Wednesday, August 17, 2011

Growing Food At Home: Urban Farming with the Malthus

We need fresh vegetables and fruits.  I don't think there is anyone that would argue that statement.  The problem: it's cheaper to buy processed foods than to buy fresh vegetables.  And the quality of those fresh vegetables are generally, well, not so good.  I don't mean rotten by any means, but they are generally tasteless.  And if you don't have any flavor in your food, you don't want to eat it.  That's the concern facing my family, and may other families in the world today.  How can you afford to eat right, and enjoy it?  

The best answer is to grow your own food.  Of course that means having land, a good source of water, time to let it grow, etc.  It's a long and laborious process to grow food traditionally, and you end up with a single harvest that then needs to be used up quickly or it's lost.  This seasonality of vegetables makes having fresh vegetables all year round just as frustrating.  And then there is the land issue.  Even if most families in the average suburban land plot plowed under all their grass and grew vegetables, they wouldn't have enough for all the family.  No, they would need to expand in a big way to get the food they need, even for one meal per person per day.  And this is exactly what urban farming is all about:  providing a way to grow food in an urban area (including high-rises), either as a supplement to the current diet or complete subsistence farming.  

Urban farming has become a very popular topic, it seems.  More people are predicting food shortages, uncontrollable pricing, and, well, end of the world type situations where you defend your warehouse full of Twinkies with your rifle.  Personally I'm of the opinion that urban farming is something that anyone who is interested in having more control over their food bill and food source should take seriously.  Nothing tastes better than food you grow yourself, mostly because it doesn't have to be picked green for better shipping.  Real food, like ripe tomatoes right off the garden vine, has a special flavor that you can't get anywhere else.  

But what if you don't have the space for a garden, as I found I didn't after my son ripped up my seedling tomatoes and herbs in the back.  How do you grow what you need in little space?  And what about meat, assuming you are not a vegetarian/vegan? Clearly you need to either move to a better location with more room to produce your food, or come up with a way to grow your food in a high enough density to provide the food you need.  As most people do not want to, or cannot move, the best option is to find a way to produce your food in high density. 

One way to do that, and one that I find very promising, is aquaponics.  For aquaponics to work, you need a tank full of fish (and by extension, their waste) to feed your plants, which in turn filter out the waste to keep the fish water clean.  The fish benefit from the clean water provided by the plants (and if you have herbivorous fish like tilapia, food as well), while the plants benefit from the fertilizer provided by the fish. If produced in a high enough quantity, you can produce enough food for at least one meal per person in the house.  The thing is, how do you do it, and how efficient is the process?  

Well, one design group has built and tested a configuration using commonly found products.  Conceptual Devices has built the Malthus, a system to grow within an enclosed space food enough for one meal per day. The concept is pretty clear, and they have a working model in Zurich.  It's a great idea, and I think it's something that could easily be deployed in any household.  Because it's all spaced vertically, the footprint is low.  Salad plants, at least any that are not head lettuces, will continue to throw up new leaves as you cut, making them regular producers.  Plants like Tomatoes and Cucumbers will continue to produce if they don't have a frost, though you will need to pollenate them by hand (or with a small paint brush).  

The fish, well, that's another story.  The fish in the picture are tropical fish that are not, generally, suited for eating.  Tilapia, on the other hand, would make for great eating, provided they can be produced in a high enough quantity, which this setup doesn't seem to make possible.  No, if you want to have daily fish on the menu, you will need a bigger setup.  Still, fish every once in a while isn't bad, and makes a great supplement to the salad being produced.

Anyway, it's definitely a good idea, and one that is worth exploring.  So, first off..  how much will this thing cost?  Cost of materials would vary, depending on what you have on hand.  I might do an estimate on that, though for a one-time expense, as long as other costs (like electricity) can be covered, the materials cost could be recovered over time.  So the repetitive cost of electricity becomes a concern.  How much power does this use up?  

   The first thing I checked out was the LED lights.  I found some LED strips at that are about that right size, and pulled the details. Each strip runs at 225 mA (milliamps), or 0.2 Amps at 12 volts.  That means for a set of four lights as outlined by the plans, you are looking at roughly 10.8 Watts of power being used every hour it is being used.  You would probably want to time it to run about 16 hours, giving the plants 8 hours of rest, so that would be 172.8 Watt-hours, or 0.1728 kWh per day.

   Next, I checked out the water pump.  For a good one, you need a pond pump for dirty water applications.  I found a small one (shouldn't need a large one) at  It's rated at 5 Watts per hour. 

   The Air Pump depends on the size of the tank you get.  The one listed in the parts for this setup is a 400 Liter tank, which is about a 100 Gallon tank in the US.  You need a fairly large air pump, and the one I found that fits it is the Tetra Whisper 100, which runs on 4.8 Watts her hour. 

As everything else is just a one-time purchase (barring any issues), these are your repeating costs of running the setup.  All total, you are looking at almost 21 additional watts per hour for the Malthus.  You would be running the pumps for 24 hours a day each at almost 5 Watts, making it about 240 Watt-hours, or 0.24 kWh a day.  Add them together and you get 0.4128 kWh a day, at the price of 5.9536 cents a day.  Monthly that would be about $1.50 more for a daily meal.  Is it worth it?  That's up to you.  

So, it's an interesting concept, and one worth exploring more.  Perhaps one day I'll get a chance to build something like this, just to see how it would work.  It would be nice to have a fresh meal of veggies every day, just waiting for me.  

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