Case Study: Tomato farms from water guzzlers to water producers

As I complete my Personal MBA in the Circular Economy, I am exploring and building my inventory of practical ideas that could or have been commercially applied. Ideas that target Circular Systems, Energy, Water, Waste and Wealth – ideas that focus on using the waste of one process as a valuable input to another.

It takes ~210 litres of water to produce 1kg of tomatoes. In my expert opinion of someone that has never farmed, this does not seem like a good return to me.

Vertical farming methods can reduce this to perhaps 10-20 litres consumed per 1kg of tomatoes, the technique below can generate 4 litres of water per 1kg of tomatoes. The circular economy is a game changer.

How – Putting Physics first

By putting physics first, there is another way, a way that you can produce excess water through agriculture.

Using a principle we have all seen evidence of. A cold glass of water, sweats, this is not coming from leakage, it is from the air around it. It is the temperature differential between the air and the glass.

Water condensing

A practical application of this is using a farm near the sea. We know what happens when you drop down 10m below the surface, it gets cooler.

We use two connected pipes circulating from the sea into the ocean. One black, one white, we know the black one will heat up more than the white one. This will result in a difference in density and we create a circular flow, by using the law of communicating vessels.

Once it flows, it keeps on flowing, provided there is a temperature differential. No need for pumping. It is creating its own energy!

As the cold water is going through the land, it is changing the dew point and we have irrigation in an open greenhouse environment, again the temperature differential will cause a flow of air and we are generating water from the environment as the air is replaced. The  humidity levels are controlled by restricting or releasing the flow of the water in the pipes.

In the case study, tanks were set up to capture the excess water and netted 4 litres of water per kg. This changed the farm (and farming) from a net water guzzler, to a net water producer.

Of course this is not limited to tomatoes. The circular economy principles are a game changer.

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