Final Program EXPRES 2012 - Conferences

iodiesel production facility with annual productioncapacity of 100,000 mt of biodiesel. Thetransesterification process is performed with methanol inthe presence of sodium methoxide as an alkali catalyst.The material and energy inputs of the process aredescribed in [12]. The emissions to air during thetransesterification process were assumed to be negligible.After the transesterification process biodiesel istransported to the final consumer located 25 km away.Tab. 1 gives an overview of processes included in theLCI of biodiesel with specification of material and energyinputs and references to data sources used.LCI assumptionsAllocation procedure. The production of biodieselgenerates by-products like rape straw, rape meal andglycerol (Fig. 1). The purpose of allocation is todetermine how a particular environmental burden, e.g.CO 2 emission, should be shared amongst the biodieseland the by-products. The allocation procedure adopted inthis study is based on economic allocation, i.e. the overallenvironmental burden of the system is shared amongstbiodiesel and by-products proportionally to their share inthe overall revenue of the system. The market prices usedto calculate the revenues from biodiesel and co-productsare as follows: 265 EUR/mt of raw rapeseed, 28 EUR/mtof rape straw, 730 EUR/mt of refined oil, 170 EUR/mt ofrape meal, 900 EUR/mt of biodiesel, and 80 EUR/mt ofglycerol.Accounting for CO 2 absorbed by the plant. A certainamount of carbon from the air is absorbed by the plantduring the process of photosynthesis. This carbon can beaccounted for as a positive externality and eventuallysubtracted from the overall external costs of biodieselproduction chain. According to [19] the carbon content ofraw rapeseed grain is 58.4% on a mass basis. Under theassumption that all of the carbon is absorbed from theatmosphere it can be calculated that during the productionof 2,554 kg raw rapeseed grain 1,491 kg of carbon isabsorbed, corresponding to 5,469 kg of CO 2 . Of the 1,491kg of carbon taken up by the rapeseed plants in theagriculture stage, we take credit for only 736 kg ofcarbon; which equals the biomass-derived carbon contentof 1,000 kg biodiesel fuel [3]. This is equivalent to 2,700kg of CO 2 removed from the atmosphere for every mt ofbiodiesel produced. The remaining uptake of CO 2 isassociated with by-products in the production chain ofbiodiesel (i.e. rapeseed meal and glycerine). We did notfeel it was appropriate to take credit for this carbon.Stage in theproduction chainRapeseed cultivationand harvestingDrying of therapeseed grainPressing and solventextractionTABLE I.MATERIAL AND ENERGY INPUTS IN THE PRODUCTION CHAIN OF BIODIESELInputs of material and energy Source ofSource of airborne emissiondata onUnitQuantity emissionsProduction and use of ammonium nitrate fertilizer kg N/ha 140 Ref. [4]Production of triple superphosphate fertilizer kg P 2O 5/ha 40 Ref. [4]Production of potassium chloride fertilizer kg K 2O/ha 80 Ref. [4]Production of pesticides kg/ha 1.25 Ref. [4]Production of sowing seeds kg/ha 5 Ref. [4]Production and combustion of diesel fuel in agricultural machinery MJ/ha 3,228 Ref. [6, 7]Production of lubrication oil MJ/ha 322 Ref. [6]Transport of rapeseed grain to dryer via diesel truck tkm/ha 173 Ref. [9]Production and combustion of light fuel oil for process heating MJ/mt of dried seed 260 Ref. [6]Production of electricity kWh/mt of dried seed 2.7 Ref. [13]Transport of dried grain to oil mill via diesel truck tkm/mt of dried seed 75 Ref. [9]Light fuel oil production and combustion in steam boiler kg/mt of crude oil 43 Ref. [6]Production of electricity MJ/mt of crude oil 419 Ref. [13]Production of hexane kg/mt of crude oil 1.19 Ref. [14]Crude oil refining Production of electricity MJ/mt of refined oil 104 Ref. [13]Light fuel oil production and combustion in steam boiler kg/mt of refined oil 6.2 Ref. [6]Production of phosphoric acid (85% in H2O) kg/mt of refined oil 0.8 Ref. [15]Production of sodium hydroxide (50% in H2O) kg/mt of refined oil 2.1 Ref. [15]Production of sulphuric acid (100%) kg/mt of refined oil 1.9 Ref. [15]Production and consumption of bentonite (clay) kg/mt of refined oil 9 Ref. [16]Transport of refined oil to biodiesel plant via diesel truck tkm/mt of refined oil 1 Ref. [9]Transesterification ofrefined oil intobiodieselProduction of electricity kWh/mt of biodiesel 12 Ref. [13]Natural gas production and combustion in industrial boiler MJ/mt of biodiesel 1,236 Ref. [17]Production of sodium methoxide (100%) kg/mt of biodiesel 5.0 Ref. [18]Production of sodium hydroxide (50% in H2O) kg/mt of biodiesel 1.5 Ref. [15]Production of hydrochloric acid (36% in H2O) kg/mt of biodiesel 10 Ref. [14]Production of methanol kg/mt of biodiesel 96 Ref. [15]Transport of biodiesel to filling station via diesel truck tkm/mt of biodiesel 50 Ref. [9]73