Bakeries can save energy through sustainable design features: Use more natural light in your production facility. Prefer the best practices to minimize compressed air losses to reduce energy consumption. Gain the heat back from ovens. Design ventilation in production areas to reduce possible contamination. These are just a few of the energy saving opportunities to be taken into consideration.
The bakery sector is extremely competitive and main drivers are inevitably product, price and quality. So in times of low margins and growing environmental responsibility, the industry is heavily focused on reducing costs by making operations and procurement more efficient. That means energy, and so carbon efficiency, is of increasing interest to the sector. There is now greater interest in energy efficiency within the sector, because of compliance requirements, cost control and, more recently, corporate responsibility. Investments in energy efficiency are a sound and key business strategy in today's manufacturing environment
All industrial plants should make energy management a priority, and take action by implementing an organization-wide energy management program. With energy efficiency, you get what you pay for. It is critical to recognize that energy efficient equipment and products may cost the company more initially but that the lasting savings gained from their use will save more money over time.
Successful energy management involves more than just installing a few energy-efficient technologies. It involves establishing a committed company-wide program to manage energy continuously as a function of your business. It’s an ongoing process that involves: understanding your energy use, setting goals, implementing good operational and maintenance practices, making behavioral changes, tracking and benchmarking energy use, and involving every employee.
In order to improve energy efficiency and reduce the operational costs of a baking facility, several operations should be assessed. Firstly, baking plants use a number of cross-cutting equipment such as motors, air-compressors and boilers which consume a significant amount of energy and thus, need to be efficiently operated and properly maintained. Secondly, another area that requires attention is the efficient manufacture of baking products. The optimization of production processes and practices in baking along with the use of efficient equipment can result in significant cost savings.
There are many simple options for saving energy in an industrial bakery. Companies that apply a few basic principles to energy management can achieve substantial savings. These principles can be applied by any company, regardless of size, that is committed to reducing energy use.
- Turn-off campaigns for conveyors.
- Shutdown procedures for major plant, e.g. provers, ovens, coolers.
- Compressed air management practices.
- More efficient air compressor plant including variable speed drive units.
- Reduction of compressed air leakage rate.
- High-efficiency lighting applications – the installation of T5 fluorescent high-frequency systems in productions areas.
- Occupancy control of lights in lower use areas such as, offices, meeting rooms, stores and plant rooms.
- Monitoring and targeting programs.
- Improved insulation of major process plant such as ovens and provers.
- Reducing the amount of air entering dispatch areas – by improving seals and air curtains.
- Space heating control improvements – office wet systems temperature compensation and boiler optimization; process area convector heater advanced controls.
- Variable speed drives (VSDs) on bakery ventilation systems.
- Improved insulation of steam and chilled water distribution systems.
- Energy awareness campaigns.
The most important energy sources in a bakery are natural gas and electricity. Natural gas is mostly consumed in the ovens, which consumes around 70-80% of the total gas. Other consumers of natural gas are: Steam production, area heating, crate washers, etc.
The main consumers of electricity are: Cooling of the process, air-conditioning, dough preparation, lighting, compressed air.
Hereby some easy measures for saving energy in the bakery have been presented. These options are randomly presented and can be used as practical guideline which can be directly implemented in your own company.
Almost every bakery has a compressed air installation. Reducing the pressure with 1 bar saves around 7% of the total electricity consumption of the compressed air installation.
Leakage losses consume mostly up to 30% of the total compressed air consumption. A puncture of 1 mm spoils yearly around 3.000 kWh.
In many industrial bakeries a steam installation is used. Although the installations are relative small (mostly smaller than 1.000 kg/hr) there are feasible options for energy saving.
The first question is: Do you really need steam? Most of the time steam is only used for transportation of energy, which is relative inefficient. There are, for example, more efficient options than using steam for area or water heating.
Make sure insulation of piping and fittings is up to date. A fitting of DN 50(2”) loses 4.000 kWh extra when it is not insulated. The return on investment is less than a year.
Configuration of excess air for burner
Each burner needs an amount of air for good natural gas combustion. Too much excess air gives a lower efficiency of the steam boiler. Your boiler installer can help you with the right set-up.
Energy efficient lighting is an issue everywhere. Switch off lighting wherever possible. Alert your employers and consider the installation of day light and motion sensors.
Mechanical refrigeration is applied for product cooling, chilled process water, room conditioning.
Check the suction and discharge pressure of your refrigeration installation. For an efficient installation, the pressure difference must be as small as possible. Lowering of the discharge pressure of 1°C gives an efficiency improvement of 2%.
Reduction of base load
Switch off equipment, lighting, compressed air, boilers, etc. when there is no production. Many companies can save energy with this simple measure.
To gain more insight in the energy consumption, it is useful to collect meter readings. By relating energy consumption to f.e. production numbers, it is easy to see deviation in the key performance numbers. With the key performance numbers, targets can be made to achieve energy saving.
YOU CAN MAKE BETTER USE OF WASTE HEAT
Useful consumption of waste heat
An important part of the energy consumed becomes available as waste heat. In several cases, this heat can easily be recovered and reused directly for various purposes. However, more often the temperature level is too low to use the heat directly. In this case a heat pump can increase the temperature.
Publicly a heat pump is mostly described as a “reversed refrigerator”. A refrigerator cools the content and the heat is lost via the back side (condenser) of the refrigerator. A heat pump cools down the waste heat source and the condenser heat, increased in temperature, gets a useful application. The heat pump brings the heat from a ‘useless’ temperature to a more usable temperature.
The efficiency of the heat pump is denoted by its COP (coefficient of performance), defined as the ratio of total heat delivered by the heat pump to the amount of electricity needed to drive the heat pump. The COP depends on the type and application of the heat pump, but is most of the time more than 4, which means that 1 kW electricity is needed to generate 4 kW of heat.
Using the heat of the refrigeration installation
By adding an additional compressor on the refrigeration system, the waste heat can be upgraded to maximum of 80°C, which can be used in the production process. There are many more application for heat pumps. But it is important to keep in mind that a heat pump is a way to achieve the goal and it is not a goal itself. First it is important to find ways to directly exchange heat. If this can be achieved, there is no need for a heat pump.
By working closely with equipment suppliers (where appropriate), bakeries should consider:
· Increasing oven combustion efficiency by improving maintenance operations and measurements.
· Modulating oven burner firing rate to control temperature more effectively, rather than high fire/low fire control.
- · Reducing hot oven gas extraction from ovens through optimising damper settings.
· Using direct drive or non-slip drive on fans.
- · Balancing oven airflows to reduce losses.
· A phased manual shut down of oven burners during product gaps and shutdowns.
- · Automatic switch off or conversion to low fire of oven burners during gapping and shutdown.
· Manual shut down/ turn down of oven fans during gapping.
SOME INDIVIDUAL MEASURES REDUCE ENERGY COSTS
- · Improved prover, oven and cooler shutdown during production gaps.
- · Reviewing their production baking process schedule.
When selecting an oven to install or looking to upgrade an existing oven, consider a system that is flexible in what products it can produce. Increasing the amount of one product made or diversifying the product line to include various baked goods can increase the overall energy intensity of a bakery. By producing more than one product bakeries can increase production and minimize downtime. Even when an oven is purchased to produce only one type of product the oven should be designed to produce any foreseeable variations of that particular product. These design considerations typically focus on advanced controls and building an appropriate mix of convection and direct-fired modules into the oven.
Product flexibility can also be accomplished by using a multilevel oven. Multilevel ovens offer the potential to bake multiple products at once, increasing the diversity of a bakery as well as throughput. These ovens can be controlled so that different levels within the over are set to different temperatures, air flows, and humidity levels. As production demands change the number of levels set to bake a single product can be changed, adapting to the needs of the bakery. As ovens represent a potentially five or ten year investment for a bakery, maximizing product flexibility will help bakeries easily transition to new products in an efficient manner.
Slicing and Packaging
Increasing plant throughput and decreasing stoppages can indirectly reduce energy consumption. Slicing and packaging operations tend to be a bottleneck in production. These operations need to run smoothly and consistently to reduce the potential for plant shutdown and to increase production rates. Even modifying existing slicing and bagging systems with low air nozzles can save energy and has a short two to four month payback period.
Keep in mind that although the expected savings associated with some of the individual measures may be relatively small, their cumulative effect across an entire facility may be quite large. Many measures have relatively short payback periods and are therefore attractive economic investments on their own. The degree to which these measures are implemented will vary among plants and end uses, but continuous evaluation of your facility’s energy profile will help to identify further cost savings over time.