The Toyota Prius is the world's top selling hybrid electric vehicle, with global sales of 3.7 million units through April 2016.[1] Some owners use its identity to make an environmental statement.[2]
An environmental analysis extends beyond just the operating efficiency and emissions. A life-cycle assessment involves production and post-use considerations. A cradle-to-cradle design is more important than a focus on a single factor such as energy efficiency.[9][10]
Cars with similar production of energy costs can obtain, during the life of the car (operational phase), large reductions in energy costs through several measures:
Green vehicles include vehicles types that function fully or partly on alternative energy sources other than fossil fuel or less carbon-intensive than gasoline or diesel.
Another option is the use of alternative fuel composition in conventional fossil fuel-based vehicles, making them function partially on renewable energy sources. Other approaches include personal rapid transit, a public transportation concept that offers automated, on-demand, non-stop transportation on a network of specially built guideways.
Electric cars are typically more efficient than fuel cell-powered vehicles on a Tank-to-wheel basis.[15] They have better fuel economy than conventional internal combustion engine vehicles but are hampered by range or maximum distance attainable before discharging the battery. The electric car batteries are their main cost. They provide a 0%[16] to 99.9% reduction in CO2 emissions compared to an ICE (gasoline, diesel) vehicle, depending on the source of electricity.[17]
Hybrid cars may be partly fossil fuel (or biofuel) powered and partly electric or hydrogen-powered. Most combine an internal combustion engine with an electric engine, though other variations too exist. The internal combustion engine is often either a gasoline or Diesel engine (in rare cases a Stirling engine may even be used[18]). They are more expensive to purchase but cost redemption is achieved in a period of about 5 years due to better fuel economy.[13][14]
Compressed air cars, stirling vehicles, and others
Solar car races are held on a regular basis in order to promote green vehicles and other "green technology". These sleek driver-only vehicles can travel long distances at highway speeds using only the electricity generated instantaneously from the sun.
A conventional vehicle can become a greener vehicle by mixing in renewable fuels or using less carbon intensive fossil fuel. Typical gasoline-powered cars can tolerate up to 10% ethanol. Brazil manufactured cars that run on neat ethanol, though there were discontinued. Another available option is a flexible-fuel vehicle which allows any blend of gasoline and ethanol, up to 85% in North America and Europe, and up to 100% in Brazil.[19] Another existing option is to convert a conventional gasoline-powered to allow the alternative use of CNG. Pakistan, Argentina, Brazil, Iran, India, Italy, and China have the largest fleets of natural gas vehicles in the world.[20]
Diesel-powered vehicles can often transition completely to biodiesel, though the fuel is a very strong solvent, which can occasionally damage rubber seals in vehicles built before 1994. More commonly, however, biodiesel causes problems simply because it removes all of the built-up residue in an engine, clogging filters, unless care is taken when switching from dirty fossil-fuel derived diesel to bio-diesel. It is very effective at 'de-coking' the diesel engines combustion chambers and keeping them clean. Biodiesel is the lowest emission fuel available for diesel engines. Diesel engines are the most efficient car internal combustion engines. Biodiesel is the only fuel allowed in some North American national parks because spillages will completely bio-degrade within 21 days. Biodiesel and vegetable oil fuelled, diesel engined vehicles have been declared amongst the greenest in the US Tour de Sol competition.
This presents problems, as biofuels can use food resources in order to provide mechanical energy for vehicles. Many experts point to this as a reason for growing food prices, particularly US Bio-ethanol fuel production which has affected maize prices. In order to have a low environmental impact, biofuels should be made only from waste products, or from new sources like algae.
Public transportation vehicles are not usually included in the green vehicle category, but Personal rapid transit (PRT) vehicles probably should be. All vehicles that are powered from the track have the advantage of potentially being able to use any source of electric energy, including sustainable ones, rather than requiring liquid fuels. They can also switch regenerative braking energy between vehicles and the electric grid rather than requiring energy storage on the vehicles. Also, they can potentially use the entire track area for solar collectors, not just the vehicle surface. The potential PRT energy efficiency is much higher than that which traditional automobiles can attain.
Solar vehicles are electric vehicles powered by solar energy obtained from solar panels on the surface (generally, the roof) of the vehicle. Photovoltaic (PV) cells convert the Sun's energy directly into electrical energy. Solar vehicles are not practical day-to-day transportation devices at present, but are primarily demonstration vehicles and engineering exercises, often sponsored by government agencies. However, some cities have begun offering solar-powered buses, including the Tindo in Adelaide, Australia.
Wind-powered electric vehicles primarily use wind-turbines installed at a strategic point of the vehicle, which are then converted into electric energy which causes the vehicle to propel.
Animal powered vehicles
Horse and carriage are just one type of animal propelled vehicle. Once a common form of transportation, they became far less common as cities grew and automobiles took their place. In dense cities, the waste produced by large numbers of transportation animals was a significant health problem. Oftentimes the food is produced for them using diesel powered tractors, and thus there is some environmental impact as a result of their use.
Human-powered transport includes walking, bicycles, velomobiles, row boats, and other environmentally friendly ways of getting around. In addition to the health benefits of the exercise provided, they are far more environmentally friendly than most other options. The only downside is the speed limitations, and how far one can travel before getting exhausted.
Benefits of green vehicle use
Environmental
Vehicle emissions contribute to the increasing concentration of gases linked to climate change.[26] In order of significance, the principal greenhouse gases associated with road transport are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O).[27] Road transport is the third largest source of greenhouse gases emitted in the UK, and accounts for about 27% of total emissions,[28] and 33% in the United States.[29] Of the total greenhouse gas emissions from transport, over 85% are due to CO2 emissions from road vehicles. The transport sector is the fastest growing source of greenhouse gases.[30]
Health
Vehicle pollutants have been linked to human ill health including the incidence of respiratory and cardiopulmonary disease and lung cancer. A 1998 report estimated that up to 24,000 people die prematurely each year in the UK as a direct result of air pollution.[31] According to the World Health Organization, up to 13,000 deaths per year among children (aged 0–4 years) across Europe are directly attributable to outdoor pollution. The organization estimates that if pollution levels were returned to within EU limits, more than 5,000 of these lives could be saved each year.
A study by CNW Marketing Research suggested that the extra energy cost of manufacture, shipping, disposal, and the short lives of some of these types of vehicle (particularly gas-electric hybrid vehicles) outweighs any energy savings made by their using less petroleum during their useful lifespan.[33] This type of argument is the long smokestack argument.[34] Critics of the report note that the study prorated all of Toyota's hybrid research-and-development costs across the relatively small number of Priuses on the road, rather than using the incremental cost of building a vehicle; used109,000 miles (175,000 km) for the length of life of a Prius (Toyota offers a 150,000-mile (240,000 km) warranty on the Prius' hybrid components, including the battery), and calculated that a majority of a car's cradle-to-grave energy gets expended during the vehicle's production, not while it is driven.[35]Norwegian Consumer Ombudsman official Bente Øverli stated that "Cars cannot do anything good for the environment except less damage than others." Based on this opinion, Norwegian law severely restricts the use of "greenwashing" to market automobiles, strongly prohibiting advertising a vehicle as being environmentally friendly, with large fines issued to violators.[36][37][38][39]
Some studies try to compare environmental impact of electric and petrol vehicles over complete life cycle, including production, operation, and dismantling.
[40][41][42][43]
In general, results differ vastly dependent on the region considered, due to difference in energy sources to produce electricity that fuels electric vehicles. When considering only CO2 emissions, it is noted that production of electric cars generate about twice as much emissions as that of internal combustion cars.[40] However, emissions of CO2 during operation are much larger (on average) than during production. For electric cars, emissions caused during operation depend on energy sources used to produce electricity and thus vary a lot geographically. Studies suggest that when taking into account both production and operation, electric cars would cause more emissions in economies where production of electricity is not clean, e.g., it is mostly coal based.[41][42] For this reason, some studies found that driving electric cars is less environmentally damaging in western US states than in eastern ones, where less electricity is produced using cleaner sources. Similarly, in countries like India, Australia or China, where large portion of electricity is produced by using coal, driving electric vehicles would cause larger environmental damage than driving petrol vehicles. When justifying use of electric cars over petrol cars, these kinds of studies do not provide sufficiently clear results. Environmental impact is calculated based on fuel mix used to produce electricity that powers electric cars. However, when a gas vehicle is replaced by an equivalent electric vehicle, additional power must be installed in electrical grid. This additional capacity would normally not be based on the same ratios of energy sources ("clean" versus fossil fuels) than the current capacity. Only when additional electricity production capacity installed to switch from petrol to electric vehicles would predominantly consist of clean sources, switch to electric vehicles could reduce environmental damage. Another common problem in methodology used in comparative studies is that it only focuses on specific kinds of environmental impact. While some studies focus only on emission of gas pollutants over life cycle or only on greenhouse gas emissions such as CO2, comparison should also account for other environmental impacts such as pollutants released otherwise during production and operation or ingredients that can not be effectively recycled.[44] Examples include use of lighter high performing metals, lithium batteries and more rare metals in electric cars, which all have high environmental impact.
A study that also looked at factors other than energy consumption and carbon emissions has suggested that there is no such thing as an environmentally friendly car.[45]
The use of vehicles with increased fuel efficiency is usually considered positive in the short term but criticism of any hydrocarbon-based personal transport remains. The Jevons paradox suggests that energy efficiency programs are often counter-productive, even increasing energy consumption in the long run.[46] Many environmental researchers believe that sustainable transport may require a move away from hydrocarbon fuels and from our present automobile and highway paradigm.[47][48][49]
The United States Environmental Protection Agency (EPA) is promoting the marketing of greener cars via the SmartWay program. The SmartWay and SmartWay Elite designation mean that a vehicle is a better environmental performer relative to other vehicles. This US EPA designation is arrived at by taking into account a vehicle's Air Pollution Score and Greenhouse Gas Score. Higher Air Pollution Scores indicate vehicles that emit lower amounts of pollutants that cause smog relative to other vehicles. Higher Greenhouse Gas Scores indicate vehicles that emit lower amounts of carbon dioxide and have improved fuel economy relative to other vehicles.
To earn the SmartWay designation, a vehicle must earn at least a 6 on the Air Pollution Score and at least a 6 on the Greenhouse Gas Score, but have a combined score of at least 13. SmartWay Elite is given to those vehicles that score 9 or better on both the Greenhouse Gas and Air Pollution Scores.
A Green Vehicle Marketing Alliance, in conjunction with the Oak Ridge National Laboratory (ORNL), periodically meets, and coordinates marketing efforts.[53]
Green car rankings
This section needs to be updated. Please help update this article to reflect recent events or newly available information.(February 2022)
Several automobile magazines, motor vehicle specialized publications and environmental groups publish annual rankings or listings of the best green cars of a given year. The following table presents a selection of the annual top pickings.
^Millikin, Mike. "Worldwide sales of Toyota hybrids surpass 9 million units; Prius family accounts for 63%". Green Car Congress. Retrieved 2016-05-22. The Prius family accounts for 63% of Toyota's total global cumulative hybrid car sales: 5.691 million units, consisting of Prius liftback: 3.733 million; Aqua, Prius c: 1.249 million; Prius α, Prius v, Prius +: 0.634 million; Prius PHV: 75,000.
^Organisation for Economic Co-operation and Development, Organisation for Economic Co-operation and Development. Working Group on Low-Emission Vehicles (2004). Can cars come clean?. OECD Publishing. pp. 84–85. ISBN978-92-64-10495-2.
^Kunstler, James Howard (2012). Too Much Magic; Wishful Thinking, Technology, and the Fate of the Nation. Atlantic Monthly Press. ISBN978-0-8021-9438-1.
^Gilbert, Richard (2010), "Transportation is the Post Carbon World", in McKibben, D (ed.), The Post Carbon Reader: Managing the 21st Century Sustainability Crisis, Watershed Media, ISBN978-0-9709500-6-2
^Black, W R (1996). "Sustainable transportation: a US perspective". Journal of Transport Geography. 4 (3): 151–159. doi:10.1016/0966-6923(96)00020-8.
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