For all these days, I have been keeping mum by just looking on the various methods of this system and how does the working goes on. Though I am very keen in starting AP in my home town (INDIA), The only factor which is making me to sit back is Electricity. While working on economics, I found that Electricity is eating my project. 'cause the rates are very high here. So I want you friends to help me out in giving some ideas wherein by using little amount of Electricity, I can kick start this system and equate inputs to that of outputs. Moreover Farmers here do not get Electricity 24/7. They get Electricity only for few hours per day. Also going for alternate source is something like trying to touch the sky for them. Keeping these factors in mind, I am trying to do some thing to help them to adopt this very promising venture. That's the reason I am seeking Help from you friends.
I Think about these issues a lot, as I have a home that is not on the grid, where I would like to try AP gardening, and energy conservation and minimalism is a fine art. I'm just going to brainstorm a bit here and I'm sure others will join in.
In order to have a continuous flow of water and nutrients through your system in intermittent situations, there has to be some sort of storage system that will keep the water flowing, either from a ballast tank (water reservoir raised above the AP system) or from batteries. During the times of electrical excess, you would use a charge pump to fill up the ballast tank at a much higher flow rate than the flow required for the AP units.or charge the batteries at a high rate. During times of electrical drought you would slowly drain the water tank to feed the beds (through gravity) or drain the batteries to run the AP pump. These are issue that any small town (In the United States) has to deal with to maintain water pressure to homes. You would be looking at it from a micro scale perspective, of course.
Maybe this will kick off a dialogue for others to add to.
I apologize if my first response added questions, as what may be common in the US may not apply in India (or other places). Let me add some detail to my thoughts.
A ballast tank (also called a pressure tank) is used to store water and provide water pressure in rural homes that have water supplied only through a private well. Homes in US cities and in the suburbs get their water through underground piping through a water department where the water pressure comes from lakes and reservoirs and water towers that are higher than the homes.
In my mountain home, I have a 500 foot well that has a 1 HP submersible pump at the bottom. Water is pumped into the 60 gallon ballast tank at a rate of 5 gallons per minute until the ballast tank reads a pressure of 70 psi. This normally takes 4-5 minutes to top off. When a faucet is opened, the pressure in the tank lifts the water to the kitchen and baths. At some point when the water in the ballast tank has drained to about 20 psi, the pressure switch turns on the pump and it fills the tank again until it reaches 70 psi again. Throughout the day, the well may only turn on 2-4 times depending on the water usage. That covers the water storage example.
To provide electricity to the pump, I have a 24V photovoltaic array that charges a bank of batteries (electrical storage) throughout the day. I have on yearly average 6 hours of sun per day, but the amount of current that is charging the batteries is only about 1/12 of what the well pump requires, hence the batteries provide the electrical energy for the large demand of the pump, and in between times are filled by the PV's throughout the day. The 24V of the battery is converted to 120VAC by the inverter and then to 240VAC by an auto-transformer (to minimize voltage drop) down to the submersible pump. That covers the electrical storage.
If money is available to buy renewable energy systems than anything is possible, but for poorer regions of the world, this is not a reasonable alternative. Generally, what power you get from the grid, if it is in your local, will always be cheaper than buying a complete micro-grid, The intermittent power problem has to be solved by methods of energy storage, whether electrical, mechanical or by using gravity.
A gravity system using a large reservoir and a controlled flow can be used to feed a series if stepped grow beds and fish tanks and when power is available the reservoir is replenished by a standard AP pump with a flow rate higher than the drain rate down the steppes. Most AP systems have some sort of on-off system anyway, you would just be expanding the water storage for the times when the pump cannot flow (I'm not addressing the dilution of the nutrients because of the extra water).
Through hard labor one could lift the water back up a bucket at a time or by peddling a bicycle connected to a mechanical water pump or a generator to an electrical water pump. I'm too old for such a thing and I don't think you want to do that either. Mechanical or electrical water pumping could also be accomplished using the wind pump (also called a windmill over here) or a small scale wind turbine that you could build. Since you are not powering a whole house this way, the intermittent wind might cover the intermittent electricity you get from the government utility.
In some way or another you have to provide the energy necessary to fill the void. I do not think the ballast tank concept has been considered by the AP community as a way to provide water flow backup during power outages. Rather than using a low wattage pump that has to run continuously, it might be advantageous to use a high wattage pump that can develop the pressure to fill a ballast tank for short periods of time.All the nutrients have to flow through the tank so it becomes an integral part of the AP system.
I hope this didn't confuse you.
Actually many people have talked of using a header tank (ballast tank) for aquaponics. However the realities of needing to have that much extra water in a header tank as well as a sump tank that can handle that much water really tends to put a damper on things. Like say you had a 1000 liter fish tank and 2000 liters worth of total grow bed but you could only depend on 2 hours of reliable water per day. To get a flow rate of 1000 liters per hour through your fish tank you would need about a 24000 liter elevated tank above your fish tank and a 24000 liter sump tank. So for the 2 hours of power per day you pump all the water from the sump tank up to the elevated tank and you have the system set such that the water will flow out of the header tank at about 1000 liters per hour. You would need a pump that could lift 12000 water from the sump tank up to the top of the header tank in an hour and it would run when the power was available. And even with all that, such a system would probably only be able to support about 30-60 fish to grow out depending on the size of the fish. If for some reason the power didn't come on for a day, some one would need to spend much time bucketing water from the sump up to the header tank and they would need to do it faster than 1000 liters per hour or come up with some other manual means of moving the water.
After going through all that, suddenly wicking beds and extensive ponds seem more appropriate.