Toefl--- fossil fuels will soon be replaced?

Thanks for reading and commenting it in advance!
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topic: Renewable resources of energy (Sun, wind, water) will soon replace fossils fuels such as gases, oil, and coal. Do you agree or disagree?
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Although renewable resources of energy are elements of the current and future energy strategy, as far as I'm concerned, these new forms of energy cannot soon replace fossil fuels such as gases, oil, and coal.

Firstly, due to the limitation of technology renewable resources are relatively expensive. Researches in renewable energy cost a huge amount of money which developing countries cannot afford. On the other hand, fossil fuels are abundant and inexpensive in many areas. For example, it is estimated that China has the largest deposit of coal in the world and the government does not want to invest too much money on new forms of energy, say expensive solar batteries and wind farms. Thus the plan of renewable resources of energy may face challenges in that not every country can afford the reforming.

Besides, although utility companies claim that renewable energy is environmentally friendly; these new forms of energy may not be as clean and green as we think. Latest studies have shown that these renewable resources of energy are problematic as well and they are very likely to pose lone-term environmental hazards. For example, the dams built for hydroelectricity influence the water flows of the rivers and sometimes cause drought in areas in front of the dams. This damages the habitats of many valuable fish and wading birds. More importantly, the accumulation of heavy metal in the silt on the bottom of the rivers behind the dams is extremely difficult and expensive to clean up; leaving problems for the following generations. Thus renewable resources are not as reliable as we think.

Admittedly contemporarily fossil fuels cause serious environmental conundrums such as acid rain, deduction of ozone layer and global warming; these problems can be solved by improving efficiency of the mechanism and reducing emissions. For example we can use chemicals to desulfurize the emissions from plants and vehicles to avoid acid rain. These improving methods are often cheaper and simpler compared to the high-tech of renewable energy. With these solutions fossil fuels seem more sustainable.

In conclusion as promising as renewable resources of energy sound, there is no way those new forms of energy will replace fossil fuels soon.

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Many of your arguments are cogent. The example of hydroelectric dams is quite good, although this does not demonstrate that this form of energy is not "reliable," only that it comes with its own environmental hazards. The chief problem is that you are confusing "green" (in the sense of non-polluting) with renewable. Fossil fuels can never be sustainable, because they are finite. No matter how technology is used to make them burn more cleanly, burning them depletes a finite supply which will eventually run out.

But this is a TOEFL essay, and so our chief concern must be your English rather than your logic. For the most part, your grammar is good and your punctuation accurate.

Here are a few fixes:
Research in renewable energy costs a huge amount of money, which developing countries cannot afford.

For example, it is estimated that China has the largest deposit of coal in the world, and the government does not want to invest too much money on new forms of energy such as expensive solar batteries and wind farms.

Admittedly,contemporarily fossil fuels cause serious environmental conundrums such as acid rain, depletion of the ozone layer, and global warming; these problems can be mitigated by improving the efficiency of the mechanisms and thereby reducing emissions.

Thank you Simone. I got that example from a listening material in Toefl I used to listen.
I'll be more careful with grammar.

If I change the meaning of the third paragraph to: we can improve efficiency so that fossil fuels may last longer. As long as there is the alternative of cheap fossil fuel, it's unlikely to replace fossil fuels completely.

Will that be more logical?

Yes, that would make more sense.

the format of your essay is good, but i think u should not write" i'm" you should write "i am".

moreover are u sure that fossil fuel is abundant? i dont think so.

Maybe not oil, but coal is abundant.
We cannot use contractions in written English? Never noticed this problem before...