Transportation is one of the largest economic sectors in the world, growing at a rate of 2.5% a year. In addition to emitting 25% of the earth’s total greenhouse gas emissions, the transportation industry is responsible for air and water pollution. The sector also consumes vast amounts of energy and natural resources for road, rail, and runway maintenance; vehicle construction; and fuel extraction and refinement
Airplanes currently produce 3% of the earth’s total greenhouse gas emissions, which are three times the amount produce by automobiles. In addition to carbon dioxide and nitrogen oxide, airplanes emit water vapor that form condensation trails, or contrails in the upper atmosphere. These contrails increase earth’s heat retention by. Airplane contrails also increase particulate matter, adding to ozone creation. In both passenger and freight transport, the aviation sector is expected to grow by 5% a year, while the current commercial airplane fleet is projected to double by 2025.
Trends in the Industry
On the Horizon - Alternative Fuels
For more information on alternative fuels, visit Global Challenges – Energy.
Trucks and automobiles pollute the air with the following:
In the US, transportation accounts for 33% of greenhouse gas emissions, and will grow at an estimated 1.8% a year. Of that amount 60% comes from personal vehicles, while the remaining 40% comes from aviation, rail, ocean travel and commercial goods trucking. Though trucking emits less greenhouse gases, overall, it is more damaging to the climate, according to the UN. While the automobile and public transit industry have reduced impact and use of cars, little has changed for commercial trucking.
Changes in the Automobile Industry
Batteries are the largest factor in energy efficiency, speed, and distance. The life span of most batteries is an estimated 100,000 miles. Less need for maintenance on fewer parts makes up for high battery replacement costs (estimated at $3,000). Most EVs use one of the following batteries:
EV’s are more energy efficient than hybrids or standard, internal combustion automobiles. The amount of carbon EVs use, or their carbon footprint, is measured from their power source and emissions. Though EV operation releases no emissions, it takes energy to charge the engine. EVs have 55% to 99% fewer emissions than conventional cars, depending on the EV’s power source. An EV charged from a power grid (wall outlet) has a carbon footprint that is directly tied to the utility's power source, be it renewable, natural gas fired generation or coal.
EVs are recommended for short distance travel. However, manufacturers plan to release more affordable, long-distance EV models in the next few years.
Cost. Hybrids are between $3-6,000 more expensive than conventional cars. Improved gas mileage and government tax incentives are ways to offset and eventually recoup initial cost. Here's where you can find out about federal tax credits for hybrids bought in the U.S.
Fuel efficiency. According to the U.S. EPA, the average U.S. fuel efficiency is 23 mpg. For hybrids, fuel efficiency can reach 55 mpg. Due to the dominance of the electric motor, hybrids get better gas mileage in the city rather than the highway.
Batteries. Hybrid cars use nickel metal hydride batteries which are less toxic than conventional nickel cadmium or lead acid batteries that are commonly found in conventional cars and electronics. They are fully recyclable and Toyota pays a bounty of $200 for each used battery. They are expected to last the lifetime of the car, and are under warranty for up to 10 years or 100,000 miles.
Retrofitting for Alternative Fuels
- Vegetable Oil. To use vegetable oil as a fuel, one must heat it before using to in a standard diesel engine. The most common method is to install a heat exchanger, an additional diesel tank, and a three-way valve. With this method, diesel starts the car as the exchanger heats the vegetable oil, and once warmed, the engine switches over. Conversion kits cost about $1200.
For more about the availability of biofuels, visit Green Daily Travel.
- Biodiesel. Made from vegetable oil by removing the glycerin (thickening agent), biodiesel is combined with petrodiesel, and can be used by any diesel engine without modification.
- Ethanol. Ethanol is the biofuel alternative to gasoline, derived from certain plants. Typically, ethanol is combined with gasoline to maximize performance. Any blend higher than 10% ethanol requires engine modifications. Referred to as fuel-flex vehicles, (these cars) are becoming increasingly available. To make a car capable of running on ethanol, its engine system must have an alcohol senor to adjust the fuel injection to create the proper air-to-fuel ratio.
- Compressed Natural Gas. Lower in greenhouse gas emissions, compressed natural gas (CNG) is an alternative to gasoline. For adaptation CNG cars need fuel-metering devices. A standard internal combustion engine needs a pressure regulator to convert it from storage pressure to metering pressure, and a gas mixer or injector. Since CNG is a volatile gas, it takes up more space than liquid gasoline. Recent advances in composite materials include lighter alternatives for large tanks, which improve fuel efficiency. Though still few, home fueling systems and utility sponsored refueling stations are becoming more available.
On the Horizon
In addition, researchers are considering liquid hydrogen as an alternative fuel. Along with zero emissions, hydrogen has one of the greatest energy per unit of weight ratios of all available alternative fuels. The downside is that liquid hydrogen production requires much energy. Until sources of alternative, low-emission energy increase, hydrogen powered vehicles will have a large carbon footprint.
Because they can distribute more pounds per axle with little friction (using less fuel per ton of goods), rail systems emit significantly fewer greenhouse gasses than aviation and road transport. In the US, passenger and freight trains account for roughly 3% of the country’s total greenhouse gas emissions. The two current primary fuel sources for rail are:
Changes in the Industry
- Biodiesel. Many rail systems are adding biodiesel to their fuel load. Britain’s high speed train, Thames Voyager, began running on 20% biodiesel in late 2007. Designers expect the new fuel to reduce the train’s overall emissions by 14%.
- Hybrid Locomotion. While trains use a combination of diesel and electric mechanisms for propulsion, new developments have lead to greater fuel efficiency and reduced emissions. Electro-diesel trains use either a diesel or electric motor tending to serve small and local markets. By contrast, a diesel-electric system operates much like full hybrid cars by using both engines for propulsion; utilizing regenerative breaking which stores the kinetic energy from breaking to apply later; and shuts off the diesel motor at slower, stop and go speeds. It is expected to reduce emissions by up to 90% and fuel usage by up to 60%.
Options for Train Travel
- Commuter trains that connect residential areas with commercial centers. These trains travel anywhere from 15 to 100 miles at speeds between 55 to 100 miles per hour. They have relatively frequent stops, are generally comfortable, and offer limited luggage space.
- High Speed Rail. Traveling over longer distances at higher speeds than commuter trains, these rail systems connect large cities. Planners designed high-speed rail with limited stops to compete with air and automobile transport.
- Long Distance Trains. Usually diesel powered and running at lower speeds, long distance trains connect far away regions, often crossing international borders. As aviation and car travel became more popular, long distance train travel declined. Long distance trains are now largely used for touring and often include sleeping and dining cars.
On the Horizon
- Hydrogen Fuel Cell Locomotion. The East Japanese Railway Company is working on the first hydrogen fuel cell, hybrid train. It produces zero greenhouse gas emissions. Engineers are still working to increase the train’s speed and travel range.
- Superconducting High Speed Trains. These trains are known as the “train of the future”. By a process referred to as electromagnetic induction, these trains are propelled by the repulsive force between the magnetic fields of the rail and the train, causing the train to rise above the tracks at speeds up to 350 miles per hour. Operating and energy costs are lower than high-speed trains, but maglevs (magnetically levitating trains) are incompatible with existing rail lines and require a whole new infrastructure. Only a few operate in Japan and China.
When aviation took over long distance travel, freight transport dominated ocean transportation. Recently, the UN reported that shipping emits 4.5% of the world’s carbon. The UN projects it will grow 30% by 2020.
Problems with Bunker Fuel
Changes in the Industry
- Adapting ships to use compressed natural gas and biodiesel fuel.
Options for Passengers
Cruise Ships. Modern day cruise ships are equivalent to ocean liners from the days before air travel. Emphasizing luxury and pleasure touring, cruises have little to do with getting from one place to another. The transatlantic Queen Elizabeth 2 and Queen Mary 2 closely resemble old ocean liners in speed and functionality, but operate largely as cruise ships. For more on environmental impact of cruise ships, visit Green Leisure Travel.