TOEFL Integrated Writing Practice Test 057Combustion Engine

Automobile manufacturers and governments have been actively searching for a replacement for the internal combustion engine, which currently powers most cars. Among the most promising alternatives is the hydrogen-based fuel-cell engine, which generates electricity from hydrogen to run the vehicle. Fuel-cell engines offer several advantages over internal-combustion engines and are likely to replace them in the near future.

One significant issue with internal-combustion engines is their dependence on petroleum, such as gasoline or diesel. Petroleum is a limited resource, meaning it will eventually run out. In contrast, the hydrogen needed for fuel-cell engines is not easily exhausted. Hydrogen can be extracted from a wide range of abundant sources, including natural gas and even water. The ability to use easily accessible, renewable resources makes fuel-cell engines especially appealing.

Moreover, hydrogen-based fuel cells are attractive because they could help address many global pollution challenges. Burning oil releases carbon dioxide, which harms the environment. In contrast, fuel-cell engines produce only water as a byproduct, making them a much cleaner energy source.

Finally, fuel-cell engines are expected to become economically viable soon, as their operating costs will be lower than those of internal-combustion engines. This is due to their greater fuel efficiency. A fuel-cell-powered vehicle is nearly twice as efficient in fuel use as a car with an internal-combustion engine, meaning the fuel-cell car requires only half the fuel energy to travel the same distance.