Strategies for Atmospheric Impacts of Road Transport
Consider the prospects for using alternative fuels to reduce the atmospheric impacts of road transport
As our world has globalised, our society has become increasingly interconnected through breakthroughs in our ability to travel from one area to another. This interconnectedness has been of economic and social benefit for people all over the world, so much so that we refer to our world as “shrinking” due to the ease and quickness of transport compared to that of the past. However, with this development and increase in transport our climate has been impacted.
In the past exhaust gases from road traffic had, and still has, negative effects on air quality as road transport are major causes of nitrogen oxide pollution. Due to the introduction of U.S Clean Air Act of 1970 mass production of catalytic converters started in 1975 in the US and was introduced to Europe ten years later. Still, road transport became increasingly desirable for both private and business use. About 38% total fuel consumed is diesel, 60% is gasoline and 1% and 0.7% is gaseous fuels and biofuels. OECD countries are responsible for two thirds of the worlds fuel consumption (Uherek et al, 2010).
Road transport vehicles produce a quantity of different harmful pollutants including nitrous oxides and particulate matter. These emission levels are particularly high in urban environments where the population is dense. The European union has set limits to the amount of pollution that populations should consume yet these limits are still breached in the densest areas where motor vehicles tend to accumulate.
NOx comprises a mixture of nitric oxide (NO) and nitrogen dioxide (NO2). In the air NO is rapidly converted to NO2 which will also react in the air to form nitrate particles and ozone (O3). NO2 is a toxic gas harmful for health. NOx emissions also contribute to acidification and eutrophication, causing serious damage to ecosystems. Road transport accounts for a third of NOx emissions and is the dominant source in urban heavily trafficked areas. The average contribution of local traffic to urban NO2 and PM10 concentrations is estimated at 64% and 34%, respectively. It is estimated that around 10% of the EU urban population is exposed to NO2 levels above the EU limit value and that approximately 80% of the urban population is exposed to PM10 levels exceeding the WHO guideline value. https://www.transportenvironment.org/what-we-do/air-pollution/road-vehicles
People know that road transport is harmful to the environment and yet they continue to use cars. The number of cars used is likely to only increase as third world countries develop and populations continue to rise, meaning that simply using less cars is an unrealistic solution. With this it is clear that if we are going to lower the pollution levels of cars we need to either improve their efficiency or stop using the harmful fuels they burn. Development of alternative fuels for road transport vary depending on the country and their economic standing. When oil prices went up in 1970 it promoted new interest in the idea of alternative fuels. Countries such as Brazil and the US began considering biofuels as a replacement but after a century of research and experiments alternative fuel sources still accounts for less than 2 percent of the worlds road transport fuel consumption. This 2 percent is limited to Brazil, the US and the European Union. The escape from traditional fuel sources has been found to be extremely difficult in the transport sector compared to others (Johnston and Silveira, 2014).
One of the most commonly referred to of alternative fuels is ethanol, the most common biofuel. With the chemical formula C2H5OH it is the same alcohol found in alcoholic beverages. Used by blending it into gasoline so that it makes up 5 to 10 percent of the mixture. When looking at the characteristics of ethanol it has a lower energy content than gasoline. To reach the same distance you would require a third more ethanol than what you would need of gasoline. http://www.consumerenergycenter.org/transportation/afvs/ethanol.html
Ethanol is renewable unlike our finite oil resource. It’s the product of various plant materials, usually of corn, so there isn’t a massive issue around being able to produce it. Ethanol works best when blended with gasoline as it has a high-octane number, fuel has a minimum octane number to ensure its drivability. http://www.afdc.energy.gov/fuels/ethanol_fuel_basics.html
Figure 1 – Global Ethanol Production http://www.afdc.energy.gov/data/10331
The above graph Figure 1 shows the production of ethanol in different countries over the years, what this graph is able to tell us is that production has been steadily growing with a few dips most likely down to times when other fuels were cheaper. We can also see that the USA and Brazil are consistently the greatest producers. Interest in biofuels has been growing and company’s such as shell and BP are viewing them as a possible future replacement for gasoline. Ethanol made from corn creates 25 percent more energy than that which is required to grow the corn and distil into ethanol. Although ethanol creates a more effective fuel it doesn’t resolve the problem that we are still heavily reliant on fossil fuels for road transport. Even though it may produce slightly lower greenhouse gas emissions it’s still not enough to be sustainable (Hordeski, 2009).
Electric cars are more in production now than ever before with people owning and driving them, many electric cars claim zero emissions however it is argued that electric cars can be as damaging as regular gasoline powered cars. Electric cars rely on being charged to be powered. This electricity to do so comes from the local electricity network. The energy in this network has come power plants that aren’t emission free. In California in 2015 60 percent of electricity came from burning fossil fuels and wind and solar only accounted for and meagre 14 percent. If this is the case than does using an electric car really improve on how it impacts the atmosphere? One thing that electric cars do, however, is make air quality better in urban areas which would in turn lower pollution below the European Union’s limit meaning healthier air for city residents. At night there is when electricity produced is cheapest, from natural gas, nuclear and hydroelectric dams however this is not the greenest option and people are more likely to charge their cars overnight, solar is of course only available during the day when there’s sun meaning that it’s greener to charge cars during the day. Due to the grid, however, there is almost no capacity to store power created from solar and wind meaning energy is used as its produced. The only hope for this problem is future development of the grid to be able to store energy from renewables (Deb, 2016). https://www.theguardian.com/environment/2016/dec/08/electric-car-emissions-climate-change
Natural gas is an odourless and colourless gaseous mixture of hydrocarbons. Liquefied natural gas and compressed natural gas is used for ease of transportation and both used as motor fuel. Natural gas is used for its availability, low cost and its benefits of emission. Vehicle that are designed to run on LNG and CNG drive as effectively as those using petroleum http://www.afdc.energy.gov/fuels/natural_gas_benefits.html
In conclusion, it is clear that we must look towards alternative methods of fuel in the hopes of lowering our carbon footprint as without doing so we will only continue to produce more and more pollution. When it comes to using biofuels and natural gas they may undoubtedly provide certain benefits and improvements but in the long term they are also non-sustainable due to ethanol currently just being an additive to a finite petroleum and natural gas being a finite resource itself. Electric would be desirable especially if we were able to rely completely on renewable fuel sources such as solar and wind in the future. However, all have their flaws and only further development will create the fuel source of the future.
Uherek, E et al. (2010). Transport impacts on atmosphere and climate: Land transport. 44th ed. Elsevier, pp.4772-4816.