According to Randolph and Masters (2008), transportation has a great dependency on oil, over two-thirds of the petroleum products utilized in the US and more than half of the world oil is used on transportation. Whilst they also argue that the pollution caused by transportation has been significant and profound. Such dependency can be dangerous because the earth is encountering the energy crisis; inflation and upheavals may also easily caused by the oil shocks (Seitz, 2008). Therefore, transition from fossil fuels to alternative energy is needed in the contemporary society. There are three main alternatives to fossil fuels for public and personal transportation: biofuels, electricity and hydrogen. Apart from measures mentioned above to replace fossil fuels, there are also some efficiency measures to reduce fossil fuels. However, the efficiency measures are not really alternatives, so this essay will probably consider those replacement measures and evaluate them separately in the criteria of timescale, cost and practicality and then will recommend the best and viable one from the three alternatives.
Fossil fuels for public and personal transportation have recently been a cause of concern among people nearly all around the world. There are mainly two reasons for this concern. One is about the energy crisis. Although people are not running out of energy, they are running out of energy resources, especially for nonrenewable ones. Specifically, the developed countries are confronted with the energy crisis because the era of cheap energy is end. For example, oil is being utilized 1000 barrels a second in 2005 and the retail price per gallon of regular gas in the US has rose from 0.27 dollars to 2.07 dollars in almost 50 years (Seitz, 2008). The other reason is the impacts on environment. Middleton (2008) maintains that transport has been a major source of air pollution because of its heavy dependence upon the burning of fossil fuels. Pollutants caused by the combustion have a number of environmental impacts. For instance, carbon dioxide contributes to the climate change, and nitrogen and sulphur oxides are the main causes of acid rain (Middleton, 2008).
Biofuels have a great potential to replace the petroleum in the future; consequently, they may be considered as an alternative to fossil fuels. Generally biofuels can be defined as any form of fuel made from biomass, but for transportation, liquid fuels are particularly expected because they are easier to blend with current fuels and they are more compatible with vehicles (IEA, 2004). Koshel and Mcallister (2008) maintains that biofuels, especially for corn based ethanol is improbable to be a practical long term solution to alleviate the dependency on oil but a short term transitional fuel. Similarly, the Worldwatch Institution (2007) also recognize this, pointing out that biofuels are a short term solution and they can meet a greater part of entire transport energy requirements if they can become more efficient. At present, human has already benefited from biofuels since this alternative help to meet many of the challenges come to people. For example, it is widely agreed biofuels can help to reduce the emission of greenhouse gas and the reliance on oil (Worldwatch Institution, 2007).
However, it has been pointed out that there should be a comparison between the benefits and the costs (IEA, 2004). The International Energy Agency (2004) claims that the estimation of the value of such benefits is difficult but there is an inclination to focus on the costs. A case of this can be seen in OECD nations: after considering the current feedstock and alteration technology, the cost for using conservative biofuels appears to be high. Koshel and Mcallister (2008) take a different view, proposing that approaches to assess the benefits and costs are not the same, they have different judge criteria. It is an uncertain aspect of biofuels assessment. The fact that biofuels have large compatibility with vehicle and other fuels, leads to the inference that biofuels are feasible solutions. Middleton (2008) agrees that biofuels are practical, but adds that due to the increase use of biofuels, large areas are needed for cultivation. If farmers are likely to be more lucrative, they may grow crops for biofuels rather than food production. Therefore, things still need to be done in this area, if the drawbacks can be avoided, biofuels may probably replace fossil fuels in decades.
Electrification of most transport is a good plan to replace fossil fuels; as a result electricity can be the second alternative to fossil fuels. According to Lodal and Sandalow (2009), a "plug-in electric vehicle" (PEV) is a kind of car or truck that can be recharged. These vehicles can be divided into two types: "all-electric" (running on electricity only) and "plug-in hybrids" (running on both electricity and liquid fuels). They also argue that plug-in hybrid cars would like to become the first choice for light vehicles among people between 2030s and 2050s. Sperling (1994) refutes this view, believes that it only needs a short time to reach that goal. But Sperling (1994), Lodal and Sandalow (2009) all agree that plug-in electric cars will cost much to replace fossil fuels but little to recharge the cars. The main expenditure is the manufacture of batteries and the driving cost will fall dramatically. For instance, plug-in electric vehicles will cost the equivalent of roughly 75 cents per gallon to drive if they are at the national average electricity prices (Lodal and Sandalow, 2009).
Because of the high replacement costs, it perhaps still has at least ten year for plug-in electric vehicles to achieve general acceptance. Once the challenge of battery has been overcome, supply chains will need to be established with facilities for mass production (Lodal and Sandalow, 2009). Although battery has been a technological barrier when considering the practicality of plug-in electric vehicle, this alternative still has great potential to replace fossil fuels. Electricity used in transportation accounted to less than 0.1% of alternative fuel in 2005, but it has grown significantly since the year of 1995 (Middleton, 2008). And as the same with biofuels, electricity also helps to reduce pollution, so it provides a clean and safe alternative to conventional (internal combustion) engines. Overall, although technological barrier remains, progress has been made in the past years. Electricity also have a great potential to replace fossil fuels.
Apart from biofuels and electricity, hydrogen seems to be a low-carbon alternative to fossil fuels. Hydrogen is widely regarded as a perfect clean fuel whether to burn directly or transfer into electricity in fuel cells, such kind of fuel cell technology in transportation provides an opportunity to address petroleum and pollution (Randolph and Masters, 2008). It is generally agreed that hydrogen as a transportation fuel is a long-term alternative. Hydrogen is just an energy carrier, is not the source of energy, so energy source is needed to produce hydrogen (MacKay, 2009). Randolph and Masters (2008) agree that there is still a long way from perfecting the process of producing hydrogen, great efforts are needed to find the right materials to produce hydrogen, and to collect the separated hydrogen. But the benefits brought by hydrogen-powered vehicles have the potential to grow continuously due to the technological development and marketing infiltration (Committee on Assessment of Resource Needs for Fuel Cell and Hydrogen Technologies, 2008).
A transition to hydrogen-powered vehicles will have extensive costs; constant expenditures are spent on transition from fossil fuels to hydrogen, primarily in support of technology research and development, and later to support the early construction of the hydrogen infrastructure and the introduction of hydrogen-powered vehicles into the market (Committee on Assessment of Resource Needs for Fuel Cell and Hydrogen Technologies, 2008). The hydrogen-powered vehicles actually are not completely clean; vehicles using grid-average power for electrolysis also had the highest CO2 emissions, 42% greater than the conventional gasoline car (Randolph and Masters, 2008). In general, since hydrogen pose significant barriers during the transition, biofuels, plug-in electric vehicles may offer an easier and more cost-effective option.
In conclusion, transportation is an important energy part because of its increasing demand, its dependency on oil, and its contribution to air pollution. If we are to adequately address our oil and carbon problems, transportation is the first place to start. We need to improve vehicle efficiency and increase use of alternative fuels to replace petroleum fuels (Randolph and Masters, 2008). And after considering all the three alternatives, electricity can be the best alternative since they have already been used worldwide, but improvements should be made in this area to overcome the barrier caused by battery. At the same time, government should make public transportation attractive, affordable and efficient and scientists should make enough improvements in technology. Although there are energy crisis and environmental damage nowadays, things may be in a better condition because the awakening of people's mind and human beings will adopt more efficient measures in the future.