Assess/evaluate Ethanol... (1 Viewer)

[Abtari]

hi guys,

i am having a bit of strife with ideas on ethanol. here are some points of confusion

1) evaluate the success of current usage of ethanol. how should we go about answering this question (supposing it wasa one)

2)assess the potential of ethanol as an alternative fuel and discuss the advantages and disadvantages of its use (its a syllabus dotpt). for this, do we include the ad/disadvantages in our assessment or do we do that separately. i am finding it hard to answer these assess and evaluate questions.

if anyone could help me with how to answer such keyword questions (in the context of these ethanol concepts) i would be most grateful.

thanks a lot.

 

[MuffinMan]

Ethanol is a fuel that readily burns. It is also an easily transportable liquid. It has been used as a ‘petrol extender’ in the past. Petrol containing 10-20% ethanol can be used in ordinary engines without modification.
Ethanol is produced from carbon dioxide, water and sunlight (via glucose)and when it burns it returns to carbon dioxide and water which is reconverted to ethanol


thats all i got sorry

 

[holla back girl]

well for 1) you would mention how atm ethanol as an alternativce fuel is not fully utilised to its full potential, because of teh cost to produce ethanol. fossil fuels are still relatively available and so are cheap. But in the future, as the fossil fuels are deplete, the use of ethanol may become viable.

2) yes you would separate the adv and disadv:
adv:
cleaner than the combustion of fossil fuels becasue it does not produce co since it has an extra o.
it is renewable; made form glucose which has a great supply
it is biodegradable

disadv:

fermentatation to produce ethanol produces smelly wastes
to separate ethanol form the fermentation mixture, an energy sources is required

for distillation; so this energy source has to be a renewable one such as solar energy rather than fossil fuels (pretty ironic if u use fossil fuels)

and engines for cars needs to be modified if ethanol content in fuel is greater than 30% i think...or maybe 10%


hope it helps...do some research...coz the above just came out of my head...i dun trust it...lmao

 

[Illidan]

evaluate basically means the advantages and dissadvantages. To asses, do the advantages and disadvantages, and include whether it is ecomonically and enviromentally viable.

 

[physician]

@ Abtari....

for (2) heres my answer for that dot pt... now i'm not sure were abouts i got the info.. but it could be a combination of HSC online + Maquarie revision guide... Not really sure...

- Ethanol can be used in internal combustion engines if it cam be economically produced from renewable resources or subsidised as a fuel to reduce air pollution.

Advantages: The advantages are: that it burns more effectively and completely than petrol and therefore produces less toxic emissions. Ethanol has a lower ignition temperature than petrol, It has a greater falmmability range than petrol vapour-airmixtures.

Ethanol petrol belnds reduce carbon monoxide emisiions by 25-30% as well as reducing ozone formation.

Disadvantages: The need to modify fuel lines even the engine if the ethanol is more than 10-15% when mixed with petrol. nother disadvantage is the low price of still readily available petroleum. Large tracts of land would need to be allocated to grwoing plants to use in the production of ethanol rather than food....
(I found these disadvantges realtively easy to learn since most are merely simply logic)


Edit: forgot about 1:

as for (1) ur question is part of the following dot pt:

"process information from secondary sources to summarise the use of ethanol as an alternative car fuel, evaluating the success of current usage"

for the part u asked about...

I got these notes off a class mate...

to evaluate the success of its current usage u should specify a certain place were it's being used...

ok...

Brazil is the world's largest producer and exporter of sugar and fuel alcohol. Brazil's first Pro-Alcohol program conceived in the mid 1970's to combat rocketing oil prices, slowed at the end of the 1980's when ethanol dried up. Brazil has manufactured cars with engines that can run on pure ethanol. According to Brazil's agriculture minister Rodrigues:

" It's one of the biggest generations of jobs, a clean environment and an alternative source of energy"

Brisbane is also quite serious about the use of ethanol as an alternative fuel. BP set a four month trial of ethanol belnded pertol in Brisbane, which was extended due to its success.

Peter Macluspie ( or maccuspie.. not sure), fuels marketing and assurance manager for BP said:

" The trial of premium unleaded with ethanol was a great success, sales performance was good, customers were sstisfied and there were no unforseen technical problems"

 

[Abtari]

coolies. thanks for your help everyone. some of the stuff there is really unique and insightful... very hard to find info like that

hollaback girl, i meant do i write the assess bit separately from advantages/disadvantages, not do i write advantages separate from disadvantages lol... i shoulda made it clearer. no probs

thanks again.

 

[taxman]

Make sure if you assess or evaluate something, that you make a conclusion at the end. Not doing this WILL cost you marks.

So for example; Although there are many advantages for the use of ethanol (biomass fuel, whatever the question asks for) as an alternative fuel, at this stage in time it is not economically viable due to the expense in producing ethanol from biomass or ethylene. Research should be conducted into the use of alternative fuels, but due to the relative cheapness and abundance of fossil fuels, widespread use is not viable until cheaper, more efficient methods for ethanol production are discovered.

Not adding a conclusion will see a good 6 mark response only achieve 4 or 5 marks.

 

[Kroi]

man i love ethanol questions, heres probably around what i'd include

adv:
burns cleaner
aids other petrols to burn efficiently
renewable
carbon dioxide neutral

disadv (theres like a zillion, so many things wrong with it XD):
fermentation is extremely expensive relative to fossil fuels
growing all that biomass to be converted requires heaps of arable land and monoculture is really bad for biodiversity
trucking all that biomass around requires lots of fuel
since ethanol acutally yields less energy than octane rich fuels, (most used one), more has to be burnt to yield the same amount
increased mixes in fuels cause "knocking" and can wear out the engine fast. engine modifications are needed if ethanol mix is increased

facts:
mention Brazil how they use like 10 (or 30%, one of them ><) of their fuel is ethanol. HOWEVER, this is not working despite the facts. this is because the farmers MUST BE SUBSIDISED, since the process is so expensive. its not self-paying off like fossil fuels are.

In China, they are building a plant to use their left over rice stalks from the season and turning them into about 50 million litres of ethanol

assessment:
still too slow and expensive
it is doubtful it will be implemented unless the following occurs:
fossil fuels become dangerously low and there is no other alternative.
or a better process is found to produce ethanol in a cheaper and quicker way

hows that?

 

[Dreamerish*~]

For question 1, use the Brazil example. I've always taken it out of Conquering Chemistry but apparently it's inaccurate. No worries though, I'm sure you won't lose marks, seeing as it is a commonly-used textbook.

In the late 20th century Brazil has attempted to replace non-renewable petrol with ethanol. This also solves the problem of expensive petrol imports by growing and manufacturing their own fuel. However, this project was eventually abandoned due to environmental problems concerning storage of fermentation wastes and land clearing (in order to grow the crops). Another issue raised was the debate about growing crops for fuel, not food. Apparently there are still cars in Brazil that run on ethanol today, but the project has more or less failed overall.

From this you can contrive a judgement. No, it has not been successful... blah blah blah.

Question two (and I hate this question with a passion):

Advantages

• Ethanol is fermented from glucose, which can be obtained from suitable wheats and grains. It is therefore a renewable resource.
• Ethanol releases CO₂ and water when burnt. These products pose no major environmental problems.
• Ethanol is said to be greenhouse neutral. This is because the reactants that make glucose are CO₂ and water (photosynthesis) and look! They are the exact products of the combustion of ethanol!
• Up to 20% ethanol can be used in car engines without engine modification.
• No countries would be bombed for oil. (not really serious about this one - although it is an advantage that countries such as Brazil would be able to manufacture their own fuel instead of importing)
• It is possible to use molasses - wastes from sugar cane farms - to make ethanol.

Disadvantages

• Large amounts of land need to be cleared in order to grow the crops that are needed for fermentation.
• When more than 20% ethanol is to be used in cars, the engine needs to be modified.
• The tank also needs to be enlarged because ethanol has a lower kJ/g than petrol, and therefore will burn more quickly.
• It is extremely expensive and difficult to obtain 100% ethanol from solution because this naughty little polar compound dissolves extremely well in water. A lot of energy is put into distillation, kind of cancelling out the "greenhouse neutral" advantage.
• There are smelly fermentation wastes that raise disposal problems.

That's all I can think of for now.

By the way, assess = evaluation + judgement. With a question like this, it is necessary to point out the advantages and disadvantages in order to make a judgement.

A similar question is "assess the need for monitoring and management of the Haber process reaction vessel" - a whole lot of crap need to be said before you make your judgement.

Check the Glossary of Key Words if you're still unsure.

 

[taxman]

For question 1, use the Brazil example. I've always taken it out of Conquering Chemistry but apparently it's inaccurate. No worries though, I'm sure you won't lose marks, seeing as it is a commonly-used textbook.

My old teacher (before he left to pusue a head teacher position...curse him) was an HSC marker and had told us that they marked incorrect information taken from textbooks as incorrect because...that's right, it was incorrect. Apparently there are a lot of textbooks that are inaccurate and unfortunately there are students who lose marks from writing incorrect information taken from popular textbooks like Chemistry Contexts and Conquering Chemistry.

My best advice would be to research anything that is thought to be inaccurate until you are 100% certain that the information you have is correct. The Chemistry course expects further research into the subject for top line answers.

 

[Casmira]

Don't forget to say about ethanol's volatility is both sometimes an advantage (ie. easier to ignite in a car) but also a disadvantage (ie. safety concern), make sure to address it appropriatley to your discussion (if you're trying to put forward of a positive idea of ethanol then lean towards more of its ease to ignite)

another misc advantage is complete combusion allows less carbon soot to be left on spark plugs, i know its minor but hey, have a good shitload of advantages because you will study so many but only remember 3/4 of that


edit: question ...

if they ask explain the reason of ethanol allowing complete combustion is that because its already got OH in it thus requires not as much oxygen?


edit 2: my notes

in my notes this is what i have, maybe already said but you guys can make some use of it; remember to go about answer the question directly, sure we can talk about the magic and wonders of ethanol, but really we are making a judgement on criteria [sucess of current usage], so like in my response, you can talk about different countrys success, i dont think my answers' all that good but Im going to get my teacher to review my entire (20 page per topic) summarised CCB (Chemistry Casmira Book© )

• Process information from secondary sources to;
• Summarise the use of ethanol as an alternative car fuel
• Evaluate the success of current usage
Ethanol has been used all around the world as an alternative to petrochemicals, pparticulary in Canada, USA and Brazil.
In Canada, most of the petrol petrol contains 10% ethanol, the ethanol is derived from corn/wheat, these types of ethanol blends are becoming increasingly popular. USA also has 10% of ethanol blend in its petrol supply derived from corn, research and trials for upto 95% blend of ethanol-petrol blends used in cars, many cars have been modified to handle the high ethanol concentration.

Brazil has a much higher ethanol concentration of upto 30% in petrol blends, most motor cars can support upto 30% ethanol, this has decreased crude oil importation costs in brazil and increased sugar cane production.

Currently ethanol is dearer to produce than petrol, hampering its use. Ethanol carries the problems of requiring large land use, if that problem can be sorted (ie. to efficiently convert cellulose to glucose) then ethanol has a much greater potential to replace petrochemical fuels, but in the meantime, ethanol will not be as widespread due to costs.


[I havent modified it yet to fit around with brazil's situation yet]

here is my notes on the other question

• Assess the potential of ethanol as an alternative fuel
• Discuss the advantage & disadvantages of its use
Ethanol burns more cleanly than petrol, and can replace all petrols (provided engine is modified), or current use as a petrol extender, by mixing 10%-20% with petrol. It’s good potential as a liquid fuel, particular for transport now as fossil fuels supplies are finite and will deplete. Ethanol carries with it advantages, and disadvantages, some advantages include it’s a renewable resources, reduces carbon monoxide emissions, ethanol also burns more efficiently and has an increased molar heat of combustion than that of petrol.

However, the disadvantages of ethanol include the large areas of agricultural land needed to grow suitable crops for fermentation, car engines would require modification to run on pure ethanol, once fossil fuels supply deplete, this would require a large investment to design and manufacture these engines.

 

[tennille]

Assess= state the value of (ie. advantages and disadvantages of it as many have already mentioned).
Advantages: renewable, almost completely combusts, etc
Disadvantages: smelly fermentation waste, a lot of land to grow sugar cane, etc.

I wouldn't stress to much about these dot points. They were in last years HSC exam paper (and were about 7 marks) and the chances are that they won't be in this years exam. But it is still good to know.

 

[meLoncoLLie]

so does ethanol have a high potential as an alternative fuel?

i still can't decide.

 

[Trefoil]

Not relative to things like hydrogen, nuclear, solar, etc.

Unless somebody finds an efficient and cheap way to produce it from cellulose.

So, basically no. But it's not black and white. It'd be good as an extender where sugar cane waste would otherwise be useless, such as in QLD.

 

[tennille]

so does ethanol have a high potential as an alternative fuel?

i still can't decide.

It's not practical due to the "mess" it will make. There will be a lot of land degradation and waste dumped all over the place.

 

[Dreamerish*~]

so does ethanol have a high potential as an alternative fuel?

i still can't decide.

It doesn't matter what your judgement is, as long as you can back it up with evidence.

You can say:

Yes - ethanol does have a high potential as an alternative fuel because:

• Fossil fuels will be used up within the next few decades - exactly how many is debatable, but it is certain that it is a finite resource.
• Ethanol is probably the major alternative fuel available considering environmental, social and economical aspects.
• Ethanol has a few advantages over petrol - list advantages: greenhouse neutral, biodegradable... etc.

OR

No - ethanol does not have high potential as an alternative fuel because:

• List all disadvantages of ethanol - fermentation wastes, distillation costs, etc.
• Give the Brazil example.

Make sure you always back up your argument with sufficient evidence. With evidence, you can take on any point of view.