Abstract: Battery electric vehicles are vehicles that run on electric motors that are fueled by a chemical battery and do not release greenhouses gas emissions



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Jimmy Szeto

jszeto@usc.edu

Cleaning Electric Vehicles

Abstract: Battery electric vehicles are vehicles that run on electric motors that are fueled by a chemical battery and do not release greenhouses gas emissions. Battery electric vehicles are growing in popularity as replacements for gasoline-powered vehicles. However, there are environmental concerns with how electric vehicle batteries are produced and how battery electric vehicles are charged. Before electric vehicles get on the road, there is already a carbon footprint created with manufacturing electric vehicle batteries. Lithium-ion batteries are the typical batteries used to power battery electric vehicles and there are tons of CO2 emissions created from producing lithium-ion batteries. The electricity used to recharge battery electric vehicles come from mainly combusting natural gas and burning coal because they are reliable sources of energy. Future battery technology could create more environmentally friendly and efficient batteries that could replace lithium-ion batteries. Renewable energy in the future could become more reliable energy sources to charge battery electric vehicles.

Biography: Jimmy is an undergraduate electrical engineer student at USC who has studied electric vehicles and their impact on the electric grid.



Introduction

Gasoline-powered vehicles have been an important source of transportation for many years allowing us to travel far distances, faster than if we were walking. However, the exhaust from the tailpipe of gasoline-powered vehicles releases tons of greenhouse gas emissions that contribute to major environmental problems, such as global warming. To reduce air pollution from our transportation system and meet our transportation needs, battery electric vehicles were designed to operate without a tailpipe and run on an electric motor that is fueled by a chemical battery. The electricity stored in the chemical battery powers all the functions of a battery electric vehicle. Battery electric vehicles are growing in popularity and it is expected that there would be more than 1.8 million battery electric vehicles on the road by 2020[1]. Although battery electric vehicles don’t have a tailpipe that release greenhouse gas emissions, there are still environmental problems associated with battery electric vehicles. Chemical, electrical, and environmental engineers are working to solve the environmental problems with the production of electric vehicle batteries and how these vehicles are charged.


The Life Cycle of a Battery

Before battery electric vehicles even get on the road, there is already a carbon footprint created with manufacturing the electric vehicle battery. Battery electric vehicles, such as a Tesla, typically use lithium-ion batteries that are designed by chemical engineers to be light-weight and have better performance than lead-acid or nickel-metal hydride batteries. The production of the lithium-ion batteries leaves a large carbon footprint and it begins with the mining of lithium. Then there is more energy and resources spent to process lithium before it can be used. The processed lithium is then brought to a battery plant to be combined together with copper and aluminum to assemble a lithium-ion battery. The processes and machinery used at battery plants to assemble the battery require large amounts of fossil fuels to build the battery parts. The mining and processing of lithium leaves behind a small carbon footprint compared to the large carbon footprint created at battery plants when copper and aluminum are used to assemble the battery.

[Include picture of battery manufacturing process]

The entire battery manufacturing process produces about 29,000 pounds of CO2 [2]. The amount of CO2 emissions created from a gasoline-powered by vehicle is about 14,000 pounds of CO2 so battery electric vehicles nearly double the amount of CO2 emissions of gasoline-powered vehicles during the manufacturing process [3]. The storage capacity of lithium-ion batteries degrade over time and the life of a lithium-ion battery is typically five to seven year before it needs to be replaced. Therefore, the production of new lithium-ion batteries to replace old lithium-ion batteries would create another twenty thousand pounds of CO2 and the production cycle will continue every five to seven years.


Pulling Up and Plugging In at the Fuel Station

After driving a battery electric vehicle and depleting the fuel in the battery, the battery electric vehicle will need to be stopped and recharged for the next trip. When battery electric vehicles are charged from the outlet of our house, there are greenhouse gas emissions released from using the electricity in our households. The electricity coming out of the outlets in our households have long transmission lines connecting the outlets to power generation stations. These power generation stations generate electricity either by burning coal or combusting natural gas. Whether it is an electric charging station in the city or an upgraded home charging system, the electricity still comes from generation stations that use coal or natural gas. When coal is burned to generate electricity, it releases nitrogen, sulfur dioxide, and carbon dioxide emissions. Natural gas releases nitrogen oxides, carbon dioxide, and small amounts of sulfur dioxide emissions when it is combusted to generate electricity. The emission released from natural gas power is about half the amount of emissions produced by coal power and coal power emissions can be as high as 2500 pounds per megawatt-hour of carbon dioxide from pulverized coal [4].

[Include a graph with greenhouse gas emission comparisons from coal and natural gas]

Hence, using electricity to recharge battery electric vehicles does not eliminate greenhouse gas emissions that used to come out of the tailpipe from gasoline-powered vehicles. Instead, greenhouse gas emissions are relocated to the power generations stations so greenhouse gas emissions are released every time an electric vehicle needs to be recharged.


Charging an electric vehicle uses about 6.6kW of power and it uses almost as much electricity as a house that typically use 7kW [5]. When we charge our electric vehicles in our households, we use double the amount of electricity because the electronic appliances in our household need to use electricity as well. Hence, an additional electric vehicle in a household would also double the amount of greenhouse gas emissions. As the nation transitions from gasoline-powered vehicles to battery electric vehicles, more electricity needs to be generated to power the growing amount of electric vehicles out in the market. This causes utility providers to burn more coal and natural gas to generate more electricity to meet the increase in electricity demand.


Electricity Releases Foul Gases

Electricity is the fuel that replaces gasoline in battery electric vehicles. The problem with using electricity is most of the electricity in the United States is generated with coal and natural gas, which creates greenhouse gas emissions when burned or combusted to generate electricity. In 2012, coal power contributed to 37% of the United States’ power and natural gas generated another 30% of the nation’s power [6]. Both coal and natural gas are fossil fuels that have been providing electricity for our nation for many years. Coal is used to generate electricity because it is a reliable source of power and it is a cheap and abundant fossil fuel. Natural gas is the most efficient source of power and it is a reliable source of energy as well. Presently, there has been a decrease in coal power and a transition towards more natural gas power because environmental and electrical engineers found that natural gas produces fewer emissions than coal power and is more efficient. However, the problem with generating emission free electricity still hasn’t been solved and renewable energy sources aren’t able to supply enough power compared to natural gas and coal power.


The popular renewable energy sources are solar and wind, but they both contributed less than 5% of the United States’ power in 2012 [6]. Another problem that electrical engineers found is that some renewable energy sources such as wind and solar power are very dependent on the weather so they aren't very reliable. If the sun is shining and the wind isn’t blowing, then there is no solar and wind power for us to use as electricity. Battery electric vehicles need to be able to be charged any time of the day and only coal and natural gas are able to provide a continuously available supply of electricity throughout the day.

Powering the Future of Transportation

To reduce the environmental impact of charging electric vehicles and accommodate the increasing electricity demand, renewable energy sources are needed to replace coal and natural gas power. Solar and wind power have zero emissions and there is a lot of potential for both of them to grow. There are wind turbines that have solar cells covering the blades of the wind turbine to increase overall efficiency by combining wind and solar power. The research in solar cell technology will make solar cells more efficient and cost effective. Further development in the blades of wind turbines can make wind turbines more efficient in the future. Computer scientists and power engineers are looking into the future of the electric grid known as the Smart Grid, which integrates information technology to recharge battery electric vehicles more efficiently while using less fossil fuels and more renewable energy.


In the future, supercapacitors could possibly replace the lithium-ion batteries in battery electric vehicles because they have longer battery lives and the storage capacity doesn’t degrade so they don’t need to be replaced as often. They also can be charged and discharged faster than lithium-ion batteries. Further research needs to be done to increase the storage capacity of supercapacitors before they can be viable replacements for lithium-ion batteries. There are also chemical and electrical engineers trying to develop a sodium-ion battery made out of wood. This efficient prototype battery is much cheaper to produce and it is more environmentally friendly. Currently, the short life-cycle of the sodium-ion battery needs to be solved before the sodium-ion battery is released into the market. The future of electric vehicle charging and battery technology will make battery electric vehicles more environmentally friendly.

References

[1] R. Martin. "Navigant Research." Navigant Research More than 18 Million PlugIn Electric Vehicles Will Be Sold in the Largest 102 US Cities From 2012 to 2020. Internet: http://www.navigantresearch.com/newsroom/more-than-1-8-million-plug-in-electric-vehicles-will-be-sold-in-the-largest-102-u-s-cities-from-2012-to-2020 [Oct. 26 2013].

[2] Matto. "Electric Cars Don't Use Fossil Fuel, but What's the Environmental Impact and Life Cycle of the Batteries?" Internet: http://carbonpig.com/article/electric-cars-dont-use-fossil-fuel-whats-environmental-impact-and-life-cycle-batteries [Oct. 25 2013].

[3] B. Lomborg. (2013, Mar.). "Bjorn Lomborg: Green Cars Have a Dirty Little Secret." The Wall Street Journal. [Online], Available: http://online.wsj.com/news/articles/ SB1000142412788732412850457834691399491447211 [Oct. 26 2013].

[4] "Air Emissions." EPA. Environmental Protection Agency, Internet: http://www.epa.gov/

cleanenergy/energy-and-you/affect/air-emissions.html, [Oct. 23, 2013].

[5] S. Lang. "Electric Vehicles and the Smart Grid: Charging Forward!" Electrical Energy Online. Electric Energy Publications Inc., Available: http://www.electricenergyonline

com/?page=show_article&article=542 [Oct. 22 2013].

[6] "What Is U.S. Electricity Generation by Energy Source?" EIA. Available: http://www.eia.gov/tools/faqs/faq.cfm?id=427 [Oct. 25 2013].

[7] "Potential Environmental and Human Health Impacts of Rechargeable Lithium Batteries in Electronic Waste." - Environmental Science & Technology (ACS Publications). Internet: http://pubs.acs.org/doi/abs/10.1021/es400614y [Oct. 25 2013].

[8] J. Conca. (2013, July) "Are Electric Cars Really That Polluting?" Forbes. Forbes Magazine, [Online] Available: http://www.forbes.com/sites/jamesconca/2013/07/21/are-electric-cars-really-that-polluting [Oct. 26 2013].

[9] N. Nadir. "Are Electric Cars Green? The External Cost of Lithium Batteries." Internet: http://theenergycollective.com/nnadir/221226/green-electric-car-actually-green-external-cost-lithium-batteries [Oct. 23 2013].

[10] "Will Electric Vehicles Really Reduce Pollution?" Internet: http://www.physics.ohio-state.edu/~wilkins/writing/Samples/policy/voytishlong.html [Oct. 26 2013].



[11] M. Heil. (2013, July) "A Battery Made of Wood?" UMD Right Now. [Online]. Available: http://www.umdrightnow.umd.edu/news/battery-made-wood [Oct. 26 2013].


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