The lecturer points out several problems with the use of hydrogen-based fuel-cell engines in support of her claim that substituting them for internal-combustion engines is technologically unfeasible, environmentally unfriendly, and economically unviable.
First, the lecturer states that it is impractical to replace internal-combustion engines with fuel-cell engines because using the latter requires hydrogen in a pure liquid form, which is technologically challenging to both obtain and store. However, the reading argues that because hydrogen can be extracted from many resources including water, fuel cell engines powered by this infinite source of energy are an extremely attractive alternative.
Second, the lecturer refutes the claim in the reading that hydrogen cells are environmentally friendly. She argues that although engines that use hydrogen cells produce less pollution, the manufacturing of hydrogen cells generates large amounts of harmful by-products due to the burning of fossil fuels in the purification process.
Third, although the reading suggests that hydrogen-based engines are more fuel-efficient and thus economically competitive than internal-combustion engines, the professor argues that such an advantage is undermined by the fact that fuel-cell engines are extremely expensive to manufacture because they require the addition of platinum, a very rare and expensive material.