United States Oil Consumption – Macroeconomics Essay
The United States consumes about 131 billion gallons of gasoline per year. That equates to about 118 million barrels of oil daily. Considering there is about 100 million households in the United States, that is 3.6 gallons per household daily. This amount of gasoline cannot be supplied for an extended amount of time. It is also not safe to rely so heavily on such a scarce resource. This is the reason alternative fuels are being designed and tested to take the place of petroleum based fuels.
One of the most promising alternative is electric motors. This is often done by converting a normal gasoline powered car into an electric powered car. Electric motors are near silent and drastically reduce emissions. The electric motor is powered by a controller which is powered by fifty lead-acid rechargeable batteries. These are wired into two sets of fifty which creates three hundred volts of direct current. Additional electric motors are needed to run accessories that would otherwise be run by the gasoline engine. These accessories include air conditiong, power steering pump, and water pump. The power brakes which relied on the vacuum created by the intake stroke of the piston in the four stroke gasoline engine are now supplied vacuum with a vacuum pump. Heating the cabin is now done by an electric water heater instead of having engine coolant routed to the cab. It costs one dollar to fully charge the vehicle, which equates to two cents per mile. If a gasoline powered car gets thirty miles per gallon and gasoline costs $1.20 per gallon, the cost per mile is about four cents. The major drawbacks to this design would be the limited range of the vehicle on a single charge (50 miles) and slow accelleration (0-60mph in 15 seconds). You can increase the range of the vehicle, but you also sacrifice accelleration. As it is now, the batteries weigh about 1,100 pounds and last roughly 20,000 miles. To replace the batteries it would cost $2000, so the batteries equate to about ten cents per mile.
A slight modification to this design is the fuel cell. Instead of batteries, it gets its electricity from a fuel cell powered by pure hydrogen. The fuel cell is an electrochemical conversion device that converts hydrogen and oxygen into water, creating electricity and heat. Fuel cells are usually classified according to the type of electrolyte used. The most promising type of fuel cell is the proton exchange membrane fuel cell (PEMFC). Each cell only produces 0.7 volts, so many cells must be connected in series to increase the output to a useable voltage. These cells operate at about 176 degrees fahrenheit, which is in the ballpark of the operating temperature of a conventional gasoline engine. Gasoline engines normally operate from 160-210 degrees fahrenheit, so heat isnt an issue. The power density of a PEMFC lets a fuel cell the size of a suit case to properly power an automobile. The only drawback to fuel cells is the availability of hydrogen. It is very hazardous to transport and store, so a hydrogen refueling station is not practical. Other fuels can power fuel cells when they are converted into hydrogen by a reformer with less efficiency than pure hydrogen, but have much greater availability. These fuels include natural gas, propane, and methanol. When pure hydrogen is used, the fuel cell operates at 80% efficiency. When methanol is used to power the fuel cell, this number drops to 30-40%. Knowing that a gasoline engine operates at about 20% efficiency, these numbers are very good.
Another alternative is the air-powered car. These cars convert compressed air into mechanical energy. The two cylinder compressed air engine can run on either compressed air or internal combustion. The compressed air is stored in carbon fiber wrapped tanks at a pressure of 4,351 pounds per square inch. The air travels through an injector which is aimed at the piston. The expanding air pushes the piston down, turning the crankshaft and moving the car. The only emission from this engine is air, so it is considered a zero pollutant engine. Internal combustion is used at high speeds to save the compressed air for low speed driving where engines produce the most pollutants. The range of these cars is about 125 miles and have a top speed of about 60 miles per hour. Using a household electrical source, it takes about four hours to refill the tanks. A rapid three minute refill can be done with a high pressure pump. The engine still requires oil to lubricate the piston and crankshaft, but only 0.8 liters that has to be changed every 31,000 miles. This is considerably less than gasoline powered cars which use about 5 liters of oil every 3000 miles.
Many have recognized our over reliance on petroleum and are trying to think of ways to preserve this non renewable resource with ones that are renewable. If we wait until all the petroleum is gone before we seek a solution, we will no longer be able to make plastics as they are petroleum based. Plastics are vital to our everyday life, from pens to computers to life saving hospital equipment. Plastic is also used for specialty purposes such as bullet proof vests and glass where there are no materials suitable to replace it for the application. Without plastic, there may be an even fewer amount of possible solutions to petroleum. All of the alternatives discussed have used plastic in one way or another because it would be extremely difficult to cut out the use of petroleum all together. The focus is to control the consumption of petroleum by the vehicle instead. I am excited to see what the future holds in store for transportation.
Bibliography
How much gasoline does the United States consume in one year?
by Marshall Brain
http://auto.howstuffworks.com/question417.htm
How Fuel Cells Work
by Karim Nice
http://auto.howstuffworks.com/fuel-cell.htm
How Air-Powered Cars Will Work
by Kevin Bonsor
http://auto.howstuffworks.com/air-car.htm