by Bob Cook
October 6, 2006
Transportation is the largest user of energy, accounting for more than 60% of all energy demand. More than 99% of all transportation is powered by petroleum fuels and more than 65% of U.S. petroleum consumption is from imported oil. Trends in petroleum and natural gas supply and demand indicate rising costs and prices will be the rule during the next twenty years.
In 2005, the Tucson region consumed more than 600 million gallons of gasoline and diesel fuels, up from 450 million gallons in 1998. Of greater concern, local expenditures for transportation fuels are increasing significantly, from $480 million in 1998 to $1.84 billion in 2005 – an increase of 380%.
Energy use as well as environmental impacts of transportation will become an even more important factor in the health of our economy. Deciding on competing energy strategies will require that rigorous energy and environmental analyses be applied across the board.
Given the size and diversity of the transportation sector, a number of strategic choices exist to reduce reliance on petroleum. These include electrification of transportation, alternate modes of mobility, conservation and fuel efficiency improvements, and development of biofuels. None of these strategies are sufficient to maintain current consumption trends but efforts in all these areas have already begun. For example, during the last decade the US Department of Energy’s Clean Cities program in the metro area has already achieved an annual displacement of 3 million gallons of petroleum fuels – a half of one percent of total consumption — in 2005 by using alternative fuels and hybrid electric vehicles.
There is increasing evidence that even the Kyoto Protocol goals will be insufficient to reverse and mitigate rising greenhouse gas levels. Other strategies for transportation will be necessary. These will likely require reversing the current trend of increasing per capita miles traveled by motorized means. These include lifestyle changes; compact, mixed-use land patterns; home-based work; and increase of local production over imports.
Our growing dependence on imported oil for transportation fuels is one of the most critical issues confronting transportation. While efforts to develop renewable biofuels from plant crops are important, most experts including the US Dept. of Energy agree that biofuels will yield less than a 20% of total fuel consumption in the long term. A recent University of Minnesota study published by the National Academy of Sciences showed that if every acre of corn were used for ethanol, it would replace only 12.3 percent of the US gasoline consumption. The national Renewable Fuel Standard mandates only 5% of total annual gasoline be displaced by ethanol in 2012.
Given that ethanol yields only 12% less greenhouse gas emissions compared with gasoline, it is clear that use of ethanol will not contribute to significant progress toward meeting the Kyoto Protocol goal of reversing CO2 emissions to 5% below 1990 levels. A 20% decrease in per capita gasoline consumption is far easier and cheaper to achieve using all the other strategies and would result in even less CO2 emissions.
Because of the inherent limitations of biofuels to substitute for fuel imports, this dependence on imported oil will continue to increase until we pursue other strategies including electrifying our transportation system.
Electric transportation provides another powerful argument for significant ramping up of renewable sources such as solar and wind electric generating capacity. This will facilitate the use of these new “portfolio” energy sources for transportation, not just for buildings, lighting, and water pumping. Use of solar and wind-generated electricity for transportation will also reduce the global greenhouse effects attributable to transportation fuels.
The metro region should increase investment in electric and plug-in hybrid-electric vehicles across the board including cars, trucks, conventional buses, trolley buses, express buses, and all forms of rail including streetcars, light rail and heavy rail.
The bottom-line for deciding on funding allocations for all energy strategies should be based on strong environmental and economic analyses. For example, corn-based ethanol is a limited choice because it requires vast quantities of land, water and other agro-inputs/outputs and returns only approximately 1.5 units of energy for every unit invested. On the other hand, wind–generated electricity averages 40 units of energy returned for every invested unit and solar-electric systems produce an average 30 units of energy for every invested unit.