Globally and in the EU, the transport sector is responsible for 30% of total energy consumption. Much work is being done in the EU to increase the use of biofuels.
Life cycle assessment
Then the environmental burden corresponding to product B2 is subtracted from the system under investigation and the resulting system corresponds to the environmental burden for product A. In studies related to the production of RME and ethanol: product A corresponds to RME, product B1 to rapeseed meal and product B2 to soy meal; or product B1 corresponds to process glycerine and product B2 to fossil glycerine; or product A corresponds to ethanol fuel, product B1 to distiller's waste and product B2 to soybean meal.
Objectives
Gärtner & Reinhardt (2001) and Reinhardt & Gärtner (2002) performed an LCA study for small-scale RME production, but their results are only valid for German conditions.
Extraction of rapeseed oil
Materials and methods Oil extraction
Akaike's information criterion was used to determine whether the correlation factor should be retained in the model. A second time factor for each adjustment was also entered into the model, starting with the number 1 for the first sample in each adjustment and ending normally with the number 5 for the last sample in each adjustment.
Results
Oil extraction capacity and efficiency, nozzles with a common channel for press nozzles with an adjustable spacer, with different screw rotation speed for different types of nozzles. Settings where the pressure screw was moved forward with the setting spacer had greater oil extraction efficiency than without the spacer (Figure 5).
Environmental assessment of RME and ethanol fuel production
Ethanol production from wheat can be divided into three main processes (Fig. 7): fermentation during which crude ethanol is produced; distillation during which water is removed from raw ethanol until the ethanol content is 95% (by volume); and drying of stills (not carried out in medium and small scale plants). Data on physical and economic allocations during small-scale production of RME and ethanol fuel are presented in Table 2. Data on physical and economic allocations during small-scale production of RME and ethanol fuel.
The results for small-scale production of RME and ethanol fuel are described in Fig. The results for the small-scale system for production of ethanol fuel are described in Fig. The change in environmental impact and energy use for medium- and large-scale production of ethanol fuel compared to small-scale is shown in Tables 3-4.
Differences in environmental impacts and energy requirements for medium- and large-scale production of RME fuel and ethanol compared to small-scale production Factors of production Global warming potential.
Farm-produced bio-based motor fuels on organic farms
Important changes in the results were also observed when the ignition enhancer produced was of bio origin instead of fossil resource origin. When the produced ethanol fuel was used for cultivation and transportation in the studied system, GWP decreased by several percent. Difficulties arise when studying the cultivation of a single crop as each of the crops in the rotation in organic farming systems is affected by the cultivation of the other crops.
The electricity use was set at 6% of the energy in the feed gas and the methane loss was assumed to be 3% based on Persson (2003). However, the ignition improver added in the ethanol scenario was made from fossil feedstock.
Results Land use
CO2 emissions resulting from the use of the fuels were not taken into account because the CO2 was of renewable origin. Primary energy used and energy content of the fuel produced for the scenarios studied (GJ). allocated) Total (not . allocated) Energy in fuel produced. When the assigned values were compared, the more valuable byproducts of the RME scenario resulted in the RME value being clearly the lowest.
The potential environmental impacts of the fuel supply components of the studied scenarios are shown in Table 8. The impacts of the direct emissions from all tractor activities on the farm (use of all fuel produced) are shown in Table 9.
Discussion
Emissions from cultivation contributed significantly to the acidification potential for the RME and ethanol scenarios (Table 8), while the effect of fuel production alone was significant for the ethanol scenario. In fuel production, emissions for the ethanol scenario came from the burning of straw for heat and from the production of the ignition improver. Acidification emissions caused by fuel use (Table 9) are much higher for all fuels studied than the total corresponding emissions caused by the fuel supply system (Table 8).
The relatively high emissions of NOx during the utilization of the RME produced had a clear effect on the total potential acidification of this scenario. Nutrient leakage in each scenario was largely dependent on the area used for feedstock production.
Oil extraction
The potential eutrophication (Tables 8 and 9) caused by the studied scenarios was mostly due to nutrient losses from agricultural land and NOx emissions.
LCA methodology in general
Functional units and system boundaries
When comparing different fuels (Bernesson, 2004) the use of the fuels must be included in the system, because e.g. RME and ethanol fuel should be used in different engines with different emission characteristics and different engine efficiency. When plant sizes are compared, the production of the feedstock (canola for RME production and wheat for ethanol fuel production) can be excluded from the system if it is used with the same efficiency in all compared plant sizes.
This is the case when ethanol fuel is produced, but not when RME is produced, because oil recovery efficiency differs, as does land use efficiency. In other parts of Paper III, the production of wheat was included in the system because the cultivation provided important data for the study (e.g. the importance of synthetic fertilizers).
Allocation strategies
Thus, if the system is being studied at a higher system level and the impact of a particular change in overall fuel production on the end-use system is of interest, allocation with an extended system may be the fairest method. However, the disadvantage of this method is that changing the assumptions about the production of substitute products can have very significant effects on the results. The reason is that when rapeseed oil is used directly, there is no need for resources for transesterification and methanol production, etc.
The reason is that the by-product glycerine from RME production replaces glycerine of petroleum origin and a large burden on the environment. Extended system allocation may be the most appropriate allocation method when systems are studied from a general, more socially oriented perspective.
Effects on environmental load of plant sizes and fuel choice
For ethanol fuel production, the amount of soybeans and soybean meal replaced by distiller's waste was independent of plant size. During RME production, area yield varied greatly between GJ/ha rates for small, medium and large plants, respectively). For ethanol fuel production, GWP-, AP- (for physical distribution only) and EP emissions were lower than for RME production.
High POCP emissions and energy requirements during the production of ignition improvers, heat, and denaturants were the main reasons for the higher POCP emissions and energy requirements during ethanol fuel production. The higher energy demand also depended on the high demands on electricity during ethanol fuel production.
Data quality
Comparison with results from related studies
The soil emissions (NH3 and N2O) and SOx emissions were higher in the present study compared to the other studies. The energy consumed was the same in the present study and the studies conducted by Blinge et al. That study was similar to the present study, but it was conducted under German or Central European conditions.
In this study, extended system allocation is studied as an alternative allocation method. Most other emissions were higher in the present study compared to the other two studies, mainly due to the rather high emissions considered for heat (steam) production in the present study (Kaltschmitt & Reinhardt, 1997).
Comparison with use of fossil fuels
Economic considerations
These figures show that the RME can be produced profitably and that the ethanol fuel is close to profitable production in large plants. It may also be possible to profitably produce RME in medium-scale plants, as such plants reduce production costs by more than 30% compared to small-scale plants. Production of RME and ethanol in small farm scale plants cannot be recommended due to the high costs.
The simpler process for producing RME also makes this fuel more suitable as a rural fuel. This allows production of RME in medium and large-scale plants to be recommended.
Biofuels in organic farming
A more profitable solution could be for farmers to join together and set up a medium-sized plant and sell RME or rapeseed oil instead of seeds. The organic farming system (Paper IV) produced approximately halved GWP emissions compared to the conventional farming system studied (Papers II and III) for the production and use of RME fuel or ethanol. The reasons were to avoid the requirement for artificial fertilizers with their associated high emissions (Figure 10) and some emissions in the organic system (contribution IV) that were allocated to the straw side.
The production of RME includes well-proven technology suitable for use in farm-scale applications. If the higher production costs of such small plants could be accepted in organic farming systems, farm-scale RME production facilities could be recommended.
Reducing the environmental impact
However, the amount of methanol required to produce RME cannot be reduced in the same way because it is a product of the chemical reaction between rapeseed oil and methanol. In the future, there will be new processes for the entire production process of biomass from seed to usable energy supplied by vehicles, agricultural machinery, etc. They require fuel in the form of hydrogen gas or methanol with techniques currently in use, but research continues. the use of biogas (Ahrens & Weiland, 2003; Weiland, 2004) and ethanol (Baff, 2003) as alternative fuel sources for such cells.
It is possible to produce the hydrogen gas for the fuel cells from biomass using various methods. It is also possible to use syngas to produce methanol, dimethyl ether (DME) or Fischer-Tropsch fuel for use in internal combustion engines (General Motors Corporation et al., 2001; L-B-Systemtechnik, 2002).
Conclusions
Chalmers University of Technology, Department of Transport and Logistics and KFB-Swedish Transport and Communication Research Board, KFB-report 1997:5. Directive 2003/30/EC of the European Parliament and of the Council of 8 May 2003 on the promotion of the use of biofuels or other renewable fuels for transport. Swedish Environmental Protection Agency, Annex 13: Sweden's National GHG Inventory 2002. http://www.naturvardsverket.se/dokument/. fororen/utslapp/fcccdata/fccc2002.pdf.
Energetic and energetic analyzes of rapeseed oil methyl ester (RME) production under Swedish conditions. Contribution of working group I to the third assessment report of the Intergovernmental Panel on Climate Change [Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Dai, X., Maskell, K Cambridge, United Kingdom and New York, NY, USA.
Acknowledgements
