As flour millers face growing pressure to improve both competitiveness and environmental performance, the biggest sustainability gains will come not from a single breakthrough machine, but from better grain sourcing, tighter yield control, and data-driven energy management, says Silvan Trunz, Head of Sustainability at Bühler Milling Solutions. Speaking to Namik Kemal Parlak, Editor-in-Chief Miller Magazine, Trunz says the next generation of milling plants will be defined by deeper digital transparency, more adaptive automation, and a broader effort to improve resource efficiency across the entire value chain. To explore how these goals can be translated into practical results on the mill floor, we asked Trunz to share his insights.

When we talk about sustainability in flour milling, what should millers focus on first to make a meaningful impact?

The biggest impact usually comes from three areas: raw material footprint, yield losses, and energy consumption inside the mill. If possible, millers should start with grain sourcing — local, lower-footprint raw materials can make a major difference. But where sourcing options are limited, the next best focus is overall yield optimization. Every kilogram lost carries the footprint of cultivation, transport, and processing. That makes cleaning efficiency, process stability, and adapting settings to harvest conditions especially important. The third key lever is energy. Here, the first step is transparency: measure energy not only for the whole plant, but also by process steps and major consumers. Define clear baselines such as kWh per ton and extraction rate. Once that visibility is in place, priorities become much clearer.

Where are the biggest "hidden" inefficiencies in a typical flour mill today that often go unnoticed?

In most mills, inefficiencies are not dramatic breakdowns. They are small, continuous losses that add up over time. Typical examples include pneumatic systems with too much airflow, fans and aspiration systems that are not adjusted dynamically, worn rolls or suboptimal roller gaps, compressed air losses, and yield losses caused by process instability. Another common issue is the lack of real-time visibility across the plant. Many mills are mechanically sound but not yet optimized from an energy and performance point of view. That is why process transparency and digital monitoring are becoming so important.

Bühler aims to reduce energy, waste, and water by 50% in customers' value chains. In the specific context of milling, which technologies are currently contributing most to this ambitious goal?

Here I’d like to set the view bigger first. It is important to look at the full value chain. Milling is only one part of the footprint, so real progress comes when upstream and downstream partners work together. For example, does it make sense to ship 3-4% screenings around the world? Or should we remove these before shipping? What needs to be done and change, that such logical steps can happen without any revenue losses in the value chain? The answers to such questions, which need to be solved from the value chain as such and not from a single chain link, need to be tackled. Within the mill itself, the strongest levers today are technologies that improve yield, process stability, and energy efficiency. These include well-designed cleaning systems, efficient integrated grinding systems, optimized pneumatic conveying with variable-speed control, automated process control, and digital tools for monitoring and benchmarking. In practice, sustainability in milling is rarely about one breakthrough machine. It is about combining improvements across the entire process so that the system performs better as a whole.

THE REAL BREAKTHROUGH LIES BEYOND HARDWARE

Reducing kWh per ton is the ultimate goal. Beyond hardware, which recent technological breakthroughs have shown the most significant impact on specific energy consumption (SEC)?

Beyond hardware, the biggest progress is coming from data-driven process optimization. Today, mills can measure energy use more granularly, compare sections and shifts, detect deviations earlier, and adjust parameters dynamically instead of relying only on fixed settings. This is where software, analytics, and automation create real value. Even a very good mill will not reach its full potential if settings are not continuously optimized. The biggest breakthrough is therefore not only better machinery, but the combination of process design, connected equipment, real process data, and intelligent control.

WHERE EXISTING MILLS SHOULD BEGIN

For existing mills not originally designed for sustainability, what are the most realistic and cost-effective first steps toward becoming "greener"?

For existing mills, I would recommend starting with measures, practical, and fast to implement. The most realistic first steps are:

1. Establish an energy and yield baseline

2. Measure energy more granular maybe also larger energy consumers separatly

3. Optimize pneumatic systems and fan control

4. Train operators using data, not assumptions

5. Introduce digital monitoring for ongoing improvements

6. Build an improvement and innovation culture

In many cases, there is already significant potential in the installed base. You do not always need a complete rebuild to make meaningful progress.

How do platforms like Bühler Insights or Mercury MES help millers turn invisible data into measurable gains in resource use?

These platforms help mills move from being reactive to data-driven. They make it possible to monitor energy consumption by line, section, batch, or asset; track KPIs in real time; link process behavior to yield, quality, and uptime; benchmark shifts or seasons; and detect deviations early. This matters because many inefficiencies are not visible in day-to-day operation. A plant may appear to run well while energy use is quietly increasing. Digital tools make those patterns visible — and once they are visible, they can be improved.

Can we expect a future where a mill automatically optimizes its energy consumption based on grain variety and ambient conditions without human intervention?

Yes, that is clearly the direction the industry is moving in. The building blocks already exist: sensors, real-time monitoring, advanced control systems, historical process data, and AI-supported optimization. Future mills will increasingly adapt settings based on raw material properties, moisture, temperature, throughput, flour quality, and process targets. Human expertise will remain essential, but the system will increasingly support millers and operators with recommendations and, in some cases, automatic adjustments. The self-optimizing mill is no longer a distant vision — it is a step-by-step reality.

Sustainability also means utilizing side streams. How is Bühler helping millers transform bran and other by-products into high-value energy or nutritional sources?

Side streams are often undervalued, but they offer real potential. Bühler helps customers create more value from bran and other fractions through the production of brown and wholegrain flours, fiber-rich ingredients, and other food or nutritional applications. The goal is to shift side streams from being seen only as by-products to being recognized as valuable raw materials. In some cases, side streams can also support energy recovery. But from both a sustainability and business perspective, the highest value often lies in food and ingredient applications. Bühler’s test and application centers support customers in exploring these opportunities and developing new product concepts.

How close are we to a carbon-neutral flour mill, and what are the main technical or economic hurdles remaining?

A low-carbon mill is absolutely achievable. A fully carbon-neutral flour product is more complex, because much of the footprint sits outside the mill itself — especially in grain cultivation. The main hurdles are the footprint of agriculture, the availability and cost of renewable energy, legacy infrastructure, investment constraints, and limited visibility on Scope 3 emissions.

If we talk about mill operations alone, carbon-neutral milling is technically possible in many cases. The return of investment is different in every region and mainly depending on green energy sourcing. But if we talk about the full flour footprint, then collaboration across the value chain is essential — especially with grain suppliers and downstream customers.

START SMALL, BUILD MOMENTUM

Many millers worry about high capital costs. What is your advice to those who want to start their green journey but are concerned about the initial investment and ROI?

My advice for existing mill is simple: start small, but start now. Do not try to do everything at once. Begin with measures that save money while reducing footprint: optimize processes, improve yields, stabilize operations through monitoring and automation, reduce waste, and increase transparency for customers and compliance. Not every improvement requires high CAPEX. Many mills can begin with optimization, monitoring, and selective upgrades, often with relatively short payback times. The key is to build momentum with practical wins and then reinvest those savings into bigger improvements. My advice for new plants is to evaluate different CAPEX versus OPEX scenarios carefully. Over several years of operation, a higher upfront investment often pays off through substantially lower operating costs, particularly in energy consumption.

FIVE PILLARS OF THE NEXT-GENERATION MILL

What will define the next generation of sustainable milling plants over the coming decade?

The next generation of milling plants will be defined by five things:

1. Higher energy efficiency by design

2. Much deeper digital transparency

3. More adaptive and automated process control

4. Better raw material utilization and side-stream valorization

5. Closer integration across the value chain

In short, the sustainable mill of the future will not simply use less energy. It will be more connected, more intelligent, more flexible, and more resource-efficient across the full system. That is where the industry is heading, and I am sure the mills that embrace this early will gain both competitive and environmental advantage. For me, sustainability in milling is not a separate agenda. It is about running a mill better — with less energy, less waste, more transparency, and stronger long-term competitiveness.

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