Introduction

The steady rise in atmospheric CO2 levels (Figure 1) has been identified as the major cause of global average temperature rise, which has occurred since the start of the industrial revolution early in the nineteenth century and has accelerated in the last 50 years. The world population growth in the last 50 years has been from about 2.6 to 6.2 billion, mostly in the less developed countries (Figure 2). All these people naturally aspire to a more prosperous lifestyle and this inevitably leads to more pollution and more rapid consumption of fossil fuels and emission of greenhouse gases, principally CO2.

Fig. 1. CO2 concentration in the atmosphere: Mauna Loa Curve

E.J. Moniz (ed.), Climate Change and Energy Pathways for the Mediterranean, 145-161. © 2008 Springer.

Fig. 2. Global population growth

The US currently emits about 25% of the world total of CO2. About one third of these emissions are from the transportation sector (Figure 3), and this proportion is approximately the same as emissions from electrical utilities. Growth in the numbers of vehicles in developed countries has been phenomenal in the last 50 years (Figure 4) and this trend is likely to be repeated in the developing countries with even more rapid growth rates. In order for mankind to continue to enjoy the standards of living we currently experience and satisfy all people's aspirations for the future, we must solve the problem of greenhouse gas emissions to the atmosphere. Much research and development is being undertaken on CO2-free electric power generation using renewables, nuclear power and fossil fuel derived power with CO2 capture and storage. The electric power section, with its very large point source CO2 emissions, is amenable to CO2 capture technology. The challenge we have is to implement a CO2 capture method that can be applied to the huge number of vehicles, each of which generates CO2 emissions from the combustion of hydrocarbon fuel. The only possibility is either electric drive with storage batteries, which can be recharged from the electrical supply system or to use a fuel that is not going to produce any significant net greenhouse gas emissions.

Fig. 3. US carbon Fig. 4. Growth of vehicle numbers in the UK

emissions (25% of world total)

Fig. 3. US carbon Fig. 4. Growth of vehicle numbers in the UK

emissions (25% of world total)

The fuel of choice must be hydrogen, which produces only water when combusted with air. The type of engine used will be either an internal combustion engine, which will need to be designed to limit NOX emissions, or a fuel cell generating electricity, which is then used in the electric motor drive system.

Primary fossil fuels will be used to generate the bulk of the hydrogen, which should be regarded as an energy carrier. Some hydrogen could be available from renewable and nuclear energy sources via electrolysis, particularly in off-peak periods, but for the next 50 years or so, fossil fuels will be the main source of hydrogen for the transportation sector. When using fossil fuels it will be necessary to capture CO2 during the hydrogen manufacturing process and dispose of the CO2 by, for example, storage in geological formations. This will result in a largely CO2-emissions free fuel base for the ground transportation sector.

Guide to Alternative Fuels

Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

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