Efficient energy use was the focus of attention at the "Production-based energy management“ expert conference which took place in Herzogenaurach at the beginning of July 2009. The seminar organized by ProLeiT AG provided an overview of the use of energy at breweries, beverage producers and dairies. Furthermore, the participants were familiarized with options for the implementation of an energy management system in accordance with DIN 16001 in existing plants.

More than 50 participants are sitting close together in the newly inaugurated auditorium and are attentively listening to the presentation by Dr.-Ing. Winfried Ruß. The associate professor from the faculty of Raw Materials and Energy Technology at the Technical University of Munich is reporting on "Optimized energy consumption in the field of production" and fascinates his audience with "16001": This number represents the preliminary European standard which governs the introduction of energy management to companies. The German Federal Government has introduced "DIN EN 16001:2008 –Energy Management“ in order to support companies in the implementation of systems and processes for the improvement of their energy efficiency and contribute to the reduction of energy costs and greenhouse gas emissions. "What is so special about this standard is that companies have to continuously and sustainably improve their use of energy independent of which type of energy", stresses Winfried Ruß. This approach has to be confirmed by an internal audit to be organized once a year. Efficient energy use is thus becoming a company target which will be an essential criterion for the assignment of subsidies by the Federal German Government and the Federal German States ("Länder").

In his opening address, Dr.-Ing. Winfried Ruß impressively demonstrated that even the utilization of renewable resources for energy production is reaching its limits. "Those who have not concluded long-term contracts for the supply of renewable resources have no other option than to invest in more energy-efficient production environments because cultivable land is limited", he emphasized in his address. The DIN EN 16001 standard supports companies in just this approach: It provides transparency with regard to the energy consumption of individual plants, analyzes the production process for various products and identifies potential for improvement.

"The improved efficiency ratio of steam generators, the substitution of fuels by renewable energy sources and also optimized compressed air generation and refrigeration all provide significant potential for efficient energy use", explained Winfried Ruß. Compressed air in particular is the most expensive type of energy because only 5 % of the energy used will ultimately be converted into power. The avoidance of waste is therefore of primary importance, especially in this field. But the use of waste heat has proven particularly efficient as well. Dr. Ruß quoted two examples in order to demonstrate that the waste hot water from an average dairy provides the same energy as more than 700,000 liters of fuel oil/year. And for a brewery with a production capacity of 500,000 hectoliters per annum, the waste hot water also corresponds to 270,000 liters. This potential must be identified and utilized. Those who have implemented an energy management system already today are particularly well equipped to evaluate relevant measures, Dr.-Ing. Ruß continued.

Using a brewhouse as an example, Dr.-Ing. Ruß demonstrated the approach to be pursued in drawing up an energy balance sheet. "At first sight, the wort copper always seems to be the number one energy user. But if you take a close look at the energy loss in percent, the lauter tan and wort cooling equipment is losing far more energy although - as shown in the example of the lauter tun - no energy is supplied from outside." This energy is included in the product itself and can be recovered by means of heat pumps or paraffin heat storage facilities. In addition, short boiler starts performed to maintain the necessary operating pressure have a negative impact on the energy balance sheet. This phenomenon is due to recipes with different energy requirements. The staggering of start-up times in production preparation provides significant savings potential.

Consistent monitoring of all state data

"Modern energy management is complex and not just restricted to one specific energy source, field of application or a specific part of the value added chain", summarized Winfried Ruß and thus provided the ideal introduction to the next point on the agenda: In his presentation, Stefan Stenzel of ProLeiT reported on online and offline energy data acquisition and evaluation in breweries. According to Stefan Stenzel, precise and complete data acquisition is in principle a major prerequisite for the assessment of energy consumption values. But the problem in existing plants is the diversity of sub-plants based on different automation systems, different counting devices and proprietary interfaces. Since, in most cases, the expected ROI cannot compensate the retrofit costs, the data model of the energy management system must allow mixed acquisition. For example, the direct read-out of electricity meters and the saving of load profiles are essential in this context. Plant iT provides the standard modules required for these purposes. After all, delivery meters for the consumption of process water, carbon dioxide or hot water for cleaning processes deliver their measured values to the process controllers anyway.

In addition, the counters installed at the different process stages of production, filling and packaging must e.g. be read out offline using a PDA system and entered later. Based on this data, Plant Acquis iT creates standardized data records which are saved in an SQL server-based realtime database. At the push of a button, the data can be exported into an Excel-readable format. Production managers therefore have the option of initiating shift-, order or batch-related requests and issuing daily, weekly, monthly or annual reports. Based on the corresponding characteristic numbers, even particularly detailed issues can be traced back within the individual plant sections or machines. The Plant Acquis iT web interface allows the user to write platform-independent reports on the different energy balances.

Energy data acquisition as a decision-making aid for investment

But the expert conference was not only a forum for the exchange of theoretical knowledge: In a fascinating presentation, Frank Jäger reported on energy management in soft drink production. Franken Brunnen in the Bavarian town of Neustadt/Aisch wanted to replace its obsolete heat supply system with a state-of-the-art solution, because the steam boiler installed in 1978, with an output of six tons, no longer complied with modern requirements. "But we could only roughly estimate the dimensions of the new boiler", Frank Jäger commented. "Only for monthly consumption values die we have a consistent counter tree structure and transparent energy data. But unfortunately, the consumption values could not be assigned to the individual plants."

Franken Brunnen installed the ProLeit energy management system in order to have a reliable decision-making aid for its requirements. At the same time, heat meters were installed in the brewhouse in order to determine the energy consumption in terms of hot water. The company wanted to implement steam meters for recording steam quantities, and gas meters for measuring the consumption of the individual gas boilers. At the same time, electricity meters were installed in the outgoing feeders of the transformer stations and individual plants. The counters were connected by means of an existing bus system and integrated in the energy management system. After six months, sufficient data was available in order to make the relevant decisions for the investment planned. The data evaluation showed that a steam boiler with an output of four tons was sufficient. The hot water boiler used so far, with a heat capacity of 2,400 kW, will also be used in peak consumption times in winter, and the old boiler will be installed as a redundant component.

"Thanks to the new energy management system, we can also precisely determine the energy consumption of individual products in production plants and specifically optimize production processes", explains Frank Jäger. For example, different plants start up at different times in order to avoid peak loads. A peak load shedding feature monitors the ventilation systems of production plants, the air conditioning systems at the office and in control rooms, and also the waste water neutralization systems. Based on this sophisticated approach, the company is trying to reduce current peaks and the level of gas supply reserve required at its Neustadt/Aisch production facility. The reduction of current peaks from 1,850 kW to 1,700 kW will allow Franken Brunnen to save about € 10,000 per annum. Furthermore, the reduction of the gas supply reserve from 4,000 kWh to 3,000 kWh will reduce the company's energy costs by an additional € 7,000.

Installation of an energy management system in breweries

"Customers always say that the introduction of an energy management system is too complex, that there was not sufficient time or that they lack appropriate methods and expertise", Michael Sembenotti of ProLeit declared at the beginning of the next presentation. "But with some support and a structured systematic approach, challenges of this kind can be easily overcome." Using the example of a brewery of the Radeberger group, he illustrated the progressive introduction of an energy management system. First of all, all primary energy data must be collected and managed, and the costs controlled. To do this, all M bus-capable electricity meters are interlinked based on the IEC 1107 protocol. Water and heat flow meters are integrated in the process control and send standardized volume or mass flow values directly to the plant server. On the secondary energy level, the consumption of heating and sterile steam, hot water, coolants and gases is acquired in the same manner.

"Instead of integrating data on a large scale right from the start, a progressive approach should be pursued," explained Michael Sembenotti. "It does not make sense to interconnect the entire data acquisition system in a first stage. For an initial assessment, it is sufficient to acquire the incoming supply and the main departments and buildings." Further relevant consumers can be progressively integrated in the process control system later. This approach results in the implementation of an intelligent load management system for the optimization of the energy balance sheet. For example, the electricity balance sheet of a brewery of the Radeberger group indicates the power consumption of the individual departments in percent in order to allow comparisons. This system promotes competition among individual departments and encourages employees to accept innovations.  "This is also part of operative energy management in accordance with the DIN 16001 standard which prescribes the ongoing monitoring of consumption values, the evaluation of suitable characteristic numbers and the implementation of a benchmarking system", comments Michael Sembenotti. "When analyzing data, we always look for load peaks, limit value violations and periodic increases in consumption. Relevant values show optimization potential because most periodic increases in consumption values can be prevented through improved planning." For example, it is not necessary that all major consumers be switched on simultaneously on a Monday morning. Beginning shifts at different times can significantly even out the energy consumption at the start of work. Parameterizable switch-off conditions ensure compliance with the overall power consumption permissible and minimum operating times as well as minimum idle times of systems. For example, wort cooling and tank cleaning can be assigned priority over "less important" consumers such as air conditioning systems or fermentation tank cooling zones. "Only complete integration can avoid technical faults and thus allow coordinated load shedding and the operation of utilities at optimal operating parameters", Michael Sembenotti continues.

Installation of an energy management system in dairies

The presentation by Roland Riedl sparked the interest of dairy experts. Depending on the product range, energy costs account for approximately 1.5 to 5% of a dairy's annual turnover – for large groups, these costs can reach amounts in the range of tens of millions of euros. Savings in the fields of electricity, cooling, compressed air and lighting have an immediate positive impact on the financial figures. "In most cases, the savings potential cannot be determined at first glance", explains Roland Riedl. Some actuators are difficult to influence, and certain measuring equipment urgently needs replacement, or individually wired communication paths are inefficient. In these cases, the entire company must be carefully scrutinized and obsolete equipment modernized accordingly. Progressive migration provides the operator with the option of recovering the heat produced by plate or tube heat exchangers and separators and spray towers, of controlling the speed of compressor drives during operation, and further promoting automation.  "Thanks to an energy management system, losses can be controlled more effectively and a comprehensive automation solution for all plant sections from milk receivals up to filling can be established", explains Roland Riedl. The PLCs capture data for storage in an SQL database, and clearly arranged Excel sheets provide the operator with a precise overview of consumption values and losses. The uniform data structure facilitates certifications and inspection. With Plant iT, changes in process sequences can be configured based on a structured approach and implemented with minimum production downtimes. "If data is visualized accordingly, it is easy for a company to convince its employees to utilize potential and to design processes as efficiently as possible", Roland Riedl summarized.

In brief

No other event in recent times has provided so much valuable information!  And for all those who could not take part: Another specialist conference of this kind is scheduled to take place in March 2010. Perhaps some participants at this year's seminar will benefit from this opportunity in order and report on the introduction of an energy management system in their company next year.