TOEFL integrated writing: fuel-cell engines

The professor said it is true that finitude and harm for the environment are the main problems with the internal-combustion engine which relies on petroleum in the form of gasoline or diesel fuel, but the hydrogen-based fuel-cell engine is not an useful solution. She gave her reasons as follow.

First, fuel-cell engines do not use easily available resources. For example, water is not directly usable because of obtaining hydrogen, pure liquid space is needed. Also, it is technically hard to produce and save hydrogen.

Second, not only hydrogen-based fuel cells will not solve the world's pollution problems, but also they create pollution. Producing hydrogen in factories needs lots of energy by burning coal and oil. Therefore, instead of cars, you see pollution from factories.

Third, fuel- cell engines cannot compete with internal-combustion engine economically. In the procedure of producing hydrogen-based fuel cells, some components made of platinum which is very expensive are required. Without the platinum component, hydrogen dose doesn't undergo to chemical reaction to empower the automobile. On the other hand, using cheaper materials has so far been unsuccessful.

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some components made of platinum which is very expensive are required.
Description: two verbs in one sentence.

Sentence: The professor said it is true that finitude and harm for the environment are the main problems with the internal-combustion engine which relies on petroleum in the form of gasoline or diesel fuel, but the hydrogen-based fuel-cell engine is not an useful solution.
Error: finitude Suggestion: No alternate word

flaws:
No. of Words: 181 250
Avg. Sentence Length: 15.083 21.0

Attribute Value Ideal
Score: 23 in 30
Category: Good Excellent
No. of Grammatical Errors: 0 2
No. of Spelling Errors: 1 2
No. of Sentences: 12 12
No. of Words: 181 250
No. of Characters: 974 1200
No. of Different Words: 129 150
Fourth Root of Number of Words: 3.668 4.2
Average Word Length: 5.381 4.6
Word Length SD: 3.128 2.4
No. of Words greater than 5 chars: 74 80
No. of Words greater than 6 chars: 59 60
No. of Words greater than 7 chars: 45 40
No. of Words greater than 8 chars: 30 20
Use of Passive Voice (%): 0 0
Avg. Sentence Length: 15.083 21.0
Sentence Length SD: 9.251 7.5
Use of Discourse Markers (%): 0.667 0.12
Sentence-Text Coherence: 0.334 0.35
Sentence-Para Coherence: 0.573 0.50
Sentence-Sentence Coherence: 0.077 0.07
Number of Paragraphs: 4 4