Comparing Passage I to Passage II, which of the following questions is not answered in Passage II?
Directions: Answer the question on the basis of what is stated or implied in the twin passage.
Passage – I
Fill 'er up with hydrogen? That’s what some California motorists may be saying soon, as car makers try to ramp up production of zero emission cars to meet state requirements by the year 2003.
Beneath the skin of this ordinary looking prototype sits an electro-chemical reactor: a hand built, astronomically expensive power plant known as a fuel cell. It’s expected to be running ordinary family cars on California’s roads within three years. Rocket scientists have been using fuel cells ever since the United States went to the moon more than 30 years ago. But they're generally too complicated and expensive for much other than a government-sponsored space program.
The California fuel cell partnership says it’s about to change that. Firoz Rasul of Ballard Power Systems says, "A fuel cell, very simply described, is a power generator. It makes electricity. It makes electricity on demand, and it makes it through the combination of hydrogen and oxygen." In this power systems, a hydrogen atom with its one electron, attempts to pass through a fuel cell membrane to unite with an oxygen atom. The membrane allows only the hydrogen proton to pass through, forcing its electron to scurry around the membrane to catch up with the proton on the other side. This creates electricity, water, and heat, but no exhaust emissions. Eight of the world's biggest automobile makers, along with energy companies and fuel cell builders, will work side by side in this Sacramento, California center to learn how to build fuel cell vehicles that work as well as cars with gasoline engines. John Wallace of Ford Motor Company says, "We still have technical challenges getting this extremely complex system to work properly, the way customers expect it to work. There are challenges in using new fuels, and providing the new fuel infrastructure.
And before fuel cell vehicles hit the road, there will have to be a network of hydrogen stations that will allow drivers to fill up with the flammable gas, under 36-hundred pounds of pressure. Manufacturers are confident they can build fuel cell powered vehicles. The questions they hope to answer here are: how reliable can they make them, and can they make them cheap enough for people to buy them.
Passage – II
The basic workings of a fuel cell may not be difficult to illustrate. But building inexpensive, efficient, reliable fuel cells is a far more complicated business.
Scientists and inventors have designed many different types and sizes of fuel cells in the search for greater efficiency, and the technical details of each kind vary. Many of the choices facing fuel cell developers are constrained by the choice of electrolyte. The design of electrodes, for example, and the materials used to make them depend on the electrolyte. Today, the main electrolyte types are alkali, molten carbonate, phosphoric acid, proton exchange membrane (PEM) and solid oxide. The first three are liquid electrolytes; the last two are solids.
The type of fuel also depends on the electrolyte. Some cells need pure hydrogen, and therefore demand extra equipment such as a “reformer” to purify the fuel. Other cells can tolerate some impurities, but might need higher temperatures to run efficiently. Liquid electrolytes circulate in some cells, which requires pumps. The type of electrolyte also dictates a cell’s operating temperature–“molten” carbonate cells run hot, just as the name implies.
Each type of fuel cell has advantages and drawbacks compared to the others, and none is yet cheap and efficient enough to widely replace traditional ways of generating power, such coal-fired, hydroelectric, or even nuclear power plants