self sufficient life

Small scale aquaponics setup

The nice thing about aquaponics is that it is very scalable and can be set up almost anywhere. If you want to try out aquaponics you can set up a small system to grow herbs in your home. All you need is a small fish tank and a container that can be used as a grow bed. The fish in the tank will fertilize the water with their excrements and the growing plants use these nutrients to grow while cleaning the water.

In a small setup you can locate the grow bed above the fish tank. The grow bed can be filled with lightweight expanded clay aggregate or gravel. A water pump on a timer will fill the grow bed with water and small holes in the bottom of the grow bed let the water flow back into the aquarium. The holes have to be sized to let less water pass through them than the pump delivers to the grow bed. This way the grow bed will fill up while the pump is running. Once the pump shuts off, the grow bed will empty out into the aquarium.

A system like this is called flood and drain and makes the plants grow nicely. In the flood stage the plant can take up water and nutrients and in the drain stage the plants roots have access to oxygen. You can place your setup by a window or, if you don’t have a suitable spot that receives enough light, you can add some lights.

(sketchup model by: Dave)

Heat and power, power and heat

In Europe, Canada and the US, the power companies are required to buy back any excess energy you create. The rates, at which they buy back the energy, depends on a few things and the rules are different in each country and state. You can get detailed information on this subject from your utility company.

Solar energy, for instance, will be paid at a higher rate than power generated with a diesel generator because it is obviously much cleaner energy. In Europe you will also get a better rate if you burn vegetable oil instead of diesel, but you will have to show proof of the origin of your oil, so waste vegetable oil collected from restaurants will not get you the higher rate, although the collected oil will be cheaper than buying new vegetable oil, possibly still making it an interesting alternative on the bottom line.

The amount of energy you can sell back also differs from each power company to the next. While some will buy back as much as you can generate, others will only buy back as much power as you buy from them, effectively leaving your power meter at the zero mark.

Since we are currently looking for a new house, I don’t know which power company we will be dealing with. Assuming, for now, that I can only sell back the amount of electricity that I use, generating our own power will not bring in any money. After working out the fuel usage for the generator and assuming that I have to buy vegetable oil to run the generator, plus the generators initial purchase price and ongoing maintenance, the bottom line is that the power from the utility company will cost about the same or maybe even a little less.

However, the electricity is not the only thing I will be generating. A big part of the energy will be lost as heat. Lost if you don’t catch it, that is! Running the engines cooling water through a heat exchanger in the central heating system will have a positive effect on the total fuel consumption of the central heating.

The whole thing can also be turned around: so, instead of running an engine to cover your power needs and use the excess heat to complement your central heating system, you could also have the engine running to generate the heat to warm your water and house, while running a generator head along side to create electricity while you are heating. Sure, ultimately we are talking about the same system, that generates heat and power, but the sizing of each system would be different.

How our system will be sizes isn’t decided yet. We will first have to find a suitable house. Depending on the age and condition of the central heating system, we will then go one way or the other.

Aquaponics

My aquariums have a healthy balance of fish and plants. The water is crystal clear and the plants are thriving. I don’t have to do any water changes to keep all levels in the optimum range, the only thing I have to do is top up the water every other week to compensate for evaporation. A well balanced system like this is easy to create and maintain in an aquarium. It takes some experimenting, but once you get the hang of it the maintenance is next to nothing and you can just sit back and enjoy watching the fish.

Intensive fish farming is a different ball game. If you want to make a profit you have to put a lot more fish in your water. The water gets polluted by the excrements produced by the fish, making the water toxic for them. Bacteria that live in a biological filter can convert the highly toxic ammonia into nitrite and nitrite into nitrate. High concentrations of nitrate are still bad for your fish, but they are an excellent nutrition for plants!

You could use the nitrate rich water to fertilize the soil in your vegetable garden and replenish the fish tank with clean water. This would however require a lot of fresh water and a big part of the nitrates would sink deep into the soil, beyond the reach of your plants roots.

The solution here would be hydroponics. In a hydroponics system you grow plants in water instead of soil. The water in a hydroponics setup is enriched with nutrients that the plant roots normally extract from the earth. Small crops like salad and herbs can be grown on a raft that floats on the water and has holes in it for the roots to reach the nutrient rich water. Bigger crops like tomato plants need some coarse gravel or rock wool for support. This grow medium is located in a tub that is flooded with the nutrient enriched water. After the growing plants have extracted the nutrients from the water it has to be enriched again.

Hook the fish farm up to the hydroponics and you have an aquaponics system. The fish provide fertilizer for the plants and the plants clean the water for the fish. The balance in an aquaponics system is much like in my aquariums but both the fish and plant density are much higher. As long as you make sure that this balance is maintained, you can make the aquaponics system as big or as small as you want, ranging from one small fish and one plant to a pond with thousands of fish and an acre sized greenhouse.

A big commercial system isn’t for everyone, but you can have a small aquaponics system in your garden or kitchen made out of items you probably already have laying in your garage or shed. Put a little work into it and you can enjoy home grown fresh herbs and vegetables, without the pesticides!

Looking for information on the subject, I stumbled upon the Backyard Aquaponics Forum, which turned out to be a very friendly community of people with a great deal of knowledge and experience in this field.

Fish farming

I have enjoyed keeping fish for a long time. Looking for something that could make some money in the winter time, when crops don’t grow on the land, fish farming sounds like a good option. There are several species of fish that could be breed economically in our central European region. I would probably keep carp, tench and zander.

Fish farming can be done in two ways: extensive (pond) or intensive (closed-circulation) Extensive aquaculture requires very big ponds that are lightly stocked. You will need about 15 square meters (160 square feet) of pond surface area for each carp. The total water volume doesn’t really matter since the food supply in the pond is following the natural food chain, starting with the algae growing in the sunlight hitting the pond, making the surface area of the pond the limiting factor for how much fish you can grow.

With intensive aquaculture you can keep as many fish as you can fit in your body of water, as long as you make sure that the water is clean and that there is enough oxygen and food available for the fish. To keep the water clean and oxygenated a good filtering system is needed and a set of pumps to move the water through the filters.

Since a patch of land that is big enough for extensive fish farming would just cost too much, I will work with a closed-circulation system. I will have to look into the total cost of different systems. The cheapest option would probably be digging a big pond, but the fish production would be limited in the winter time. A more profitable system would consist of indoor ponds, making it possible to achieve maximum growth year round.

How much land can feed a family?

After reading about people using several acres of land to be self-sufficient I started wondering how practical it would be where we live. A little more research on the subject lead me to a great article by Greenspree, which takes a detailed look at how much food a family needs and the yields per acre for different types of crops.

The bottom line of the article is that about a quarter of an acre, which is roughly 1000 square meters, can provide most of the vegetable needs for a family of four. Agric says that only about half of that area is needed to be self-sufficient, which sounds realistic, because you can plant different crops on the same patch of land at different times of the year.

The Crop Yield Verification sheet used for the calculations by Greenspree contains a big list of different fruits and vegetables that you can grow and their yield per acre. What I found interesting is the relatively high yield of apples and pears and when planted in the middle of a nice patch of grass where the kids can play, they don’t take up any of the space of your vegetable garden. The only problem with fruit trees is that they need quite a few years of growing before they produce food, so these should not be taken into account when figuring out what we can grow.

I have put 1000 square meters for growing crops on my list of requirements. This should be able to provide my family year round with vegetables and leave some extras that can be sold on the farmers market to bring in some cash to buy things that are not practical to grow on a small scale.