Example Of Natural Gas-Powered Cars Argumentative Essay

Accusations of creating processes and artefacts that have a negative impact on the natural environment have often been levelled against engineers. This essay reviews available literature to assess the validity of this accusation with reference to natural gas-powered cars, and reviews the practicality and sustainability of this fuel type for vehicle propulsion.
Natural gas is mainly available as either compressed natural gas (CNG) or liquefied petroleum gas (LPG). CNG is stated to be the most suitable to fuel cars and other vehicles because it is both the cheaper and the cleaner choice. It is predominantly methane and is typically sourced from wells – either wells drilled to tap underground gas reserves or as a by-product obtained from oil wells or from wells drilled into methane-bearing coal seams. Although CNG is said to be the most suitable for powering vehicles, LPG is also widely used for that purpose because it requires less space than CNG in the vehicle for the fuel tank. Both CNG and LPG are cheaper than either petrol or diesel. It is also claimed that CNG-powered vehicles have lower costs of maintenance. Unlike petrol or diesel, CNG neither contaminates nor dilutes the oil in the engine’s crankcase, so the oil lasts longer before it needs changing (“CNG vs. LPG” n.d.).
In many countries including the UK, the choice of fuels now includes LNG (liquefied natural gas). This is the same basic fuel as CNG, but must be cooled to below -160 degrees C to become liquid and must be stored at that temperature under pressure of about 8 atmospheres. That has adverse consequences for its use as a vehicle fuel, in that the fuel tank has to be double-insulated and include a venting system. The tank is therefore very large, making LNG more suitable for heavy vehicles such as trucks and buses. However, even though the fuel efficiency is only about 60 percent of diesel (CNG is only about 25 percent as efficient as diesel), running costs are lower due to favourable rates of excise duty and road tax. Additionally, natural gas-powered vehicles used in the London area can be exempt from imposition of the London Congestion Charge (“Liquefied Petroleum Gas (LPG)” 2013).
According to Lane (2015), CNG or LPG as vehicle fuel is better overall for the environment, due to their clean properties causing lower emissions, although he notes that because methane is a greenhouse gas, that fact should be taken into account when considering the environmental impact of CNG. However, he claims that taking that into account, as well as the fact that LPG fuel consumption is about 30 percent greater than petrol, cars running on dual fuel systems (petrol and LPG – switchable) are around 10 to 15 percent cleaner than petrol and in that regard comparable with diesel emissions (Lane, 2015).
Lane also provides more detail about the benefits of CNG or LPG in terms of reduced emissions, stating that the unburned methane and other hydrocarbons produced by CNG-powered cars “contribute less to tropospheric-ozone formation than do the volatile organic compounds present in petrol exhaust emissions” and that the best reductions are obtained when cars run only on CNG or LPG (i.e. not using a switchable fuel system) (Lane, 2015).
A 2014 Consumer Report discusses the advantages and disadvantages of compressed natural gas (CNG) as a vehicle fuel, but comes out heavily in its favour, mentioning that compared with petrol it produces far fewer emissions while offering comparable fuel economy and only marginally inferior acceleration. In terms of energy cost, it is also cheaper than petrol. According to the US Environmental Protection Agency (EPA), the emissions of carbon monoxide (CO) are at least 90 percent lower than those from petrol, and nitrogen-oxide (NOx) emissions are between 35 and 60 percent lower. Furthermore, non-methane hydrocarbon emissions from CNG can also be lower in the order of 50 to 75 percent, and CNG produces fewer carcinogenic pollutants and almost no particulates (“The natural-gas alternative” 2014).
As regards, sustainability of natural gas as a vehicle fuel, it is a fossil fuel, so by definition can be expected to be limited in quantity and availability, just like oil or coal. However, the gas can be created in synthetic form (SNG or synthetic natural gas) from biomass, making it a renewable energy source. A Dutch study by Zwart et al. (2006) has confirmed the feasibility of manufacturing SNG on a large scale, and forecasts that future costs will be comparable with natural gas, albeit costs of either or both will be affected by various government subsidies that may or may not be applied (Zwart et al., 2006 p.60).
An argument sometimes mentioned against using any of these fuels for cars is the initial capital cost – either the premium cost of purchasing the car new as a monofuel vehicle – or converting an existing petrol-powered car to gas power (usually to make it a bi-fuel car, switchable between gas and petrol). However, those costs can be offset to produce an overall cost saving if the car is used to cover high mileages, according to Wright (2013), writing for the Financial Times. The fleet sales sustainability manager at Ford (US) is quoted as stating that 60,000 miles is about the breakeven point – a mileage that some fleet users accumulate in 24 months or less. In the US for example, where CNG supplies are plentiful, Wright compares the price per gallon of petrol ($3.40) with the “gallon equivalent” of CNG at $1.25. Wright also cites the fact that suppliers are prepared to sign ten-year contracts as a strong indication of the future availability of the gas (Wright, 2013).
It should also be taken into consideration that because the majority of any negative environmental impacts associated with natural gas occur at the time of initial drilling and extraction, those impacts are temporary in nature and for the most part disappear once the wells are established and in production – perhaps for many years. Thus – when considering the bigger picture – the environmental impacts may be viewed as almost entirely positive.
Conclusions

References:

“CNG vs. LPG.” (n.d.). Diffen. Available at: http://www.diffen.com/difference/CNG_vs_LPG
“Environmental Impacts of Natural Gas.” (n.d.). Union of Concerned Scientists. Available at: http://www.ucsusa.org/clean_energy/our-energy-choices/coal-and-other-fossil-fuels/environmental-impacts-of-natural-gas.html#.VRPwird0y00
Lane, Ben. (Mar. 2015). “LPG and natural gas.” Next Greencar. Available at: http://www.nextgreencar.com/lpg-cng.php
“Liquefied Petroleum Gas (LPG), Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG).” (Updated May 2013). Envocare. Available at: http://www.envocare.co.uk/lpg_lng_cng.htm
“The natural-gas alternative: The pros & cons of buying a CNG-powered car.” (Updated Apr. 2014). Consumer Reports. Available at: http://www.consumerreports.org/cro/2012/03/the-natural-gas-alternative/index.htm
Wright, Robert. (Dec. 2013). “Road opens up for CNG vehicles in US.” The Financial Times. Available at: http://www.ft.com/intl/cms/s/0/9f06bea8-69ea-11e3-aba3-00144feabdc0.html#axzz3VUITu1c5
Zwart, R.W.R, Boerrigter, H., Deurwaarder, E.P., van der Meijden, C.M., & van Paasen, S.V.B. (Nov. 2006). “Production of Synthetic Natural Gas (SNG) from Biomass.” Energy Research Centre of the Netherlands (ECN). Available at: http://www.ecn.nl/docs/library/report/2006/e06018.pdf