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Using the sun to cool the milk

Approximately 95% of the milk produced in Nigeria comes from nomadic herdsmen that use mainly the White Fulani Cattle.

Alignment with SDGs


Snorri Sigurdsson, Senior Project Manager Raw milk supply and production Arla-Nigeria • Nigeria


In many countries around the world milk spoils because it is not cooled quickly enough after milking. To preserve the quality of its raw ingredient as best as possible, dairy cooperative Arla Foods, recommends that cooling takes place within the first two hours. However, lack of infrastructure, lack of access to cold water, poor access to electricity, for example, limits many farmers’ ability to cool the milk down shortly after milking. It has been estimated that around the world tens – if not hundreds – of million litres of milk gets spoiled ever year due to these limitations. One way in which milk spoilage can be greatly reduced is through the use of cooling units, that can be transported and used off the grid – powered by the sun through the use of solar panels.

In Nigeria, Arla Foods is trailing different systems to cool the milk down using the sun to solve this problem. As well as increasing farmers’ income as more milk will be of sellable quality, milk spoilage and food waste is reduced as a bigger share of milk can be consumed.

Dairy production in Nigeria

Approximately 95% of the milk produced in Nigeria comes from nomadic herdsmen who move around with their cattle depending on the weather conditions and accessible vegetation. These herdsmen use mainly the White Fulani cattle breed, which is the main breed not only in Nigeria but also in Chad, Ghana, Niger and Togo. This cattle breed is extremely resilient and well adapted to the harsh environment in the Sahel belt south of the Sahara Desert, where drought and heat can be a major issue for farmers. The downside of this cattle, however, is the breed’s extremely low yield. Cows often only give 1.5-2.5 litres of milk per day and each herdsman is often only selling 5-10 litres of milk daily.

In June 2020, Dairy Council of California launched Let’s Eat Healthy, an initiative that brings together educators, health professionals, change-makers, and community leaders to elevate the health of children and families. Let’s Eat Healthy invites multidisciplinary coordination, collaboration, and co-creation to champion community health by teaching and inspiring healthy eating habits and making healthy, wholesome foods accessible and affordable to all California’s diverse communities.

Milk collection challenge

Because the nomadic herdsmen move around with the cattle, the delivery of milk to an established Milk Collection Centre (MCC) is sometimes not possible because of long distances and lack of proper infrastructure in the area the milk is produced. This has led to a collection system where small volumes of milk are gathered in several places and milk from different herdsmen is combined with other milk. This milk is then transported, often by motorbikes, to the nearest MCC for quality measurements, weighing and cooling. This system of milk collection has one major issue, which is the lack of quick cooling of the raw milk. Because of the small deliveries from each herdsman and long distances from the herds to the nearest MCC the milk is often not cooled down for many hours after milking. This has led to high percentages of spoiled milk, that is, milk that cannot be used for dairy processing as it becomes contaminated with bacteria.

Farming off the grid

For most established farmers around the world this issue with milk quality is not a major factor to consider because of higher milk volumes per farm, and for most of them, good access to grid electricity. For the herdsmen in Nigeria this is however a major factor and even if the farmers would like to cool the milk down, that is not possible in most places as there is no access to grid electricity. To compensate for that Arla-Nigeria has now looked into solutions that are based on solar power as Nigeria, placed only 1.500 km north from equator, has many sunlight hours every day, all year round. At the same time the solutions that are sought after need to be portable – with the farmers are moving regularly the system needs to be able to follow the farmers!

Solar power helps the the nomadic herdsmen on the delivery of cooled milk to an established Milk Collection Centre

3 trial solutions

There are many ways to cool down the milk with energy from the sun and some examples are shown in photos 1, 2 and 3. These solutions can both be found as complete produced units, or used as a combined technology where known cooling solutions are powered with energy made by solar panels. No matter what methods are used, the main issue to solve is to find a way to cool down the milk as quickly as possible after milking, to stabilize the raw milk and slow down the growth rate of bacteria in the milk before pasteurization.

Promising outcome

To date, one of the 3 methods referenced, has been tested by Arla-Nigeria and first results show that the raw milk quality has improved as expected. The method in question uses a normal freezer that is powered by the sun. During the night, when no electricity is generated, the ice in the freezer keeps the unit cold and ready to receive the milk next day. When the milk is delivered and cooled down it is taken to the dairy plant after which, in the middle of the day, a new layer of frozen water builds on the inside of the freeze, ready to cool the next batch of milk. The other 2 methods, which are specially designed and produced methods to cool milk down, will be tested in late 2022 and early 2023 are the ones showed on photo 2 and 3.

Photo 1. Example of a simple solution for milk can cooling. Solar panelled powered freezer, to rapidly cool down milk.
Photo 2. Specialized milk can cooling unit powered by the sun.
Photo 3. Solar powered cooling unit, specially designed for milk jars. © Galactea.


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