The drying of hops takes a lot of energy

Can hops be dried more cheaply?

Hops have to be dried immediately after harvest to prevent a deterioration in quality. Consequently, driers only operate during the harvest season of around 3 weeks in a year. This makes it difficult to identify energy saving measures that are cost effective. With increasing energy prices over the past few years, the department of agriculture of the Alsace region in France decided to revisit the question of energy saving measures and tasked us with investigating and evaluating the options.

We decided to consider the following measures:

• Automating the drying process to reduce the air temperature, volume flow rate and drying time as far as possible without impairing the quality of the finished product
• Replacing fossil fuel with wood chips, using a containerised system which can be employed elsewhere outside the harvest season
• Preheating the supply air to the kiln with heat recovered from the exhaust air
• Recirculating exhaust air into the kiln, to benefit from residual heat in the air
• The replacement of fossil-fuel heating systems with heat pumps
• Improved insulation of kilns

Of the options considered, automation of kilns, the replacement of fossil fuels with wood chips, and heat recovery from the exhaust air show promise under certain circumstances. The other measures were discarded as not worthwhile.

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