Energianalys av etanolproduktion

Energy analysis of ethanol production

Paulsson, Per (2007) Energianalys av etanolproduktion. Dept. of Biometry and Engineering, SLU. Examensarbete (SLU, Institutionen för biometri och teknik) vol. 2007:03.

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Abstract

In this thesis an energy analysis of ethanol production at the ethanol plant of Lantmännen Agroetanol in Norrköping has been performed. The ethanol plant has been studied in combination with Händelöverket, the combined heat and power plant which provides the ethanol process with steam. The purpose of this study was to determine the energy consumption for the whole production chain from grain to ethanol. The analysis has included the energy consumption for cultivation of grain, production of chemicals, the production chain for wood chips, the steam production and the ethanol plant. The grain and wood chips are both considered raw materials there for the energy content in these are not included as energy input in the system. Instead the help energy to produce these two raw materials have been included as input of energy.

The result from the study is presented as an energy balance, defined as the energy content for the ethanol divided by the total energy input for production of the ethanol. The energy balance has shown to be 2,6 if economic allocation is used. This means that there is more energy produced in form of ethanol than has been used to produce the ethanol. It is possible to make the production of ethanol more energy efficient by producing electricity with a steam turbine before the steam is used in the ethanol plant. If this is done the energy balance will increase to 3,1.

An alternative production system for ethanol has also been studied, in which DDGS (distillers dried grains with solubles) and DWG (distillers wet grain) is used as fuel for steam and electricity production. This system has less quantity of byproducts since most of the DDGS is used as fuel instead of animal feed as in the earlier studied system. The energy balance for this system showed to be 2,9 or 3,1 for economic allocation depending on if DWG or DDGS is used as fuel.