Finally! The complete guide of the Dew Greenhouse Project is ready.
From the time that I published my first sketch about the self-watering greenhouse project, I was inspired by many existing projects such as the OPUR dew collectors, the fog catchers of Warka water, Fogquest, as well as Groasis which is a self-watering plant pot that harvests dew to irrigate the trees. They all contribute into solving water issues in the arid areas and countless communities have benefited from these low-tech and low-cost technological solutions.
There are few other high technologies which condense water from thin air and they require solar panels to empower the dehumidifiers to extract the water from the air. These technologies come at a high cost and due to that, local communities cannot afford to maintain them.
The concept of the dew greenhouse captured a lot of feedback. We have also received many e-mails from people asking questions concerning the steps of building the greenhouse. At the time we could not provide specific answers as we did not yet have a prototype and was not convinced by the efficiency of the pyramid shaped greenhouse. Again the challenge was finding the perfect combination between cost and efficiency.
Why a greenhouse?
In August 2014, I was volunteering in an eco-village. For almost two months in the summer season we grew cucumbers, tomatoes and other crops inside highly humid greenhouses. Continuous ventilation in a greenhouse is necessary in order to cool down the environment by circulating in fresh air and pushing away the warm humid air. Excess humidity is a health hazard: dew can form on the foliage of the food crops as a result of rapid decrease in temperature at night, creating fungal diseases.
So the reason why I chose to research and learn more about greenhouses was because of the high presence of humidity, which was a challenge for other technologies, and I wanted to find a simple solution to these challenges. The dew formation in the arid climate is seasonal and does not always form due to low relative humidity levels.
Our first campaign via Indiegogo in 2015 raised around 8000$ from friends, family and supporters. It enabled us to build our mini institute which provided training in composting, earth bag building, water conservation practices and bio-diversity. The goal was to link students in the Agriculture Faculty from the University of Gondar with the small-holder farmers.
Prototyping the greenhouse was part of our original plan, however, the design was incomplete and it was difficult to implement a new technology that hasn't been researched well in terms of cost, design and efficiency.
Unfortunately, after our program gained momentum, the formation of a new university administration that aligned itself with industrial farming ended up dismissing our efforts and our presence in the university campus was also denied. Due to this situation, a visa renewal was also not granted.
The first prototype 1.0
In November 2017, with the help of a friend, the idea of the self-watering greenhouse had evolved and we were curious to test it.
We created a mini greenhouse with a double roof, which was the first prototype worth building. At the same time we investigated whether the system works without harming the crops and losing the humidity caused by the transpiration/ evaporation from the soil and plants.
For such a small test the results were remarkable. Our goal was to calculate the amount of water that can be potentially collected from the roof of the greenhouse, and to observe whether condensation would appear even if it is dry outside.
Usually, dew appears on the side that is exposed to the external environment, such as the experiments made by OPUR organization. They used hydrophilic films and were able to collect water from the early morning dew, but because the relative humidity is not constantly high in the arid region, greenhouses could be a promising solution. In a poorly ventilated greenhouse, condensation will appear from the lower side of the plastic film that is exposed to the internal environment of the greenhouse. The result of dripping water will prone crops to disease.
The double roof model was supposed to compress the humidity between the two layer rooftops, but the majority of the condensed water drops evaporated during the following day. Insulating the roof will block most of the sunlight that enters the greenhouse.
While the double roof wasn't yet an ideal model, it helped us calculate how much water can a greenhouse collect per square meter from condensation: It was almost half a litre. We believe this amount could increase if we plant crops with a higher transpiration. The first prototype inspired the next model [prototype 2.0] which copies the same v-shaped roof of the first prototype. But instead, the roof becomes an extension in form of an insulated box and can be applied to any existing greenhouse model. In this way, the cost decreases, as there's no need to construct a whole new greenhouse but simply connect the exhaust fans to the insulated box which will do the job100%.
It is without a doubt that commercial greenhouses will only use high tech machines, such as large dehumidifiers that can absorb a lot of humidity. Yet, the amount of energy and cost can only be afforded by big agri-tech companies.
For smallholder farmers it is very difficult to afford these dehumidifiers, so as an alternative low-cost solution that consumes almost no energy compared to dehumidifiers, the amount of the condensed water from a simple radiative cooling power can make a big difference!
Many would argue that greenhouses are unnecessary, but open-field agriculture in hot arid areas is low yielding and risk prone. Adoption of greenhouse technology can improve yield and productivity of scarce water.
At last, I have made all the necessary drawings needed for anyone to start building. You can find them on our new website www.rootsupsolutions.org as we have deleted our old website www.roots-up.org. Go to the Learning Topics and choose - The Dew Greenhouse Project.
We are confident that many of you can improve the system by providing more site details and also have the ability to train others to do so. Today, we are opening this organization to the public. Roots Up Solutions is about experimenting and sharing the knowledge with others.
I have also shared another topic about the basic steps to fight climate change through supporting and investing with smallholder farmers.
Follow the link for more details:
https://www.rootsupsolutions.org/copy-of-empowering-smallholder-farm
