment-scale production of edibles is definitely no more than a pipe dream.

> A 1000 Watt metal halide or high-pressure Na lamp is barely adequate to cover a square meter (if the only light source).

1000 Watts of metal halide or HPNa? Per square meter? That's huge! You don't need anywhere near that kind of figures for growing salad in your kitchen. If you're working in a commercial gardening operation, then it's a different deal. But then you're either growing weed and/or have a huge area so the W/m^2 figure goes down.

A single fluorescent tube in addition to natural light and your usual kitchen lighting goes a long way.

Most plants are not very sensitive to pH figures nor do they suck up nutrients like crazy. Automated pH and EC measurement would be nice, though. Even better if this garden could automatically add in nutrients and acid if necessary.

Lessons from growing weed are not necessarily valid for food production.

we have been running an indoor aquaponic system as an expriment for a year now and you are right, it is a pipe dream mostly. Lots of fun to be had, but its not a cheap hobby.

Won't we eventually have rooftop solar and domestic batteries that mean that power costs (heating and air cycling, for example) are no longer as much of an issue?

I don't care about organic. I'd be happy to see contained growing that means I'm not losing large amounts of my plants to slugs/snails and caterpillars as I am now. Also the extreme heat in Australian summers troubles my garden too.

Batteries really suck; it's only when you compare the energy density to actual fuels that you realize quite how bad they are. And the energy efficiency of collecting sunlight, turning it into electricity and then back again is likely to remain poor; you're looking at what, 20% at best from solar panels? (and that's after a lot of work has gone into optimizing them). And at absolute best with optimized LEDs you're looking at 30% on the lighting side, for a combined efficiency of 6%. You might remember that a few years ago there was a big environmentalist fuss about light pipes - weird as they are, they can do much much better than solar-powered lighting if they're practical for the building in question.

Using photovoltaics to grow plants seems a little weird.

Definitely. The only instance I can think of would be if you were at a high latitude and wanted lots of light in the winter. Some sort of solar concentrator mirror seems more practical though.

Blue and red light are best for photosynthesis, so if efficiencies are/were high enough, it could make sense to build a roof with solar panels over your plants, and then use red and blue LEDs for lighting the plants.

Google "blue light in greenhouses" for research in that area; an image search gives several examples. And yes, they do look weird, for example the alien world on page 3 in http://www.lemnislighting.com/pdf/65259%20Lemnis%20Folder%20...

Couldn't you use a coloured "light pipe" instead (http://en.wikipedia.org/wiki/Light_tube)?

> unless you do LEDs which are extremely expensive investments

Not sure it's that expensive. DIY solutions are very affordable and I believe LEDs are getting cheaper and cheaper. They don't consume much energy and you can select their frequencies to approach an optimal spectrum for your plants.

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