1. Universität Hohenheim, Institute of Agricultural ... · Universität Hohenheim, Institute of Agricultural Engineering, Tropics/Subtropics Group (440e), 70599 Stuttgart, Germany,

Field experience in implementing a small-scale PV milk cooling system in Tunisia and Kenya

Dairy value chains supported by Solar!

Victor Torres-Toledo1, Ana Salvatierra Rojas1 ,

Farah Mrabet1, Joachim Müller1, Tobias Zwirner2

1. Universität Hohenheim, Institute of Agricultural

Engineering, Tropics/Subtropics Group (440e), 70599

Stuttgart, Germany, [email protected]

2. Phaesun GmbH, Brühlweg 9, 87700 Memmingen,

Germany, [email protected]

In cooperation with:

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 2

Why milk cooling?

Milk Quality

Contamination and

proliferation of

microorganisms can

rapidly lead to spoilage

if milk is not properly

handled and stored.

Average range in rural areas

Maximum acceptable level

30°C 25°C 20°C

15°C

4°C


State of the art in Tunisia


State of the art in Kenya


Business opportunities with milk cooling

■ Milk rejection rates around 20% in Africa

■ Milk is picked up only once a day in

isolated farms

■ High quality dairy products rely on high

quality raw milk


Our Strategy: Milk cooling in insulated milk-cans with solar ice

• Cooling on-farm or during transport

• Easy to use

• Adaptable for different sizes

• Flexible operation for morning and evening milk


Milk quality preservation

Cooling curves


Smart solar freezer through an adaptive control unit

Batteries

Adaptive

Control unit


50 kg ice for long-term autonomy + batteries for daily energy balance

Adaptive control unit

Charge Controller Data logging

Batteries 60Ah@24 V


Efficient

Mode -10°C

Sleep mode

0°C

Max. power

mode – 20°C

Stop

Energy saved

in the batteries

Refrigeration adapted to solar energy availability


Daily ice production in dependence on weather conditions

Autonomy of 4 days under unfavorable weather conditions

12 kg/day with 90% reliability in Tunisia

16 kg/day with 100% reliability in Kenya


Autonomy in dependence on weather conditions

Infinite autonomy <4 days >4 days


Projects in the field

Tunisia

Field solar powered milk cooling solution for the

higher efficiency of the dairy subsector in Tunisia

July 2015 – December 2017

10 Systems in 7 farms

• Milk quality preservation for morning milk

• Milk storage over night

• System acceptance and reliability

For more information please visit: https://mel.cgiar.org/projects/spmc

https://mel.cgiar.org/projects/spmc





Sidi Bouzid, Tunisia

5 of 16 farms 22km – 1 hour

2 of 18 Farms 40km - 2 hours

Tunisia

Sidi Bouzid

7 Farms


Traditional

1st Prototype

Commercial Unit


05:00 06:00 07:00 08:00 10

15

20

25

30

35

T e m

p e r a

t u r e

( ° C

)

(b)

On Farm

collecting center

Ambient

Uncooled milk

Cooled milk at 15°C

Cooled milk had 4 times less bacteria content than uncooled milk

Milk preservation during 14 hours overnight ( spoiled without cooling)

0 2 4 6 8 10 12 14

Time (hours)

10

20

30

T e m

p e r a

t u r e

( ° C

)

On-farm milk storage at 8°C

Cooled milk


Projects in the field

Kenya

Program of Accompanying Research for Agricultural Innovation (PARI)

March 2016 – December 2017

3 Systems at cooperative & Farms

• Milk quality preservation during transport

• Milk storage over night

• Business models

For more information please visit: http://research4agrinnovation.org/

http://research4agrinnovation.org/


First system installed in a co-operative in Siaya


First system installed in a co-operative in Siaya


Cooling during transport from satellite collecting points to the co-operative


I n s u l a t e d m a z z i c a n

D i a m e t e r 2 7 c m

M a x m i l k c a p a c i t y 7 . 5 L

M a x . i c e c a p a c i t y 2 k g i c e

H e i g h t 4 0 . 0 c m

To t a l e m p t y w e i g h t 2 . 9 k g

Adaptation for on-farm milk cooling

Locally produced! http://www.mazzican.com/


Additional system shared by several farmers Capacity: 60 Liter / day

Up to 8 mazzi-cans


Ice-blocks of different sizes depending on used milk-cans


Assessment started in May 2017


System cost if exported from Germany

Component Configuration for 60 L/day

Direct current Freezer 615€ (Steca PF166)

PV Modules 600€ (600 Wp)

Battery 250€ (2 x 65 Ah)

Control Panel 160€

25 Tins for Ice blocks 75€

Insulated milk cans 8 x 40€ (7.5 L mazzi-can) 2 x 300€ (30L can)

Installation material 200€

Total cost Approx. 2500-2800 € * *Without considering tax, transport and installation (Export through Phaesun GmbH, Germany)


Conclusions

■ The access to milk cooling can generate business opportunities in rural areas

■ The solar system is not any more the cost driving factor

■ Cooling technology is to be optimized for local conditions and needs

■ The demand needs to be unblocked in cooperation with public and private institutions

for a sustainable introduction of solar milk cooling


Thank you for your attention

Thank you for your cool attention!

Hohenheim, Germany

Siaya, Kenya

In cooperation with:

Documents

1. Universität Hohenheim, Institute of Agricultural ... · Universität Hohenheim, Institute of Agricultural Engineering, Tropics/Subtropics Group (440e), 70599 Stuttgart, Germany,