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Transport Mitigation Opportunities Global
Source: Climate Change 2001. Working Group III, Mitigation Section 3.4
In 1995, the transport sector produced 22% of global energy-related CO2 emissions. Every year this increases by 2.5% globally. Since 1990, growth has been mainly in the developing countries. It has been increasing by 7.3% per year in the Asia-Pacific region and actually decreasing by 5% per year in countries which are moving from a planned economy to a market economy, otherwise called EITs (Economies in Transition).
There are many new technologies aimed at reducing greenhouse gas emissions from the transportation sector.
Hybrid Electric Vehicles
Hybrid gasoline-electric cars have been introduced with fuel economies 50-100% better than current gas-powered cars of the same class.
A hybrid electric vehicle combines an internal combustion engine (or other fuelled power source) with an electric drivetrain and battery (or other electrical storage device, e.g., an ultracapacitor). This combination is much more energy efficient than current gas-powered cars.
Toyota introduced a sophisticated hybrid subcompact auto, the Prius. Honda also began selling in model year 2000 its Insight hybrid, a two-seater, and more recently a Civic hybrid for-door model. Ford, GM, Daimler/Chrysler and several others have hybrids in advanced development.
Hybrids have their greatest efficiency advantage (greater than 100%) over conventional vehicles in slow stop-and-go traffic. This gives them important applications as urban taxicabs, transit buses, and service vehicles such as garbage trucks. A study found that use of hybrid vehicles could reduce energy consumption (in litres/100 km) by medium-sized trucks in urban operations 23% to 63%.
Testing the Toyota Prius under a variety of driving conditions in Japan, gave 40% – 50% better fuel economy at average speeds above 40 km/h, 70% – 90% better in city driving at average speeds between 15 and 30 km/h and 100% – 140% better fuel economy under highly congested conditions with average speeds below 10 km/h. So congested city driving is where these vehicles excel in energy efficiency.
Fuel Cell Electric Vehicles (EVs)
The fuel economy of hydrogen fuel cell vehicles is projected to be 75% to 250% greater than that of conventional gasoline internal combustion engine (ICE) vehicles, depending on the drive cycle.
A fuel cell operates like a battery. A fuel cell converts chemical energy directly into electricity by combining oxygen from the air with hydrogen gas. However, unlike a battery, a fuel cell does not run down or require recharging. It will produce electricity as long as fuel, in the form of hydrogen, is supplied.
An individual fuel cell consists of two electrodes, one positively charged and one negatively charged, with a substance that conducts electricity (electrolyte) sandwiched between them. Oxygen from the air passes over one electrode and hydrogen over the other, generating electricity and water. The hydrogen fuel for a fuel cell EV can be supplied in several ways. Some vehicles carry a tank of pure hydrogen. Others could be equipped with a “fuel reformer” that converts hydrocarbon fuels÷ such as methanol, natural gas, or gasoline÷ into a hydrogen-rich gas. Individual fuel cells must be combined into groups called fuel cell stacks in order to achieve the necessary power required for motor vehicle applications.
Mid-size fuel cell passenger cars using hydrogen could achieve fuel consumption rates of 2.5 (gasoline equivalent) l/100 km in vehicles with lightweight, low drag bodies; while methanol or gasoline-powered fuel cell vehicles get between 3.2 and 4.0 l/100 km (gasoline equivalent), respectively. While gasoline is relatively more difficult to reform, it has the benefit of an existing refueling infrastructure, and progress has been made in reformer technology.
Biofuels are produced from wood, crops and waste. These sources contain sugar (glucose) and cellulose fibres. You may recall that cellulose is made of many molecules of glucose strung together in chains. Enzymes are used to break apart the cellulose into glucose. The glucose molecules are fermented by micro-organisms to produce ethanol (alcohol). Ethanol is blended with gasoline at concentrations of 5-15% and has been used commercially for over a decade. Other plants are rich in oils and are used to produce different types of Biofuels. These biofuels have the potential to play an increasingly important role as their production becomes more cost-effective.
Cities and nations around the world have begun to develop plans for achieving sustainable transport. A 1995 report by the ECMT (European Conference of Ministers of Transport) presents three policy “strands”. They form a progression leading to sustainability.
- The first strand represents “best practice” in urban transport policy. This combines land-use management strategies with advanced road traffic management strategies, environmental protection strategies, and pricing mechanisms. Land-use management strategies include zoning restrictions on low-density development and parking area controls. Environmental protection examples are tighter pollutant emissions regulations and fuel economy standards. Examples of pricing mechanisms are motor fuel taxes, parking charges, and road tolls. Even with these practices, transport-related CO2 emissions were projected to increase by about one-third in OECD (Organization for Economic Co-operation and Development) countries over the next 20 years and by twice that amount over the next 30 to 40 years.
- A second strand added significant investment in transit, pedestrian, and bicycle infrastructure to shape land use. It requires stricter controls on development, limits on road construction plus city-wide traffic calming, promotion of clean fuels and the setting of air quality goals for cities. In addition it demands congestion pricing for roads and user subsidies for transit. The addition of this strand was projected to reduce the growth in CO2 emissions from transport to a 20% increase over the next 20 years.
- The third strand added steep year-by-year increases in the price of fuel. This would ensure the use of high-efficiency, low-weight, low-polluting cars, vans, trucks, and buses in cities. Addition of the third strand was projected to reduce fuel use by 40% from 1995 to 2015.
ACTIVITY: How Much Does Your Vehicle Pollute?
1. Go to the Natural Resources Canada web page at the address below:
2. In the Table of Contents, read the topics, Understanding the Tables, and Car Classifications.
3. Choose Compare Vehicles from the list on the left side of the page. Enter the data for your family car, a hybrid vehicle, and another type.
a) What is the ranking for each of the vehicles?
b) What is the city driving fuel economy for the most efficient and the least efficient vehicle?
c) Look at the annual CO2 emissions column in the table. What is the difference between the most and least efficient vehicles? Include the units.
4. Now go to the US National Highway Traffic Safety Administration (NHTSA) web page at the address below:
5. Determine the safety rating for the vehicles you selected in number 3 above.
6. Based on the fuel economy, emissions ratings and safety ratings, which vehicle do you recommend purchasing? Explain your recommendation.