by JP Kiefer
Electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and fuel cell vehicles all offer promising alternatives to the conventional vehicle in reducing greenhouse gas emissions. These alternatives may not be as beneficial as they seem on first glance, however. While electric, hybrid-electric, and fuel cell vehicles all promise to minimize greenhouse gas emissions from their daily use, Gau and Winfield (2012) point out that each vehicle’s life cycle assessment needs to be computed before jumping to the conclusion that hybrid vehicles minimize greenhouse gas emissions. The life cycle assessment analyzes the greenhouse gas emissions from two cycles: a vehicle life cycle that includes vehicle assembly, maintenance, dismantling, and recycling and a fuel life cycle that consists of fuel extraction, processing, distribution, storage, and use. These alternative vehicles are the products of a larger volume of greenhouse gas emission from the vehicle life cycle due to additional energy consumption involved with the batteries and other additional parts that go into the more advanced technologies. Electric, hybrid electric, and plug-in hybrid vehicles can also contribute to greenhouse gas emissions when the energy used to charge the batteries does not come from a clean energy source. Gau and Winfield calculate that alternative vehicles do consume less energy than conventional vehicles, which consume an estimated 3600kJ/km in their life time, compared to a mere 2250kJ/km by hybrid electric vehicles or 3000kJ/km by extended range electric vehicles.
After determining that alternative vehicles do appear to be more environmentally friendly than conventional vehicles, Gau and Winfield attempted to determine if such vehicles are also friendlier on the wallets of consumers. Alternative vehicles tend to come with larger price tags and the possibility of larger maintenance costs when compared to conventional vehicles, but their drivers will also save a considerable amount of money refueling as well. Electricity costs, which tend to remain relatively stable in the US, were estimated at $0.13/kWH, while the volatile price of gas was more difficult to estimate for the future. Results were computed for both a minimum of $2.00/gal and a maximum of $6.00/gal to show a range within which total costs of a vehicle over a lifetime might be. Gau and Winfield calculated that if gas prices are low, conventional vehicles might actually be cheaper than alternatives with a cost of just over $0.1/km. Hybrid electric vehicles were just slightly more expensive than this, but the remainder of alternative vehicles were significantly more expensive, especially if driven for many miles between charges. These alternative vehicles were estimated to cost between $0.15/km and $0.20/km.
If gas prices rose to their maximum projected cost of $6.00/gal, the alternative vehicles become more cost-efficient, especially when recharged frequently. Alternative vehicles hovered just above the price of $0.15/km, whereas conventional vehicles cost an estimated $0.20/km. Overall, Gau and Winfield did not declare a “best vehicle,” but pointed out that the hybrid electric vehicle achieves the lowest energy consumption and emissions, but that it would not make economic sense if gas prices remain low.
Gao, L., Winfield, Z., 2012. Life Cycle Assessment of Environmental and Economic Impacts of Advanced Vehicles. Energies 5, 605-620.