Sugar processing plants and energy efficiency
Although sustainable development has become a fashionable buzz word for many manufacturers, efforts made by the sugar sector over many years underline its awareness of the need to translate this desire into practical actions.
The first agri-food manufacturing site in France to benefit from environmental management ISO 14001 certification was a sugar processing plant. Based on its proactive approach, the awarding of ISO certification reveals the sugar beet sector’s long-term commitment to protecting the planet. For some ten years, from one end of the production chain to the other, farmers and manufacturers have made a major effort to limit the environmental impact of the sector’s activities.
The farming methods used by sugar beet farmers have enabled them to control and considerably reduce the need for nitrogen inputs and the use of plant care or irrigation products. The widespread use of “integrated” agricultural techniques in sugar production in France provides consumers with a solid guarantee with regards to the impact of beet farming practices on product quality and respect for the environment.
...and sustainable farming
The growing of sugar beets forms part of a sustainable development approach for several reasons:
- The plant forms part of a successive rotation of crops that vary from year to year. What are the benefits of rotation? It helps break the cycle of pests, disease and weeds and promotes the disappearance of insects and pests harmful to crops in general. It is said that the “soil retains the memory of the beet”.
- Thanks to its very deep root system, the beet acts as a “trap” for nitrogen, which it captures up to 15 metres underground, thereby reducing nitrate contamination.
- Beets also have a significant capacity to entrap carbon dioxide and, in summer, it is the only plant that remains in the fields to perform this function.
- Another positive contribution to the conservation of the natural environment is its wide leaf coverage, which helps preserve wildlife diversity. Beet crops provide a home to a large number of insects. For vertebrates, beets are particularly useful in autumn when other crops, except corn, have already been harvested.
- Lastly, it provides a major input of organic matter into the soil (50 tonnes of leaves are reintegrated into the soil for each hectare planted)
The sugar beet sector
Energy consumption per tonne of sugar beet has been almost halved in just forty years. The extraction of sugar - a dry product - from a humid plant (the beet contains 85% water) is, by its very nature, a relatively “energy-hungry” process, given the need to produce a high level of heat for the evaporation stage, leading to the production of sugar crystals. This has led manufacturers to redouble their efforts to achieve significant energy savings.
Engineering to save energy
A major French industrial group has developed a new process to reduce its energy consumption. In fact, an average fuel equivalent of 17.3 kg was needed to process a tonne of sugar beet, while the most efficient sugar processing plant used only 15 kg, and another used 18.4 kg. Following a major investment programme, the average fuel equivalent is now 15.7 kg and will, in the short term, drop under 15 kg. The group’s natural gas consumption fell by 13%.
How? Using hot water, sourced from end-of-process evaporation, to reinject it at the start of the cycle, avoiding the need to produce energy to reheat beets entering the process. At the same time, sugar juice, containing 85% water, are brought to boil several times to evaporate the water. The steam obtained is recovered to reheat the juice again, thereby reducing the energy required at the concentrate phase.
Reducing and recovering waste, optimising transport
The CO2 emissions of sugar processing plants, correlated to b, have been reduced proportionally over the same period. The use of gas rather than fuel or coal improved the carbon footprint, as did the use of condensation boilers, which burn condensates rather than emitting them into the air. In addition, all sugar processing plants produce their own electricity via one or more turboalternators powered by steam emitted by the processing operation.
Water, a precious resource
The high levels of water contained in sugar beets (85%) means that sugar processing plants have an overall water surplus. It is recycled increasingly through use in the various stages of the process (washing, diffusion, etc.). As a result, sugar processing plants limit their consumption of “new” water to a strict minimum.
Once again, the figures speak volumes: one sugar processing plant has achieved a tenfold reduction in its consumption of “new” water in just five years. The surplus residuary water is treated, stored and allowed to settle. It can be used for manure irrigation systems on farm land. At the same time, soil recovered following beet washing is returned to the land, contributing to the preservation of cultivated farm land.
Reducing road traffic
Lastly, the use of new, high-capacity lorries, led to a 15% reduction in supply-related road traffic and the emergence of a new generation of agricultural machinery, “lifters”, which pre-wash beets in the field, significantly reducing soil tare and, as a consequence, total transported volumes.
These initiatives cumulatively reduced the carbon footprint of the process of transferring sugar from the plant to consumers’ tables.