We must include in our accounting what it takes to produce and distribute the fuel, to drive the vehicle through its lifetime of 150,000 miles (240,000 kilometers) and to manufacture, maintain and dispose of the vehicle. These three phases of vehicle operation are often called well-to-tank (this phase accounts for about 15 percent of the total lifetime energy use and greenhouse gas emissions), tank-to-wheels (75 percent), and cradle-to-grave (10 percent). Surprisingly, the energy required to produce the fuel and the vehicle is not negligible. This total life-cycle accounting becomes especially important as we consider fuels that do not come from petroleum and new types of vehicle technologies. It is what gets used and emitted in this total sense that matters.
Improving existing light-duty vehicle technology can do a lot. By investing more money in increasing the efficiency of the engine and transmission, decreasing weight, improving tires and reducing drag, we can bring down fuel consumption by about one third over the next 20 or so years—an annual 1 to 2 percent improvement, on average. (This reduction would cost between $500 and $1,000 per vehicle; at likely future fuel prices, this amount would not increase the lifetime cost of ownership.) These types of improvements have occurred steadily over the past 25 years, but we have bought larger, heavier, faster cars and light trucks and thus have effectively traded the benefits we could have realized for these other attributes. Though most obvious in the U.S., this shift to larger, more powerful vehicles has occurred elsewhere as well. We need to find ways to motivate buyers to use the potential for reducing fuel consumption and greenhouse gas emissions to actually save fuel and contain emissions.
In the near term, if vehicle weight and size can be reduced and if both buyers and manufacturers can step off the ever increasing horsepower/performance path, then in the developed world we may be able to slow the rate of petroleum demand, level it off in 15 to 20 years at about 20 percent above current demand, and start on a slow downward path. This projection may not seem nearly aggressive enough. It is, however, both challenging to achieve and very different from our current trajectory of steady growth in petroleum consumption at about 2 percent a year.
In the longer term, we have additional options. We could develop alternative fuels that would displace at least some petroleum. We could turn to new propulsion systems that use hydrogen or electricity. And we could go much further in designing and encouraging acceptance of smaller, lighter vehicles.
The alternative fuels option may be difficult to implement unless the alternatives are compatible with the existing distribution system. Also, our current fuels are liquids with a high-energy density: lower-density fuels will require larger fuel tanks or provide less range than today’s roughly 400 miles. From this perspective, one alternative that stands out is nonconventional petroleum (oil or tar sands, heavy oil, oil shale, coal). Processing these sources to yield “oil,” however, requires large amounts of other forms of energy, such as natural gas and electricity. Thus, the processes used emit substantial amounts of greenhouse gases and have other environmental impacts. Further, such processing calls for big capital investments. Nevertheless, despite the broader environmental consequences, nonconventional petroleum sources are already starting to be exploited; they are expected to provide some 10 percent of transportation fuels within the next 20 years.
Biomass-based fuels such as ethanol and biodiesel, which are often considered to emit less carbon dioxide per unit of energy, are also already being produced. In Brazil ethanol made from sugarcane constitutes some 40 percent of transport fuel. In the U.S. roughly 20 percent of the corn crop is being converted to ethanol. Much of this is blended with gasoline at the 10 percent level in so-called reformulated (cleaner-burning) gasolines. The recent U.S. national energy policy act plans to double ethanol production from the current 2 percent of transportation fuel by 2012. But the fertilizer, water, and natural gas and electricity currently expended in ethanol production from corn will need to be substantially decreased. Production of ethanol from cellulosic biomass (residues and wastes from plants not generally used as a food source) promises to be more efficient and to lower greenhouse gas emissions. It is not yet a commercially viable process, although it may well become so. Biodiesel can be made from various crops (rapeseed, sunflower, soybean oils) and waste animal fats. The small amounts now being made are blended with standard diesel fuel.
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Add CommentCombustion engines may be adapted to use hydrogen and/or gasoline using a double injection system. Operation can change from hydrogen to gasoline when no hydrogen pump is on the road. BMW, GM and others have such cars. China and India, desperate in need to reduce dependence on oil, are highly interested on the global Hydrogen initiative, using solar energy according to Kosuke Kurokawa and the global grid according to Fuller.
Reply | Report Abuse | Link to thisKarl Heinz Wilm
www.desertenergyproject.net/Global_Initiative.pdf
"First, it is well suited to its primary context, the developed world. Over decades, it has had time to evolve so that it balances economic costs with users needs and wants. Second, this vast optimized system relies completely on one convenient source of energypetroleum"
Reply | Report Abuse | Link to thisIf you start with false assumptions about the "optimization" of current transport systems, the problem can never be solved. Our current system of provision of vast areas of subsidised car parking, and roads are not based on empirical research. Users needs and costs cannot be addressed when they have no choice or knowledge of how their money is spent. Vast sums of money are wasted building infrastructure which is worse than useless, it is not efficient in terms of time, economics, space and land use not to mention the negative health effects of a life spent sitting on a car seat.