1 . On paper, hydrogen（H2）looks like a dream fuel. Coal, oil, and natural gas produce carbon dioxide, which warms the earth when burned, Hydrogen produces pure water. Hydrogen packs more energy into less space than a battery（but certainly less than petrol）. Also, empty tanks（燃料箱）can be refilled with hydrogen much faster than refilling empty batteries with electricity.
While in practice, things are trickier. Storing a meaningful amount of hydrogen gas requires pressing it several hundred-fold. Changing it into the liquid form is another option, but it should be cooled to-253C. Both processes require a heavy and strong tank. While a 700 bar tank is acceptable for a city bus or a truck, adapting it for use in small vehicles is very difficult because the pressure during refilling would be too great.
The solution? Powerpaste.
A German team of researchers, led by Marcus Vogt, have come up with an interesting "powerpaste", which can store hydrogen energy at atmospheric pressure, ready for release when needed. It is so named because it comes in tubes and looks like toothpaste（牙膏）, not in its traditional form of gas.
The main ingredient（原料）of the paste is magnesium hydride, a substance that reacts with water to form hydrogen. The escaped hydrogen can then be directed into a fuel cell, where it reacts with oxygen from the air to produce electric power.
Refueling is very simple, as instead of going to a filling station, drivers and riders can simply replace an empty tube with a new one and refill the water tank.
Given that powerpaste only begins to break down at temperatures of around 250℃ it remains safe even when a vehicle stands in the baking sun for hours.
However, we will have to be patient. Just because researchers have succeeded in developing a new fueling way does not mean that we can expect to see such vehicles on the road anytime soon. It will indeed be several years before this concept is turned into reality.
1. As a fuel, what is the advantage of hydrogen over oil?| A．Refilling empty tanks will be more convenient. |
| B．It is less likely to worsen global warming |
| C．More energy can be packed in the same space. |
| D．It will produce pure water for people to drink. |
| A．The practical difficulties to use hydrogen as fuel in small vehicles. |
| B．The detailed processes of adapting a strong tank in small vehicles. |
| C．The differences in fueling between large vehicles and small ones. |
| D．The tricks of building strong tanks in small vehicles. |
| A．inexpensive | B．powerful | C．convenient | D．environment-friendly |
| A．Powerpaste-driven vehicles sometimes move very slowly on the road. |
| B．Practical use of powerpaste-driven vehicles will not come very soon. |
| C．Powerpaste-driven vehicles can only work after being in the sun for hours |
| D．It will be years before the researchers work out the concept of powerpaste. |
