Pretty hot coffee

While a factory was already on its way to Asia by ship, a team from umlaut optimised the energy efficiency of the plant. The result: coffee roasted in a way that is more climate-friendly than ever before.

Climate protection is becoming an economic factor. A customer of the German machine and plant manufacturer Probat, who was planning a coffee roasting plant for the Asian market, realised this too. Suddenly, they not only wanted it to be reliable and secure but also especially environmentally friendly. The bonus challenge: at this point in time, the plant – which was the size of three detached houses – was already on its way down the River Rhine on a freighter.

The passage to Asia takes between two and three months. While the freighter was travelling through the Strait of Gibraltar, the telephone rang at umlaut: Do you do energy efficiency as well? umlaut does.

Energy efficiency on töp

The principle is quite straightforward and starts with the following questions: Where is energy consumed? Where is energy produced? Where can we combine these processes so that as little electricity, heat or gas as possible needs to be fed in from outside?

Before getting started, it's important first of all to listen. After all, the Probat engineers are the experts when it comes to roasting coffee. You can only find potential areas for optimisation if you have a full understanding of a plant, down to the last detail. There are no short-cuts and no standard solutions – instead, by the end of the analysis, we have an individual energy overview that closely examines every step in the process.

By the time the freighter was approaching the Suez Canal, the Probat and umlaut engineers were already busy developing their ideas. Starting with the simple things: improving the insulation of the piping, installing more efficient ventilators and pumps, and using CO₂-neutral biogas instead of environmentally-damaging natural gas.

Then things start to get more complex. For example, with the skin of the coffee bean. Would it be possible to use the material that falls off the beans (chaff) in one of the roasting steps – the so-called "first crack" – as a fuel? We are talking about six tonnes of raw coffee per hour. In this case the intervention didn't in fact turn out to be worth pursuing. However, the engineers discovered a suction device that fishes out the chaff – running at full power the whole time. More efficient system control here can save 1 kg of CO₂ per tonne of raw coffee.

It's always worth having a good look at the chimney: the roasting process generates a lot of waste heat for a short period of time – and some of this heat is lost from the system. Using this exhaust air to warm up the raw coffee before roasting can lead to savings of 28 kg of CO₂ per tonne of raw coffee. Pretty good for the climate – and afterwards, the air is still warm enough to pre-heat the burner air (further potential savings of 4 kg of CO₂ per tonne of raw coffee).

It is not possible to implement everything, for example with regard to product quality. Using condensation water for "quenching" – the pre-cooling of the roasted coffee? Not feasible for quality assurance, because aromas might be introduced into the coffee batch. Other suggestions are examined with regard to investment costs or technical feasibility – and rejected if they aren’t effective.

The overall results are still impressive: potential savings of 42 kg of CO₂ per tonne of raw coffee were identified before the freighter had even sailed around the coast of India. This is the equivalent of 1,655 tonnes of CO₂ per year. By the time the ship had berthed in Asia, the plans for the new plant had transformed it into the most efficient roasting plant in the world.