Tuesday, 4 February 2014

Alternate fuels

An alternative fuel (aka non-conventional or advanced fuels), is a chemical substances that can be used as a fuel, but is not a conventional fuels.

Why do we need find alternative fuels
  • We need to find alternative fuels since conventional fuels produce excessive amounts of greenhouse gases. This means that earth’s temperature is and will be increasing at such a rate that there will be various negative effects for humanity and Earth in the future. These effects include: 
  • Many species will become extinct, so many biospheres (the global sum of all ecosystems) around the planet will become less biodiverse (the total number of species will decrease).
  • Low lying areas (such as Maldives) will be submerged if we do not decrease our dependency on conventional fuels because if more conventional fuels (especially fossil fuels) are burned, then the polar ice caps will melt and there will be flooding worldwide due to the increase in freshwater in the oceanes. 
  • The seas will become warmer; this will cause more and stronger hurricanes, leading to damage of property, agriculture and loss of lives. So, there will be serious economical and social impacts, for countries rich and poor. 
  • Fresh water supplies will be lost and so prices of many things will increase; this will have a very deep impact on developing or underdeveloped countries. 
  • Furthermore, we need to find alternate fuels because conventional fuels such as fossil fuels are neither sustainable nor renewable. Alternate fuels such as Biofuels. However, biofuels and other current alternative fuels are not yet adequate to meet increasing global demand and so we have to alternative fuels that will meet the demand for fuel effectively and economically in the future,when much of the fossil fuel will be in low availability and prices will be high. 

Biofuels
Definition - fuels that are obtained from living or recently dead organism. Example of biofuels include wood; dried animal droppings (manure); ethanol and biodiesel.
Why are biofuels (nearly) carbon neutral - A fuel is carbon neutral when it has no net release of carbon dioxide to the atmosphere. Biofuels are nearly carbon neutral because they are from living or recently dead organism. This means that when biofuels are being burned, there is no net change in the amount of carbon dioxide in the atmosphere as whatever carbon dioxide the organism have consumed are being release again. However, biofuels are not exactly carbon neutral as carbon dioxide is released when energy is used to transport, cultivate and harvest biofuels.

Pros and cons of using biofuels-

Pros
Cons
They are renewable
A lot of crop and manure is needed to supply enough biofuels.
Will help to reduce the overall amount of carbon dioxide released by human beings so global warming may be brung to a halt
To grow enough crop, we will need to use up a lot of farmland and so there could be a shortage of food
They are nearly carbon neutral
Farmers would have to be educated on how to grow and harvest the crops needed to make biofuels and maybe even how to make them - this will require cooperation and training
They could replace much of the fossil fuels we use
Biofuels such as wood leave a release of a lot of ash when they burn


Hydrogen

How is hydrogen produced for using as a fuel - hydrogen can be generated from natural gas (such as methane). Methane is reacted with water(steam) at high temperatures (700–1100 °C). Here is the reaction:

CH4 + H2O → CO + 3H2

Also, water can be electrolysed so make oxygen and hydrogen, however the majority of hydrogen are generated from natural gas. Here is the equation for electrolysis of water:
2H2O → 2H2+ O2
Pros
Cons
Releases much more megajoule of energy per kg than petrol, methane, kerosene and diesel   
Hydrogen is hard to transport because they have to be stored at high pressures
When burned, it doesn’t release carbon dioxide, only water; so it is a clean fuel.  
Hydrogen is not easily and economically available. Hydrogen filling station will be needed to set up - they are expensive because they will have to store and sell hydrogen

Hydrogen is highly flammable so there could serious accidents

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