Because transportation is such a large contributor to global warming, both globally and in the United States, climate and energy experts say finding clean alternatives to gasoline is also key to replacing fossil fuels and slowing global warming. Just as there is debate and competing research about which type of alternative transportation fuel should be developed to produce electricity, however, there is also competition among possible new transportation fuels. So far, in the United States, significant funding has been put into two transportation technologies—ethanol and hydrogen fuel cells. Many energy commentators say cars powered by electric batteries are the technology closest to mass production capability, however. (more…)

Energy quality is the relative economic usefulness per heat equivalent unit of different fuels and electricity. One way of measuring energy quality is the marginal product of the fuel, which is the marginal increase in the quantity of a good or service produced by the use of one additional heat unit of fuel. These services also include services received directly from energy by consumers. Some fuels can be used for a larger number of activities and/or for more valuable activities. For example, coal cannot be used directly to power a computer whereas electricity can. The marginal product of a fuel is determined in part by a complex set of attributes unique to each fuel: physical scarcity, capacity to do useful work, energy density, cleanliness, amenability to storage, safety, flexibility of use, cost of conversion, and so on. But also the marginal product is not uniquely fixed by these attributes. (more…)

The European Automobile Manufacturers Association (ACEA) has offered, and the European Commission (EC) has accepted, a voluntary commitment to reduce the CO2 emissions from new light-duty passenger vehicles, with firm fleetwide targets of 140 g CO2 /km (B41 mpg for gasoline) by 2008, measured under the new European test cycle (Directives 93/116/EC and 99/100/EC). This represents approximately a 25% reduction from the 1995 average of 187 g/km (B30 mpg) on this cycle. The European cycle is likely to produce lower fuel economy ratings than the U.S. combined urban/ highway cycle, so the ‘‘U.S. equivalent’’ miles per gallon ratings of the year 2008 European fleet will likely be higher than 41 mpg if the targets are met. (more…)

Renewable energy sources cannot run out and causes so little damage to the environment that its use does not need to be restricted. No energy system based on mineral resources is renewable because, one day, the mineral deposits will be used up. This is true for fossil fuels and uranium. The debate about when a particular mineral resource will run out is irrelevant in this context. Renewable energy sources are replenished continuously.

Renewable energy sources—solar, wind, biomass (under specific conditions), and tides—are based directly or indirectly on solar energy. Hydroelectric power is not necessarily a renewable energy source because large-scale projects can cause ecological damage and irreversible consequences. Geothermal energy heat is renewable but must be used cautiously to guard against irreversible ecological effects. (more…)