Energy Efficiency in the Baking Plant

The process of baking inevitably consumes a lot of energy, but it also presents a number of opportunities to streamline energy usage, including the use of improved components, adoption of efficient processes, and setting up of state-of-the-art baking facilities.

Steps to Savings

The Carbon Trust is an independent, expert partner of leading companies around the world, helping them contribute to and benefit from a more sustainable future through carbon reduction, resource efficiency strategies and commercializing low carbon technologies. Paul McKinney, senior manager – technology programs, shared with us the organization’s expertise into stepping up energy efficiency. “We would always encourage investing in sub-metering, in order to more accurately determine benchmarks, identify deviations in energy use and monitor the impact of energy saving projects.” In order to estimate costs for improvements and energy savings, the starting point is to ensure that you have good sub-metering, to precisely determine current consumption. This should provide equipment suppliers with valuable data to be able to estimate the potential savings that could be made through equipment upgrade or replacement.

There can be a lack of monitoring to determine where energy consumption is high, which is common with many industrial processes. Gas consumption of the boiler may be measured, but direct steam metering is less common. Monitoring of gas consumption by individual ovens also may not be carried out. Furthermore, electricity may only be monitored for the site or general site areas.

According to the study completed by the Carbon Trust in 2015, savings of 4.7% for bread ovens are possible by linking variable flue gas speed drives with combustion control. These savings can be significant when the costs for operating an industrial bread oven are calculated. A typical oven will cost over GBP300,000 in gas to operate each year, so 4.7% represents GBP14,000 in annual savings.

Large quantities of energy are lost through oven flues and exhausts. He adds, “However, heat recovery in bakeries is not commonplace. Previous attempts have caused problems with contamination of the heat exchanger, and problems with the performance of the heat exchanger (recovering sufficient heat). It can also be difficult to match the production of waste heat with the potential for using it. However, heat recovery is an important energy saving technique and should continue to be re-evaluated.” In the UK, there is a support program for this, run by the government – IHRS.

Another factor to consider when evaluating the oven’s efficiency is the use of tins. Usually made of steel, they are a significant source of energy losses. Tins have to be heated to the oven operating temperature during baking and cooled again before a new dough piece is added. Typically, the ratio of steel to bread passing through a bread baking oven is 2:1. The losses per loaf are the same for a direct and indirect oven, but for direct-fired ovens, the absolute percentage loss is higher because the ovens are more efficient.

Furthermore, combustion conditions are often not monitored other than during burner servicing. “Burners are often set-up to ensure reliable oven operation and good product quality. Significant savings on flue gas heat losses could be made by optimizing the burners for good energy efficiency and reducing the excess air levels.

A certain amount of excess air is required to maintain good combustion while minimizing flue losses. Improving and sustaining improvements to combustion conditions can be delivered by regularly servicing the burners. Of course, safe operation of the oven is paramount and any controls need to be fail-safe so that burner control does not result in dangerous operation.

It has been estimated that gas savings of up to 10% of can be made for an indirect oven by reducing the levels of excess air during combustion.

A checklist for further improvements:

  • Ensure that ovens are regularly inspected. Check for worn or broken oven seals or damaged insulation, both of which lead to wasted heat energy and ensure repairs are carried out promptly. Encourage employees to look for signs of inefficient ovens, such as hot air blowing out of the oven ends. Instances should be reported straight away and maintenance checks made.
  • Maintenance is also important for ancillary services such as compressed air and motors: ensure maintenance is carried out regularly and follow the manufacturer’s documentation for the recommended maintenance schedule. For compressed air, maintenance routines should include lubrication, oil changes, and filter replacement. A well-maintained compressor can be 10% more efficient than one that is poorly maintained.
  • For motors, regular maintenance can reduce energy consumption by as much as 7%. Maintenance programs should consist of lubrication schedules, cleaning, belt tensioning and alignment checks. It is also worth considering using predictive maintenance techniques and software that can indicate in advance when parts will need replacing.

An Industry Analysis

Automation has emerged as an important development in this context. By reducing human contact with the baking process, it aims to reduce the chances of contamination, which, in turn, could enhance the production process. Waste control is another focus area for equipment manufacturers. The failure of equipment to run efficiently could generate wastage in the form of overbaked or underbaked products and thereby affect the overall production capacity of a commercial bakery. The adoption of enhanced technologies such as artificial intelligence and Internet of Things (IoT) has further enhanced production processes; the use of these technologies aims to reduce human intervention in the production processes in bakeries, and thereby reduce operational costs and increase productivity. Robotics has emerged as a plausible solution to some of the challenges being faced by bakeries today, especially in commercial bakeries that require remote monitoring of operations.

Also, some bakeries are adopting measures and modifying their equipment to comply with their energy-saving goals. For instance, pre-heating the air used in gas burners from approximately 77°F to 284°F helps in the recovery of more than half of the energy lost in the exhaust flue to ensure reduced gas consumption and a smaller carbon footprint. Also, some new bakeries are installing heat recovery modules with complete insulation by using stainless steel outer panels. Such insulation systems can also be retrofitted in old bakeries. This measure can save 112kW-115kW of energy and can result in major cost savings for the concerned bakeries.

Technology is Key

For energy efficiency, bakeries need to focus on acquiring real-time insights into the working of baking equipment. This factor is encouraging bakeries to invest in advanced technology. Ritesh Kumar, senior industry analyst, Technavio, shared with us the example of Bretzel Bakery, a Dublin-based artisan bakery that has invested in IoT to help it reduce energy consumption: “IoT helps to capture real-time data through sensors and uses cloud-based analytics to gain critical insights. A vast magnitude of data are captured every week to help the company identify areas of improvement that include the most economical way to use gas or electric ovens. Through these insights, the company is able to keep track of costs related to daily energy consumption.”

Environmental concerns and strict government regulations are prompting manufacturers in the baking industry, among other manufacturers in the food and beverages industry, to focus on sustainable energy practices. For instance, waste heat can be reused through various heat recovery systems, that convert exhaust heat to hot water, for other activities such as cleaning, according to Technavio’s analyst.

In addition, equipment maintenance is essential to energy efficiency. Periodic maintenance includes regular cleaning to prevent contamination of the products being processed and prevent bacterial growth. “Bakeries are also advised to conduct preventive maintenance activities to identify worn out parts to prevent a complete breakdown. Training the staff to use equipment in accordance with the manufacturer’s guidelines is also a part of preventive maintenance,” added Kumar.

Trends in Energy-efficient Technology

In large bakeries, the oven is the major consumer of energy, followed by the prover, cooler and steam boiler. Together, they account for more than half of energy consumption and carbon emissions in a bakery, Technavio highlighted. “Ethanol, a volatile organic compound (VOC), is the primary emission from bakeries and is produced when dough is exposed to high temperatures in an oven. It is converted to smog when it comes in contact with other VOCs.”

With energy efficiency as the need of the hour, manufacturers are adopting practices that could take them closer to their goals of environmental sustainability. Some of these practices include improving the insulation of production plants, bringing down the amount of ambient air entering dispatch areas, ensuring variable speed drives on bakery ventilation systems, and reducing the leakage of compressed air. They are also adopting measures such as the periodic shutdown of major plants that include ovens, coolers, and conveyors periodically, the specialist observed.

The best practices also involve the adoption of technology that can ensure energy efficiency. “For instance, one of the most important components in the manufacture of bread is moisture,” he added. “A conventional bread fermentation chamber works with steam, where the conversion of water into steam consumes a significant amount of energy and also affects the quality of the bread produced.

  • Bakeries across the globe are increasingly adopting ultrasound humidification technology to bake bread; it helps to reduce energy consumption and also maintains the quality of the bread. During this baking process, the humidity of the bread fermentation chamber is modified to match the humidity of the dough being baked—doing so prevents the dough from losing moisture. In this way, the use of ultrasound humidification technology helps to overcome the shortcomings of conventional technologies, primarily energy loss, and also helps in maintaining the consistency of the product created.”
  • Infrared ovens are being adopted by commercial bakeries worldwide. These ovens use ceramic plates heated by flames or electric coil to heat or generate infrared energy and transmit it to the surface of the product being baked, but without heating the ambient air. These ovens are 50%-80% more efficient than conventional ovens, he explained, as the baking process does not heat up large volumes of air. Also, they help to cut down on baking time by nearly half. “For instance, an infrared oven can bake bread in nearly six minutes compared with the 17 minutes in a conventional baking oven. Also, the power level initially at 100% can be reduced to 30%-50% during the second and third stage of baking. Thus, the use of infrared ovens reduces both overall energy consumption and baking time to provide more efficiency to a baking plant.”
  • Reflective coatings that contain high-emissivity ceramic materials are also finding increased used among bakeries. These coatings are being used on pans or on the interior walls of ovens and burners; they can absorb heat and reflect it back in the form of infrared energy waves. By doing so, these coatings can reduce emissions and fuel consumption and thereby cost of operations. In the long run, reflective coatings also contribute to the long lifespan of ovens as less surface area is exposed to direct heat.
  • Multilevel ovens are also helping commercial bakeries become more energy efficient. These ovens can increase the throughput of bakeries; the different levels of the ovens can be set to different temperatures, humidity levels, and air flows. Hence, these ovens provide more flexibility to the production processes and also help to save energy loss by enabling more control over energy use. Ovens have a lifespan of around a decade and the flexibility offered by multilevel ovens could enable bakeries to expand their product portfolios without the need to invest in additional equipment.

In the long run, optimization of baking processes will remain the top agenda of bakeries focused on energy efficiency. The industry is likely to focus on new facilities, he anticipates, to bring about automation, streamline existing processes, deploy robotics, and focus on reducing equipment downtime toward achieving this objective.

A focus on food safety is also driving bakeries to address equipment challenges in terms of prevention of ingredient dust explosion, separation of possible allergens, ergonomics for the benefit of the users, and concerns over material handling. In addition, they are also adopting advanced technologies to address the challenges associated with packaging, storage, and distribution.

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