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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, info440e@uni-hohenheim.de

2. Phaesun GmbH, Brühlweg 9, 87700 Memmingen,

Germany, info@phaesun.com

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 3

State of the art in Tunisia

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 4

State of the art in Kenya

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 5

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 6

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 7

Milk quality preservation

Cooling curves

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 8

Smart solar freezer through an adaptive control unit

Batteries

Adaptive

Control unit

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 9

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

Adaptive control unit

Charge Controller Data logging

Batteries 60Ah@24 V

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 10

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 11

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 12

Autonomy in dependence on weather conditions

Infinite autonomy <4 days >4 days

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 13

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 14

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 15

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 16

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 17

Sidi Bouzid, Tunisia

5 of 16 farms 22km – 1 hour

2 of 18 Farms 40km - 2 hours

Tunisia

Sidi Bouzid

7 Farms

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 18

Traditional

1st Prototype

Commercial Unit

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 19

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 20

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/

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 21

First system installed in a co-operative in Siaya

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 22

First system installed in a co-operative in Siaya

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 23

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 24

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/

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 25

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

Up to 8 mazzi-cans

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 26

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 27

Assessment started in May 2017

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 28

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)

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 29

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

© University of Hohenheim│ Institute of Agricultural Engineering │Tropics and Subtropics Group 30

Thank you for your attention

Thank you for your cool attention!

Hohenheim, Germany

Siaya, Kenya

In cooperation with: