Water plays an essential role in Emmi's production processes. Emmi's Swiss facilities use just under three million cubic metres of water each year. Reusing water is therefore an important environmental target. Water is used for cleaning, cooling and heating, which is where energy comes into play.
When two substances at different temperatures meet, their temperatures equalise. Put more simply: combining hot and cold results in tepidity. The process is called heat transfer. For this to happen, the two sources do not even need to be in physical contact - just being close to one another is sufficient. If you understand this basic principal of physics, you can employ it to save energy. Emmi's Swiss facilities have implemented numerous heat-recovery projects in recent years, with water playing an important role as an energy source.
Pioneering projects in Ostermundigen
The origins of heat recovery from water at Emmi lie in Ostermundigen, where heat has been recovered from waste water since 2008. Around 17,000 m3 of waste water per day are generated from cleaning and sterilisation processes. The extracted heat is used to prewarm cleaning water, which saves over 260,000 m3 of natural gas per year, reducing Emmi's CO2 emissions by 520 tonnes.
The inter-company Wärmeverbund Mösli district heating network, which has been in existence since 2009, is also pioneering. Using a heat exchanger, energy from warm water from the cooling processes at Emmi's Ostermundigen facility is transferred to cold water from the Mösli energy plant. This then flows back to the Mösli energy plant as tepid water.
The plant supplies properties in the Mösli area via district heating pipes. The heat fed in by Emmi supplies one-third of the district heating network's needs and reduces CO2 emissions by just under 90 tonnes per year. The electrical equipment rooms in Ostermundigen have also been cooled with recirculated cooling water for around a year now. And right on time for winter 2013-14, Emmi was able to start heating the tanker depot with tepid recirculated cooling water, which also takes the pressure off the cooling towers.
In Emmi's most westerly production facility in Switzerland, the water cycle also begins with a cooling process. In contrast to the majority of other facilities, the Mouton site is able to draw on water from its own spring. The water has a temperature of 10ºC and is ideal for cooling the compressors. The water absorbs heat energy from the compressors and can reach a temperature of up to 45ºC. This heat is used for a multitude of purposes, such as heating the Gruyère rock cellar in the winter.
Exemplary water usage in Suhr
The declared objectives of Emmi's environmental policy are to minimise fresh water consumption and use energy efficiently by concentrating on reusing water and using energy economically.
This is demonstrated in exemplary fashion by a current project devoted to water usage and heat recovery in Suhr. Using state-of-the-art technology, the waste heat from existing processes is recovered and provided for use as warm process water at different temperatures. To use water sustainably, heated drinking water that is a by-product of pasteurising milk is collected in tepid water tanks, rather than being discharged as waste water. This clean water can be reused by cooling the milk from 95ºC to 40ºC, while at the same time heating the water to 40ºC. The water can then be used once more as rinsing water before being discharged into the sewerage system. By such means, Mittelland Molkerei in Suhr saves up to 70,000 m3 of fresh water and almost 3 million kWh of energy per year, which is equivalent to the annual energy requirements of around 100 Swiss households. This substantial investment of CHF 1.2 billion also has a beneficial effect on Emmi's CO2 balance, reducing it by 550 tonnes of CO2 emissions per year.
Pinch analysis shows potential
The pinch analysis conducted in Emmen has revealed that there is considerable untapped energy savings potential in water at this production facility. As a result of this discovery, various measures have been planned for 2014 to make use of this heat in future, which means that it should soon be possible to heat the buildings by means of heat from waste water.
But not only water provides additional energy savings potential. This is can be seen from the Landquart and Kaltbach cheese facilities, which have been obtaining energy from whey for some time. This gives rise to annual savings of over 50,000 litres of oil in Kaltbach alone. This is worthwhile - for both Emmi and the environment.