|Fig. 1: A Tesla charging station. Wikimedia Commons)|
Greenhouse gasses have proven to have a negative effect on our environment. Many nations have set out goals to lower these emissions in attempts to help save our planet. In many countries the sectors that produce these emissions are defined as industrial, residential, commercial and transportation.  This research will specifically look into carbon dioxide emissions in the US and the potential to combat these extreme amounts of emissions. From 1973 (and before) to 1999 the industrial sector produced the most carbon dioxide emissions.  The industrial sector was at its height in 1973 when it produced 1,884 million metric tons of carbon dioxide emissions.  After the 1970- 80s period the industrial sector has seen a steady decline in emissions, in 2016 producing less than 350 million metric tons than 40 years prior.  The decline that has been seen is a product of developing green energies, increased energy efficient products and harnessing sustainable sources of energy (wind/solar). While its great to see this decline from the industrial sector an increase in the transportation sector is worrisome. In 1998 the transportation sector edged out the industrial sector to produce the most CO2 emissions.  Since that year, where transportation produced 1,782 million metric tons of CO2, it has increased, reaching its height in 2005 when it produced 2,021 million metric tons.  Since its height it has fallen 200 million metric tons, but remains the leading source of CO2 emissions in the US. 
The transportation sector includes all motives of transportation, ranging from airplanes, boats and everything in between. The three subsectors of the transportation sector are natural gas, petroleum, and retail electricity. Typically, petroleum accounts for 90% of the production.  Petroleum consists of Aviation Gasoline, Distillate Fuel, Oil, HGL, Jet Fuel Lubricants, Motor Gasoline and Residual Fuel Oil. Not surprisingly, motor gasoline produces most of the CO2 emissions.  In 2011 the US population owned nearly 243 million vehicles, this increasing number of cars has a great impact on the amount of CO2 that is produced.  In 2017 motor gasoline accounted for 1,007 million metric tons of the 1,702 produced that year (just 11 months were recorded).  Motor gasoline has constantly been the leading contributor to CO2 emissions.  With the development of electric vehicles, companies like Tesla have found ways to prevent these emissions from growing.
The growth of developing technologies has helped reduce these emissions. As electric vehicles continue to become more reliable and fuel efficient, more US car owners are converting to electric. In 2016 there were nearly 160,000 new electric vehicles registered in the US, the year before that there was 114,000.  This number continues to grow as electric vehicles become increasingly more affordable and dependable. Tesla is aiming to sell a million cars annually by the year 2020.  While the number of cars continues to grow, accessibility increases. The US has the second most charging stations in the world, behind China (see Fig. 1).  As the popularity, dependability and accessibility increases, the number of vehicles will only continue to rise, in turn lowering the amount of CO2 emissions.
The solution to lowering the emissions from the lead polluting sector in the US is right in front of us. This is not a solution that will happen overnight, but with time there is reason to be optimistic. Technology will continue to improve and hopefully we will see a continued rise in electric vehicles in the US, resulting in a decline of CO2 emissions. Companies like Tesla and Toyota continue to pave the way toward a lower carbon dioxide future. A future that we need to see, sooner rather than later.
© John Toner. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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