TOEFL integrated writing: fuel-cell engines

Both the reading and the lecture talk about ''hydrogen'' as a source of energy for cars. Whereas, the reading passage states that hydrogen might be a good source of energy, the speaker disagrees and claims some reasons to support her position.

In the first place, the reading says that hydrogen might be a good alternative because hydrogen relies on sources that are not easily depleted. On the other hand, the speaker refutes this point and claims that hydrogen might be available from some ordinary sources, but in order to extract the hydrogen from these sources to the liquid state, scientists need a lab. So, an advance lab is needed in order to remove the hydrogen from the water because close to 200 Celsius temp. or more it is requires to keep the hydrogen stable.

Second, the article states that the use of hydrogen as a fuel, might reduce the environmental pollution. On the contrary, the speaker thinks that the hydrogen will not solve the problem of pollution. Rather than solving the problem, hydrogen will increase pollution because in order to get the liquid hydrogen a huge amount of energy is used. So, more gasses are released.

Finally, the Speaker disagrees with the article that states that hydrogen might present an economically alternative to replace combustion engine . The speaker disagrees and thinks that hydrogen's cars require expensive materials such as platinum. This material is very difficult to obtain. Even, some alternatives have been tried to replace platinum, but neither of them have worked successfully.

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it is requires to keep the hydrogen stable.
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an economically alternative to replace combustion engine .
an economical alternative to replace combustion engine .

Attribute Value Ideal
Score: 23 in 30
Category: Good Excellent
No. of Grammatical Errors: 2 2
No. of Spelling Errors: 0 2
No. of Sentences: 13 12
No. of Words: 253 250
No. of Characters: 1256 1200
No. of Different Words: 131 150
Fourth Root of Number of Words: 3.988 4.2
Average Word Length: 4.964 4.6
Word Length SD: 2.473 2.4
No. of Words greater than 5 chars: 103 80
No. of Words greater than 6 chars: 76 60
No. of Words greater than 7 chars: 42 40
No. of Words greater than 8 chars: 19 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 19.462 21.0
Sentence Length SD: 8.706 7.5
Use of Discourse Markers (%): 0.769 0.12
Sentence-Text Coherence: 0.393 0.35
Sentence-Para Coherence: 0.608 0.50
Sentence-Sentence Coherence: 0.176 0.07
Number of Paragraphs: 4 4