Sugar factories are real „energy guzzlers“ and have a correspondingly large CO2 footprint. But high emissions are also produced in the field and especially during transport. Reducing these costs a lot of money and will take years.
CO2 avoidance is a big buzzword. In reality, however, not everything can be realised so easily. Especially not with transport and energy-intensive products such as sugar beet. What is possible, what is unrealistic? The reduction or avoidance of CO2 emissions in the sugar production chain can be roughly divided into three areas: Production in the field, transport to the factory and processing in the factory.
Production in the field
In the field, it is primarily the use of nitrogenous fertilisers and the consumption of diesel that have a major impact on the CO2 balance. The amount of plant protection also plays a noticeable role. Nitrogen fertiliser can be produced from renewable energies, but it is expensive and so far uneconomical. ‘Green’ KAS costs around €100 per tonne more than KAS produced using natural gas - and it will not be until 2026 that enough product will be available to move from the pilot phase to large-scale use. And only if the customer is ultimately prepared to bear the additional costs. However, the effect on the CO2 footprint is considerable. Between 1.5 kg (urea) and 4 kg of CO2 (KAS) are produced per kg of nitrogen. Some of this is captured in the ammonia plants and reused for industrial purposes (beverages, preservation, technical purposes). However, the decisive factor for the CO2 footprint is the yield. Even if the beet is fertilised with 170 kg of nitrate-N, this amounts to only 7 to 8 kg of CO2 per tonne of beet.
Reducing diesel through alternative drives?
CO2 can be saved on diesel consumption, for example by reducing soil cultivation, but ultimately CO2-neutral beet cultivation requires new drive technologies in tractors and, above all, beet harvesters. Fuel cells, batteries or biogenic ethanol, HVO or methane are certainly the most technically feasible options. But even these drive systems are not widely available, nor are the necessary fuels. For the time being, diesel will remain the energy source on farms. Assuming 150 litres of diesel and 90 tonnes of beet per hectare using conventional production technology, this equates to 4 kg of CO2 emissions per tonne of beet. However, this simple example calculation shows the potential that lies hidden in the farms: stable and high yields are a guarantee for lower CO2 emissions. This is because 10% more yield automatically means 10% less CO2 released per tonne of beet.
Although crop protection products and their reduction play the smallest role of the emission sources mentioned, they are the easiest to reduce. The technology for selective applications or the electrically operated hoeing robot is available, but has not yet become widespread due to the high investment costs. After all, it is available.
Transport to the factory
The transport of beet does not play a major role in the overall balance, at least not on average for all beet delivered. At a factory distance of 50 km, which is about the average for all factories, this amounts to 5 kg CO2 per tonne of beet, i.e. approximately the same amount as diesel consumption in the field. The tide turns at long distances. For example, all organic beet from Nordzucker has to be transported to Schladen, and that from Südzucker to Rain am Lech. From Wetterau or Kraichgau or Franconia, this can mean a one-way journey of 300 or 200 kilometres to Rain - usually without return transport. With new lorries consuming 30 to 32 litres of diesel per 100 km, this quickly adds up to 16 kg of CO2 per tonne of beet. This means that ‘organic’ beet very quickly becomes environmentally harmful beet.
There is currently no alternative to lorries
The railway is definitely not an alternative, even if the route network were expanded and reliable. This is because there is simply a lack of capacity for freight wagons, locomotives and personnel for a seasonal business lasting four months. In addition, broken freight with reloading (hire - lorry - rail) causes additional costs and ties up personnel. Trucks with electric or other environmentally friendly drives are conceivable, but these drive concepts must be suitable for a 12-month utilisation period, not just a 4-month campaign. In addition, the drives must be suitable for use on the road. With methane, this would be easily conceivable and the engines could also be converted, but the availability of biogenic methane has so far been lacking.
Processing in the factory
The biggest levers for reducing CO2 emissions are in the factories. All German factories together emit around 1.8 million tonnes of CO2. With around 29 million tonnes of sugar beet, this amounts to 62 kg of CO2 per tonne of beet. However, savings can also be realised on an industrial scale. The first step in many factories is to replace coal or oil with gas. Nordzucker, for example, wants to realise this by 2030 at the latest. This could be biogas, such as that produced by the plant in Anklam from pressed pulp, or from external biogas plants, as Nordzucker will use for its two plants in Denmark. However, the biogas plants must have a minimum size of 4 MW for the processing of the gas to be worthwhile. However, there are strong competitors for this gas in terms of demand: the transport sector is looking for precisely this gas, and the population is prepared to pay significantly higher prices for refuelling cars or bus fleets than the sugar factories can.
Electrification or external procurement of steam from neighbouring industrial plants
If incineration plants or other heat generators are located near the factories, external steam can also be sourced. There are examples of this in Sweden and the oil mill in Mannheim. The sugar factories can also be electrified to a greater extent, although this has its limits, as the ratio of steam to electricity generation is difficult to change. In addition, the power connections of the sugar factories are not always designed to draw all the energy in the form of electricity.
Nevertheless, there are possibilities for this and they are being realised. For example, Nordzucker has put the first vapour recompression system into operation at its Nordstemmen factory. This involves compressing cooled vapour with compressors. Compression leads to an increase in the temperature of the vapour so that it can be used again. This is one way of replacing thermal energy with electricity. But many plants need to be converted.
CO2-neutral from 2045?
The drying of the wood chips can also be optimised in terms of energy by using evaporation dryers. However, the necessary investments cannot be realised in just a few years and are also not financially viable in the short term. The sugar industry's updated ‘roadmap’ therefore envisages CO2-neutral sugar production in line with legal requirements from 2045 and puts the costs at between € 1.2 and 2.8 billion, depending on the technology used.
Nordzucker and Südzucker have committed to reducing CO2 emissions from their own production and purchased energy by half by 2030. Cosun (Anklam) and Pfeifer&Langen want to base their reduction targets on scientific criteria, but this is likely to be of a comparable order of magnitude.