Question

The transportation sector in the United States presently runs almost exclusively on petroleum-based derivatives (gasoline, diesel, fuel). Research the following alternatives.

Hybrid

Diesel & biodiesel

Flex-fuel Ethanol

Natural gas

Propane

Hydrogen

Electric

Fuel cell

Prepare a one-page paper outlining what you believe may be viable alternatives to the use of fossil fuels. May be assigned as a team or an individual assignment.

Answer 1

Viable alternatives to the use of fossil fuel-

Fossil fuels are the major sources of energy today in our lives. They find extensive use in transportation, industries, electricity generation and most of the applications where energy is required. Through fossil fuels energy is obtained by their combustion and sometimes this energy is converted to other forms of energy and sometimes used directly. The combustion of these fuels releases exhausts in the form of CO₂, CO, SO₂ and other harmful greenhouse gases which are capable of depleting the ozone layer and are the major cause of climate change. The problem with the use of fossil fuels is not just limited to pollution. Their amount of reserves on earth are also limited and at their present rate of use they are quickly heading towards complete exhaustion. So, to slow down their use and protect the environment, research is going on about alternatives to their use.

1. Fuel Cells- Fuel cells are the electrochemical cells that convert the energy released from the reaction of Hydrogen and Oxygen to electricity. The biggest advantage of using fuel cells is that they do not create any exhausts because the end product is water and energy, the reaction given as-

H₂ + O₂ ---> H₂O + energy

Fuel cells are of different types but all have the same basic framework consisting of 2 electrodes i.e. the cathode and the anode along with the electrolyte. Reactions take place at these electrodes to release the energy. Sometimes catalysts are used to speed up these reactions.

2. Natural Gas- Natural gas is also finding extensive use today in vehicles in the form of CNG (Compressed Natural Gas). This alternative is slowly gaining popularity as it is a comparatively cleaner fuel than gasoline. The primary constituent of natural gas is methane (CH₄) but it also includes some amounts of ethane(C₂H₆), propane (C₃H₈) and other heavier hydrocarbons. Natural gas is also included in fossil fuels as it is found along with the reserves of crude.

3. Propane- Propane(C₃H₈) is used in domestic supplies of energy and some industrial supplies as well in the form of LPG (Liquefied Petroleum Gas). The propane gas is compressed to a transportable liquid i.e. LPG and used for energy supply in homes. Since Propane is obtained as a by-product from the refining of crude and the processing of natural gas, it also comes in the category of fossil fuels. The energy is produced by the reaction-

C₃H₈ + 5O₂ -----> 3CO₂ + 4H₂O + heat

4. Flex Fuel- Flex fuel consists of a mixture of gasoline and ethanol. Flex fuel vehicles are the vehicles having an internal combustion engine capable of using Flex fuel i.e. a mixture of gasoline and ethanol as a fuel. These vehicles are at par with the ordinary combustion engines, the only difference being that the calorific value of ethanol is lesser than that of gasoline. Hence, the mileage of Flex fuel vehicles is lesser than that of ordinary gasoline powered vehicles.

5. Diesel and Biodiesel- Diesel is the fossil fuel obtained from processing of crude. It has somewhat better fuel efficiency than gasoline but the contribution to pollution is almost the same. Biodiesels are similar to fossil fuels but they can be produced from vegetable oils, animal fats/oil, waste cooking oil and tallow. The biggest advantage of using biodiesel as a fuel is that it is 'carbon neutral'. This means that the amount of carbon released in the form of CO₂ by its combustion is the same amount of carbon it absorbs in the form of CO₂ absorption when the oil crop is grown. The process used to convert the various oils into biodiesel is called transesterification.

6. Electricity- The use of electricity in automobiles is quickly becoming popular because they are not only a cheaper fuel but also have no problem of pollution. With companies like Tesla making strides in the use of electricity as an alternative to the conventional gasoline, we expect the use of electricity to go up further in the coming days. But, today electricity is produced majorly from the burning of coal (fossil fuels). This offsets the advantage of no exhausts released from the electric cars. Hence, we have to find and apply other sources of energy. These can include solar energy, wind energy, geothermal energy, etc. along with the sources discussed above.

7. Hybrid vehicles- These are the vehicles that use two or more different types of power. For eg. an IC engine driving an electric generator to power an electric motor. These types of vehicles come in all forms, starting from mopeds, electric bicycles and electric kick scooters to all the way to hybrid powertrains.

8. Hydrogen- The hydrogen gas is a clean high calorific value fuel, which can be used in the form of both an electrochemical cell (as discussed above-fuel cells) or in combustion engines. The energy is released by its reaction with oxygen releasing water. Hydrogen fuel is used in high energy applications today like powering a rocket.