Turning sugar cane into ethanol (accessible)

From field to mill

Mechanical harvesters cut the cane into small pieces during the harvest.

Trucks bring in sugar cane to the processing mill.

Each truck is weighed to check how much cane it is delivering. Samples are removed to test the quality of the cane.

• Raízen harvests sugar cane with mechanical harvesters on around 64% of its land flat enough for the machines.
• Sugar cane must be processed as soon as possible to avoid its sugar content deteriorating. Most cane is delivered within 24 hours of harvesting.
• One tonne of sugar cane produces around 85 litres of ethanol.

Unloading

The truck unloads the cane onto conveyor belts that carry the cane to the crushing system.

Raízen has the capacity to crush around 62 million tonnes of cane each year.

Milling

A series of rollers crush the chopped cane and the juice flows out.

Cane fibre, called bagasse, goes to boilers to be burned.

The heat turns water into high pressure steam for electricity.

• Electricity from bagasse in the ethanol industry already meets 3% of Brazil’s demand and this is expected to rise to 15% by 2020.

Mixing and filtering

The juice is heated and sulphur, lime and thickener are added. 

The mixture is pumped to rotating filters that separate the juice from most impurities.

These form a crumbly residue, known as filter cake, which is used as natural fertiliser on the fields.

The filtered juice passes through sieves that remove any remaining impurities. The pure juice then either goes to the evaporation process to make sugar or to the fermentation process to make ethanol.

• Mill managers decide how much sugar and ethanol to produce depending on demand.

Water and yeast are added to ferment the liquid.

• Brazilian motorists used over 22 million billion litres of ethanol in the crop year 2009-2010.

The fermented liquid, called beer, passes through centrifuges. The yeast is removed, treated and reused.

Distillation

The liquid flows through two distillation columns which heat it to remove water.

This produces hydrated ethanol which is blended with petrol for use as a transport fuel.

The liquid by-product called vinasse is sprayed onto fields as fertiliser.

• At the pump Brazilian motorists choose between pure ethanol and a petrol ethanol blend.

Some liquid flows into a third distillation column that further heats the liquid to remove more water.

This produces anhydrous ethanol which is used in its pure form as a transport fuel in specially adapted cars known as flex fuel.

• The efficient industrial mills process sugarcane into ethanol in around 12-15 hours.

Storage

The ethanol flows into tanks to be stored and then transported to the market.

• Raízen produces more than 2 billion litres of ethanol each year. It sells fuel to customers at its 4,500 Shell-branded service stations across Brazil.