Study assesses pros and cons of alternative fuel technologies
[Date: 2007-07-25]
A number of alternative fuel technology options for road and air transport have been developed in recent years. While most of them have been extensively discussed, the information available is usually fragmented, being either too scientific or simplistic in its presentation, and generally not comparable. Now STOA, the European Parliament's Scientific Technology Options Assessment body, has published an inventory of 20 of the most promising options, which are clustered in five technologies: hydrogen and fuel cells, battery electric vehicles, hybrid technology, biofuels and natural gas. The inventory provides a comparative overview of the pros and cons of each of these technologies. Focusing primarily on road transport, the study starts by looking at hydrogen which, when combined with fuel cells, seems to be a promising technology alternative. However, some serious technological problems remain unsolved, including for instance questions concerning the performance of fuel cells, and the production of large amounts of 'clean' hydrogen. Recently, the only affordable way of large-scale hydrogen production has been via steam-reformation from natural gas. From a mid-term perspective, this route might support the market penetration of hydrogen and of fuel cells, notes the study. The crucial point is that, in this case, hydrogen would be derived from a fossil fuel source. Other routes are also being discussed, including the production of hydrogen from renewable sources (wind, photovoltaic, solar thermal, water) via electrolysis. This is often regarded as a kind of silver bullet since it enables close to zero emissions of greenhouse gases (GHG). 'But it is not clear if, at which time, and in which regions the production of hydrogen from renewable sources will be feasible at larger scales and at reasonable costs,' says the study. A 'clean' production of hydrogen from nuclear power is feasible as well, but the drawbacks here are the finiteness of uranium sources and the acceptance of the use of nuclear power. In terms of climate security, the study predicts that the coal route will only be suitable if it is combined with CO2 sequestration and storage (CSS). Assessing the use of hybrid technology, the study finds that this option offers the possibility to save energy and emissions by using established technologies and infrastructures. Whatever fuel and propulsion technology will be dominant in 20 to 30 years, the authors of the study predict that that hybrid technology will be part of the propulsion system. It is an important component of most fuel cell concepts and there seems to be a high potential to further improve the efficiency of conventional fuels. The development of pure electric cars is also explored. Here the study remarks that the commercialisation of such vehicles will strongly depend on the development of suitable batteries. In spite of decades of research and development activities, decisive technological breakthroughs regarding batteries are not in sight. 'Yet, a surprising breakthrough in battery technology is not completely impossible and would surely entail radical changes to both the transport and the energy sector,' say the authors of the study. No inventory on alternative fuel sources would be complete without an assessment of biofuels. While recognising the ease at which so-called first generation fuels, mainly biodiesel and bioethanol, can be produced today, the study sees second generation fuels as the way forward. Unlike their ancestors, second generation biofuels can be made using the whole plant or from biomass other than rapeseed and sugar cane. It is estimated that by 2030, roughly 20% to 30% of the EU's road transport fuels could be covered by biofuels derived from European biomass such as energy crops, agricultural and forestry residues or the organic fraction of municipal solid waste. But to meet the continent's fuel needs, it is likely that biomass will have to be imported from abroad. This should be critically discussed, argues the study, since importing biomass may be detrimental to ecologically sensitive areas worldwide. Last on the list of possible fuel alternatives is compressed natural gas technology (CNG). 'This is a feasible technology for the transport sector and has the potential to bring at least mid-term improvements in terms of energy security and GHG emissions,' notes the study. But its possible contribution to energy security strongly depends on the overall demand for natural gas. It is likely that CNG vehicles will become at least established for niche applications, such as in larger fleets or in inner cities. Meanwhile the study predicts that liquid petroleum gas (LPG) will offer environmental benefits at relatively low costs. However, since both CNG and LPG are based on fossil feedstock, they must be considered as bridging technologies. They might help to pave the way for 'cleaner' gaseous fuels such as hydrogen, bio-methane or dimethyl ethyl (DME), suggests the study.
For more information, please visit: http://www.europarl.europa.eu/stoa/publications/studies/stoa179_en.pdf