Can Cars Save the Planet?
22 May, 2007 03:34 pm
No alternative fuel can single-handedly bring a solution to the environmental problems associated with modern-day mobility. With the threat of climate change looming on the horizon, the world has never been more desperate for a fuel that can save us from global warming and environmental devastation. Alternatives abound - but it turns out the 'perfect' green fuel does not exist.
A study carried out by Norwegian scientists Karl Georg Hoyer and Erling Holden of Oslo University College and Western Norway Research Institute, concludes that none of the so-called 'alternative' fuels possess the qualities that could potentially bring for a final solution to today's transport-related environmental problems. The two researchers have drawn up a league table for alternative fuels, ranking 16 of them according to three environmental performance indicators: energy use, greenhouse gas emissions (CO2) and emissions of local or regional pollutants (NOx). Each energy form was given a weight from 1 to 16, depending on its impact in the three areas. The adding of the weights provided a score for each energy chain, allowing for direct comparison.
Hoyer and Holden, who share a background within civil engineering and social sciences, have chosen a life-cycle approach to each fuel, or 'energy chain', which includes the performance of a fuel all the way from the cradle to the grave ? or from well to wheel. Thus, it becomes apparent that a fuel which might at first glance seem capable of bringing about a green revolution due to low emissions, may in fact be as harmful to the environment as other fuels because producing it requires so much energy. In other words, a hydrogen car may be a winner if you limit your assessment to emissions, but producing the hydrogen is a process which more often relies on energy from gas than from renewable forms of energy, such as hydro power.
Which Fuel Wins?
The outcome of Hoyer and Holden's analysis is, in a way, a blurring of what may previously have seemed simple: Alternative fuels are not automatically 'environmentally friendly' just because they score highly on one of the three environmental indicators. In this study, the best score is achieved by fuel cell-powered vehicles using hydrogen gas obtained from natural gas methane. Petrol vehicles are at the bottom of the table, with hybrid vehicles that can run on compressed natural gas or petrol doing only a little bit better. In all, the study thus shows that although the fuels we rely on at present are not doing the environment much good, alternative fuels are not in themselves the answer to our problems. "It must be emphasised that no single chain comes out with the best score on all impact categories," the researchers say, "There are always some sorts of trade-offs involved. Thus, there are no obvious winners; only good or bad trade-offs between different impact categories."
The Future Road
Even as the world moves rapidly towards depletion of the sources of fossil fuels, there is no consensus on the best way ahead to more environmentally sustainable forms of mobility. Three main routes each enjoy support from lobbying groups: transporting goods and people more efficiently, travelling differently, and transporting less than today. Hoyer and Holden's stance is that the future road is simply not paved with alternative fuels: "It is only a combination of the three that can really be paved with alternative fuels: the efficiency route to develop energy efficient vehicles for alternative energy sources; the substitution route to expand the use of public transport, walking and bicycling; and the reduction route to limit the total levels of mobility".
K. G. Hoyer et al. "Alternative fuels and sustainable mobility: is the future road paved by biofuels, electricity or hydrogen". International Journal of Alternative Propulsion , Vol. 1, No. 4 2007