What is advantage And Disadvantage of Hydrogen ?

What is advantage And Disadvantage of Hydrogen ?

Hydrogen

A number of companies have built automobiles with prototype or modified engines which operate on hydrogen.
— A H2-powered car being developed in Melbourne University Department of Mechanical Engineering is achieving 40 percent energy saving over conventional petrol engine. The car is a converted Ford Cortina Wagon which carries enough fuel in 4-cylinders to travel upto 50 km at a speed of 130 km/h.
— German cars are so developed that they can be converted for driving either gasoline or H2 by making a few simple adjustments. Presently a few vehicles are running on road as there are very few public filling stations for liquid H2. Many more are planned for future.

Advantages of hydrogen as I.C. engine fuel :

1. Low emissions. Essentially no CO or HC in the exhaust as there is no carbon in the fuel. Most exhaust would be H2O and N2.
2. Fuel availability. There are a number of different ways of making hydrogen, including electrolysis of water.
3. Fuel leakage to environment is not a pollutant.
4. High energy content per volume when stored as liquid. This would give a large vehicle range for a given fuel tank.
5. Hydrogen-air mixture burns ten-times faster compared to gasoline-air mixture. Since the burning rate is considerably high, it is more preferred in high speed engines.
6. Hydrogen-ignition limits are much wider than gasolines. So it can burn easily and give considerably higher efficiency.
7. Hydrogen has high self-ignition temperature (S.I.T.) but very little energy (1/50 th of gasoline) is required to ignite it.
8. The exhaust heat can be used to extract H2 from the hybride reducing the load engine.
9. Besides being a relatively clean burning renewable source, H2 as I.C. engine fuel is very efficient as there are no losses associated with throttling.

Disadvantages :

1. The handling of H2 is more difficult and storage requires high capital and running cost particularly for liquid H2.
2. Difficult to refuel.
3. Poor engine volumetric efficiency. Any time a gaseous fuel is used in an engine, the fuel will displace some of the inlet air and poorer volumetric efficiency will result.
4. Fuel cost would be high at present day technology and availability.
5. Can detonate.
6. High NOx emissions because of high flame temperature.
7. In hydrogen engines there is a danger of back fire and induction ignition which can melt the carburettor. Therefore in H2-fuel system, flame traps, flask back arresters are necessary. Additionally, crankcases must be vented to prevent accumulation of explosive mixtures.

What is advantage And Disadvantage of Biogas ?

Biogas:

Advantages of gaseous fuels :

1. Easily compressed and stored.
2. Easily carried through pipes.
3. Easy starting of engines.
4. Easy to maintain A/F ratio in multi-cylinder engines, as compared to liquid fuels.

Disadvantages :

1. High cost (on the basis of energy content).
2. High purifying cost.
3. Storage volume per unit energy very large.
4. As compared to engines using liquid fuels, the size and weight of the engine (kg/kW) is considerably large.
5. The cost (capital and running) of the plants manufacturing gases is considerably high.

What is advantage And Disadvantage of using Alternative Fuels ?

Advantages and Disadvantages of using Alternative Fuels

Advantages of using alternative fuels :

1. Alcohols can be produced from highly reliable and long-lasting raw material sources like sugarcane, starchy materials, corns, potatoes etc. Thus they are renewable energy sources.
2. Biogas plants can be conveniently and economically installed in village and farms.
3. Manufacture of biogas from cow-dung will give, as a byproduct, manure of very high quality for use in the-farms.
4. Natural gas is available in plenty.
5. Coal gas is produced by coal gasification, and coal is abundant to last much longer than the liquid petroleums.

— Alcohols, biogas and natural gas have much higher octane number, and are suitable for use in S.I. engines with little modification. There is less problem of knocking or detonation. Higher compression ratios can be used to give more power and increased thermal efficiency.

6. The exhaust from engines using gaseous fuels contains less pollutants. Use of hydrogen gives absolutely clean exhaust.

Disadvantages :

Use of alcohols as an alternative fuels have the following disadvantages :

1. Social problems due to prohibition, as it can be consumed as liquor by human beings.
2. The carburettor would need modification, as the stoichiometric Air-fuel ratio with alcohols is quite low (of the order of 10 : 1)
3. The calorific value of alcohol fuels is low as compared to that of diesel or petrol.

The m.e.p. and power output from a given size engine will be low with coal gas and biogas.

The handling and transportation of natural gas is costly.

High compressor power is required to compress it for storage otherwise it will need large storage space.

Hydrogen is highly explosive, and its handling is risky.

What is Advantages and Disadvantages of Alcohol?

Alcohol

Alcohol is an attractive alternative fuel because it can be obtained from a number of sources, both natural and manufactured. Methanol (methyl alcohol) and ethanol (ethyl alcohol) are two kinds of alcohol that seem most promising and have had the most development as engine fuel.

Advantages :

The advantages of alcohol as a fuel are :

1. It is high octane fuel with anti-knock index numbers (octane number on fuel pump) of over 100. High octane numbers result, at least in part, from the high flame speed of alcohol.Engines using high-octane fuel can run more efficiently by using higher compression ratios.
2. It can be obtained from a number of sources, both natural and manufactured.
3. It has high evaporative cooling (hfg) which results in cooler intake process and compression stroke. This raises the volumetric efficiency of the engine and reduces the required work input in the compression stroke.
4. Generally less overall emissions when compared with gasoline.
5. Low sulphur content in the fuel.
6. When burned, it forms more moles of exhaust which gives higher pressure and more power in the expansion stroke.
7. The contamination of matter in alcohols is less dangerous than petrol or diesel because alcohols are less toxic to humans and has a recognizable taste.

Disadvantages :

1. Low energy content of the fuel (Almost twice as much alcohol as gasoline must be burned to give the same energy input to the engine).
2. The exhaust contains more aldehydes. If as much alcohol fuel was consumed as gasoline, aldehyde emissions would be a serious exhaust pollutions problem.
3. As compared to gasoline, alcohol is much more corrosive on copper, brass, aluminium, rubber and many plastics. This puts some restriction on the design and manufacturing of engines to be used with this fuel. Methanol is very corrosive on metals.
4. In general, the ignition characteristic are poor.
5. Vapour lock in fuel delivery system.
6. Owing to low vapour pressure and evaporation, the cold weathering starting characteristics are poor.
7. Due to low vapour pressure, there is a danger of storage tank flammability. Air can leak into storage tanks and create a combustible mixture.
8. Alcohols have almost invisible flames, which is considered dangerous when handling fuel. Again, a small amount of gasoline remove this danger.
9. Low flame temperatures generate less NOx, but the resulting lower exhaust temperatures take longer to heat the catalytic converter to an efficient operating temperature.
10. When refuelling an automobile, headaches and dizziness have been experienced (due to the strong odour of alcohol).

What is advantage And Disadvantage of Methanol ?

Advantages of methanol :

1. Owing to its excellent anti-knock characteristics, it is much suitable for S.I. engines.
2. Methanol use maintains good air quality (Methanol emits less amount of CO2 and other polluting gases as compared to gasoline fueled vehicles).
3. Tertiary butial alcohol is used as an octane improving agent.
4. One percent methanol in petrol is used to prevent freezing of fuel in winter.
5. Iso-propyl alcohol is used as anti-icing agent in carburettor.
6. Addition of methanol causes methanol gasoline blend to evaporate at much faster rate than pure gasoline below its boiling point.