Bioenergy in bread/biscuits/cakes production
Bakeries are one of the most important and largest industry sector in Germany and Europe. Bakeries can also be characterised by a relatively high energy demand, as the baking process requires high quantities of heat and electricity. The thermal energy needed for the operation of ovens, with 50 to 80%, comprises the lion share on the energy demand. Above all the heat required for the baking process at a temperature level of about 180-360°C plays an important role in the energy supply structure of a typical bakery. Figure 1 shows the distribution of the energy consumption for a typical baking facility .
Figure 1: Energy consumption distribution of bakeries 
The energy costs comprise a relatively low share of the total cost of the total production cost of a baking facility. Therefore, energy savings receive a relatively little attention with respect to the optimisation potential of the baking process. However, due to the increasing cost of energy and due to ecological concerns, the need for efficient energy management in bakeries has been recognised. Because energy costs play a subordinate role in the expenditure structure of small and medium scale enterprises (SME), there can be a lack of motivation with respect to energy efficient enhancement of the production processes. Nevertheless, studies has shown that the energy demand of bakeries may be reduced by 32% and the greenhouse gas emissions could be reduced by 48%. In addition to the reduction of energy demand, a significant decrease in the water consumption and amount of waste generated could be achieved. There is also a strong potential for the utilisation of renewable energy sources for increased utilisation of renewable energy sources to cover the energy demand of the baking process in order to reduce the environmental impact of baking industry .
One of the most important measures, which can be applied in order to improve the ecological balance of the baking process, is the increased use of renewable energy sources to cover the energy demand. The heat demand, which plays the most important role in the energy demand of a baking factory, could be covered by biomass. There are many ovens available on the market, which can be fired by wood pellets or wood scraps. Additionally the production wastes from the baking process are a valuable fuel with neutral CO2 balance and can be used to feed the biomass burner, which generates heat for the production process . Pellet burners of the Manufacturer Gillet are applicable at small backing factories with a heat demand under 100 kW. The pellet burner are installed on the side of the ovens in order to generate a horizontal flame in the combustion chamber. Baking ovens, which are usually fired with natural gas or heating oil have to be retrofitted in order to use wood pellets or wood chips as fuel. Generally, wood pellets are more suitable as a fuel for baking facilities because of the high quality of wood pellets, which makes them easier to handle then wood chips. Due to the fact that the heat consumption of the ovens has an 80% fraction of the total heat demand of a baking factory, there is a considerable potential for greenhouse gas emission reduction that can be mobilised by utilisation of biomass-fired ovens. In this way, the main share of the energy demand of the baking process can be covered environmentally-friendly and efficiently .
Figure 2: Baking oven with a pellet burner
In larger bakeries, the installation of a central biomass boiler is more economical. The heat in such system is distributed from the central boiler to the single ovens via a heating circuit where thermal oil is used as the heat transport agent. Such a system configuration is interesting for baking facilities with a baking surface of more than 60 square meters .
Figure 3: Schematic drawing of a bakery with central biomass boiler
Although the energy cost are only a small portion of cost of the baking process, the installation of biomass-fired boilers is economically feasible. Considering the fact that biomass boilers can use production waste material as a fuel, the installation of a 150 kW thermal oil biomass boiler can be amortised within 5 years. Another important advantage is the possibility to reduce CO2 emissions by 103 tonnes per year by utilisation of a 150 kW biomass-fired heat source .
- www.energieexperten.org, Baking industry and confection industry discussion about the conflict between fuels and bread (in German), Apr. 2011.
- Concerto Report: TREN/06/FP7EN/239285/”SOLUTION”, Optimisation of SME-Area energy system supplied by bio-boiler/gasifier CHP, Oktober 2010.
- Energy management practices in SME – case study of a bakery in Germany, Energy Conversion and Management, 44 (2003), pp. 945-959.
- www.energieagentur.nrw.de, Structure of the energy demand - bakeries, 2011 (in German).
- Federal Environmental Agency, Setting up of an eco-bakery on the base of an integral conception, Sept 2005 (in German).
- www.industry.gov.au/energybestpractice, Achieving results in the bread baking sector, Juni 2003.
- Infomaterial Fa. MVRG, BioTherm – biomass boiler, 2011 (in German).
- http://www.ihr-bäcker-schüren.de, 100 % quality - 91 % CO2-reduction - 50 % energy demand reduction, 2011 (in German).
- Biobaking technology, Innovationen aus dem Handwerk für das Handwerk, 134 (2009), pp. 15 (in German).
- http://bakerybazar.blogspot.com, Energy saving projects implemented by UK bakers, 2011.