over 5 years ago by fsteckel
Which problem are you trying to solve?
Many people don’t have enough water to sustain health or irrigate land to grow food. They need companies selling them
water for high prices. Wells are overused, thus sinking the ground-water-level.
How are you going to solve the problem?
By developing simply produced solar water-desalination systems, easily affordable in the 3rd world. Instructions via
online videos and in local schools for students to build and spread the word.
What is the impact of your project?
It impacts all 4 categories:
Ecological: People can grow their own food.
Education: Local schools build and
Health: People get enough water and food.
Refugees: Refugees might not need refuge.
How can the project be manufactured in the OpenLab?
Prototype needs sheet-metal cutting and drilling. 3D printing is used for producing bending-rigs for tubes.
Tube-fittings are 3D-printed or lathed. Experience of other makers can flow into the design.
Describe your project in detail
The desalination system consists of two main assemblies. One (thermal) Solar Collector Array (SCA) and the Multiple
Effect Desalination (MED) unit.
The SCA consists of several solar panels. These are made of sheet metal plates painted
black on the front side. Two sheets are separated by aluminium profiles. The back and the sides are thermally insulated
using cork. 3D-Printed fittings for garden hoses (i.e. Gardena) are integrated into the panels. Water flows through
these cheap units absorbing the heat of sunlight.
The MED unit consists of discrete stages (called ‘effects’). In
the first effect, the heat of the SCA is used to evaporate sea water under a light vacuum (~0.4-0.6 bar to lower the
boiling temperature of the water). The water vapour is guided through tubes that are routed inside the second effect.
Inside these tubes the water vapour condenses into fresh water, releasing its latent evaporation heat into the second
effect where more sea water is thus heated. It evaporates, producing water vapour in the second effect that flows into
the third effect, and so on. To increase the salt-water’s surface area and promote heat exchange from the tubes into
the salt water, shredded aluminium foil is integrated into the effects.
The condensed fresh water is sucked out of the
tubes using cheap vacuum pumps. The enriched salt water that remains in the effects is also sucked out after a while and
needs to be collected and put back into the sea.
The MED unit is built in a similar way as the solar panels: Using
sheet metal and aluminium profiles. Its geometry is slimmer as the unit needs to withstand the negative vacuum pressure.
The effects are located next to each other.
The general design principles of this system are:
1. To use the cheapest
possible raw materials, e.g. sheet metal or aluminium foil, that are abundant even in the poorest of regions.
source very cheap components. Due to recent upswings in personal international trade, this is now possible for private
persons. E.g. the vacuum pumps that can be obtained for very little money from China.
3. To make the units buildable
with general available tooling. Should there be special tooling necessary, we will need to source cheap tools to provide
with the unit.
4. To make the units easily repairable. By providing the full design documents to the end users and
providing educational videos how to build/ maintain the units, end users will be empowered to take care of their systems
5. To make the units fool proof using modern open-source control logics, e.g. Arduino/ Raspberry Pi.
one of the project's central goals to include local schools, where the pupils will build these units for their
school. This will generate a deep understanding for the systems. Schools will then be able to provide courses for
interested farmers to educate the community on how to build/ take care of the system. This will provide an excellent
option for sponsorship for EU Governments or even private persons to sponsor schools with such a system or providing
micro-credits to farmers.
For more details watch the video presentation at:
That is an awesome project and idea... looking forward to hear more of it!
Are you very familiar with the
technology? Do you have some numbers (How long does it take to make a bottle of drinkable water? How many energy/hours
of sun is needed?)
Thanks. I did some conservative calculations. From these, at least a m³ of water should come from the energy
of four solar Panels (each 1m²) in the south african regions (when sun is shining). As these calculations are designed
for the industrial scale applications, it remains to be seen, how well the small system will perform thermodynamically.
But that is why I calculated quite conservatively. Even half of that amount would not be very bad.
Thank you for your comment! Can you please be more specific! I am not sure if I understand it
Of course a final version v1.0 that is provided to be made by local schools needs to be rugged and stable. It
needs to be able to withstand operation for an extended amount of time before maintenance is necessary. This will be one
of the design-issues to be addressed, once a first prototype is operational.
If by environmental conditions you mean
climate: This system is of course limited to certain geographical areas. A lot of sunlight is essential for the system
to be effective and productive. Also access to contaminated or salty water is necessary. In general this system is best
suited for the sub-/ tropical arid regions near the oceans, e.g. Southern Africa, many Saharan, Arab or Persian regions
or even Australia and Chile.
with 1 m². (http://www.pm.ruhr-uni-bochum.de/pm2003/msg00338.htm) I think it really depends on the region, as you
stated. Perhaps these links may be interesting for you
How did you
choose the materials? Did you test the materials or thought of other materials (e.g. natural fiber) instead of aluminium
foil as the production of aluminium foil takes much energy?
genial el proyecto necesitamos agua también en América
which will find investors and supporters because the cost of application at the level of countries is high and its
greatest benefit is the application at the broad level
Sí, América del Sur / América Latina es también un área posible de beneficio. ¡Gracias por tu
I agree. Once the project is ready for its first trials in the real-world, it will be a
challenge to spread the word. That is why I want to go via schools and ministries. One hope is to not only drive the
project further via the make-a-difference campaign, but also to get in contact with people with experience in social
projects, e.g. from ministries.
Thank you very much for your contributions. This project from Uni Bochum is
very interesting. One reason, why I’m hopeful to get more water from the system is, because it is utilizing a
different process (Multiple Effect Destillation) than the Uni Bochum’s. They saturate ambient air with water moisture
and in the next chamber let it condense. This process is simpler than MED but its capacity is limited. I am hoping that
with using MED, the appliance will be more effective (it transports pure water vapor in a vacuum and recuperates the
latent evaporation heat).
One thing regarding the 4m²: That is only for the heat generation. I will also require some
electrical current for the vacuum pumps which can either come from an electrical power grid or from solar panels. My
estimation is that the required electrical power is less than 100W.