Ethanol from wheat
Order Description
1) Choose the process ‘Ethanol from wheat (straw CHP)’ and make a diagram showing the production pathway assessed including inputs, outputs and by-products including all the different stages from crop production to filling station. Discuss different allocations.
2) In the Directive Annex V, 5 processes for producing ethanol from wheat are considered. The default values for GHG emission reductions are between 16 and 69%. Explain why? What is the difference between the different production pathways? Use the overview results in the different Excel sheets at the BIOGRACE GHG emissions data sheets.
3) Bioethanol may also be produced from corn. Which of these feedstocks gives the best result? – Use again the BIOGRACE GHG emissions data sheets.
4) For the process ‘Ethanol from wheat (straw CHP)’, calculate the GHG reduction if the wheat is grown organically, i.e., no agro- chemicals, grain yield reduced by 20% and diesel consumption increased by 10 % (approximations!). Discuss how organic fertilizer may be included in the calculations.
In the spreadsheet ”EROI student exercise” you will find data to do an EROI assessment of US corn ethanol. 1. Based on the spreadsheet: Make a SIMPLE diagram of the process that summarizes inputs and outputs from agricultural phase and biorefineryphase 2. Calculate how much energy is used in the agricultural phase and in the biorefineryphase (MJcommercialenergy/ha) 3. Calculate the EROI for the system: a) Without credit for co-products b) Allocation based on energy content
The minimum EROI for a modern society is according to Murphy and Hall (2009) 3:1 Try adjusting different parameters (e.g. yield, inputs) to achieve this EROI.
Discuss: Do you think that corn ethanol is a viable main energy source for a society? Is it renewable energy?
Based on the same spreadsheet: § Make an EROI for Production of Ethanol from Wheat (steam from natural gas CHP), as described in the spreadsheet, BioGrace_GHG_calculations § Use only the data available in that sheet Ø Be prepared to make assumptions for transport and energy use in biorefineryphase § Discuss criticallassumptions
