CO2 Mitigation through Biofuels in the Transport Sector. Status and Perspevtives

Institution:  IFEU – Institute for Energy and Environmental Research Heidelberg, Germany
Authors:  
Dr. Markus Quirin
Dipl.-Phys. Ing. Sven O. Gärtner < sven.gaertner@ifeu.de >
Dr. Martin Pehnt < martin.pehnt@ifeu.de >
Dr. Guido A. Reinhardt (project leader) < guido.reinhardt@ifeu.de >
Publication: 2004   

Executive Summary

Many studies have been conducted world-wide to examine the environmental impact of biofuels for transportation and estimate their cost and quantity potential. These studies have at times shown considerable differences in the findings and conclusions. In order to obtain an overview which identifies the strengths and weaknesses of the available studies and to determine further research needs, the Research Association for Combustion Engines FVV commissioned the IFEU Institute Heidelberg to conduct the present study. FVV and the Union for the Promotion of Oil and Protein Plants UFOP supported this research actively. This study analyses and compares all international, publicly accessible publications about all biofuels for transportation currently used (e.g. biodiesel and bioethanol as well as those potential future biofuels like BTL). More than 800 studies are taken into account. From these, 63 studies satisfy the criteria for detailed analyses, leading to the valuation of 109 energy and CO2 balances of various biofuels, which are compared either to conventional fuels or other biofuels. In most cases the complete life-cycles of the fuels, from production to consumption, are considered.

The findings of energy and greenhouse gas balances of biofuels, as well as their further environmental impacts and costs estimations vary greatly. This is mainly a result of the different assumptions made regarding the cultivation, the conversion or valuation of the co-products.

Ecological Impacts. Biofuels for transportation show both ecological advantages and disadvantages compared to fossil fuels. The advantages of biofuels include their contribution in conserving fossil resources, and the reduction of greenhouse effect since biofuels are more favourable in energy balance and greenhouse gas balance as compared to fossil fuels. A comparison among various biofuels demonstrates that ETBE shows advantages in energy balance and greenhouse gas balances over other biofuels regarding area related consideration. Bioethanol scores better or worse in dependency on raw material than biodiesel. When same system boundaries are assumed, biodiesel shows advantages compared to vegetable oil. The advantages of a few biofuels are not found in all geographical areas. For example, the bioethanol production from sugar cane is only limited to the tropical climatic conditions. Biofuels from waste materials (e.g. BTL) can be evaluated only if alternative usages of the waste are taken into consideration. This has been ignored in the studies hitherto available. Disadvantages of biofuels from energy crops are the higher level of eutrophication, acidification and ozone depletion associated with their use, due to the nitrogen compounds from agricultural production. No statement of clear tendency can be made for acidification and eutrophication regarding biofuels from waste materials.

A decision based on ecological considerations should take the individual advantages and disadvantages of the biofuels into account. When the conservation of fossil resources and the reduction of greenhouse effect are assigned as the highest priority, biofuels will be considered as favourable. The disadvantages are less dramatic and do not tip the balance of a general overall positive evaluation. The ecological differences between biofuels and fossil fuels will also not change drastically in the future. The advantages of the currently used biofuels will probably increase as compared to conventional fuels.

Costs. The production costs of biofuels for transportation are generally higher than those of conventional fuels. Accounting on the national level, not discussed here, could reverse this assessment. The comparison of the direct costs is determined by many economic and social external factors. The production costs of fossil fuels are dependent upon the world oil price and its fluctuations. The production costs of biofuels vary according to the national agricultural subsidisation and different state-specific personal costs and transportation costs. The range of estimates from these factors is so wide and the uncertainly is so large that no serious or reliable ranking among the biofuels can be made based on the available literature. The discussions regarding future costs also tend to be speculative.

Even in the present biofuels can be produced cheaper than fossil fuels under certain conditions. The production of biodiesel from recycled cooking oil serves as an example.

Quantity Potential. The potential of biofuels production is limited. While the annual produced biomass in the world could theoretically provide our total fuel demand, there are restrictions from other competing land use (food production, natural conservation, sustainable agriculture) and usages (biomass for material uses, source of bioenergy for power and heat production). In this way, competing land use alone reduces the usable potential in Germany to just a few percent of the fuel market. A reliable quantification for the EU or the world is still not available. Such limitations do not apply to the usage of biomass from waste material.

The availability and the efficiency of new production technologies is a determining factor of the quantity potential. These include the technology for BTL, ethanol from lignocellulose or for bio-hydrogen. However, with our present knowledge, it is impossible to predict when and which technologies will become available.

Further research need. Overall, there is a considerable need for further research on biofuels for transportation. There is still a paucity of publications about the energy and greenhouse gas balances of many biofuels such as biodiesel from palm oil and jatropha. With respect to DME, Methanol, and BTL, studies cover only one conversion path. The knowledge gap is even larger in the area of life cycle assessments. For instance, there is a lack of studies on many conversion routes such as in the area of BTL. Detail examinations are missing in many important individual studies, such as those on bioethanol or the motor emissions of biofuels in the most modern motor concepts.

Similar to the need to examine the direct costs of the various aspects in more detail, further studies about the potentials estimations in consideration of specific land use and competing usage for reference areas such as EU or the world should be conducted.

By way of summation and simplification, biofuels for transportation offer ecological advantages in resource conservation and climate protection as compared to fossil fuels. These advantages out-weigh the disadvantages in contributing to acidification, eutrophication, and ozone depletion. Biofuels are in general more expensive to produce - national accounting or social effects are not considered here. Due to competing land use and biomass usage, biofuels from agricultural biomass can probably only substitute a small portion of fossil fuels. The production of innovative biofuels like BTL calls for new technologies.