Putting Plants to Work

　　Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts : They've been using sunlight as an energy source for billions of years.

　　Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into1 sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you're a plant, it's difficult and expensive to convert sunlight into storable energy. That's why scientists are taking a closer look at exactly how plants do it.

　　Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo. 2, is working with green algae3. She's trying to trick them into producing hydrogen4 instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently, the hydrogen that they produce could be used to power fuel

　　Cells in cars or to generate electricity,

　　The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthesis, plants normally make sugars or starches. "But under certain conditions, a lot of algae are able to use the sunlight energy not to store starch, but to make hydrogen. " Ghirardi says. For example, algae will produce hydrogen in an air free environment. It's the oxygen in the air that prevents algae from making hydrogen most of the time.

　　Working in an air free environment, however, is difficult. It's not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate from the environment that the algae grow in, they will make hydrogen instead of sugars, even when air is present.

　　Unfortunately, removing the sulfate also makes the algae's cells work very slowly, and not much hydrogen is produced. Still, the researchers see this as a first step in their goal to produce hydrogen efficiently from algae. With more work, they may be able to speed the cells' activity and produce larger quantities of hydrogen.

　　The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to get and to feed, Ghirardi says, and they can grow almost anywhere: "You can grow them in a reactor, in a pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms. "

　　词汇:

　　panel n. 嵌板，发热板，仪器板 miniature adj. 口巧.微型的

　　carbon dioxide 二氧化碳 algae n. 水藻，海藻

　　starch n. 淀粉 sulfate n. 硫酸盐，硫酸酯

　　photosynthesis n. 光合作用

　　注释:

　　1. convert.., into... : 将……转换为……

　　2. Colo. : Colorado，(美国科罗拉多州)的缩写形式

　　3. Green algae: 绿藻

　　4.trick them into producing hydrogen: 想方设法使它们产生氢。trick作为动词，有“欺骗、哄骗”的意思，但是在这里的意思是“设法”或“采取措施”。

　　练习：

　　1. What does the writer say about plants concerning solar energy?

　　A) Plants are 'the real experts in producing solar energy.

　　B) Plants have been used to produce solar energy.

　　C) Plants have been using solar energy for billions of years.

　　D) Plants have been a source of solar energy.

　　2. Why do some scientists study how plants convert sunlight carbon dioxide, and water into sugars and starches?

　　A) Because they want algae to produce sugars and starches.

　　B) Because they want green plants to become a new source of energy.

　　C) Because they want to turn plant sugars to a new form of energy.

　　D) Because they want to make photosynthesis more efficient.

　　3. According to the fifth paragraph, under what conditions are algae able to use solar energy to make hydrogen?

　　A) When there is a lot of oxygen in the air.)

　　B) When there is no oxygen in the air.

　　C) When photosynthesis is taking place.

　　D) When enough starch is stored.

　　4. Researchers have met with difficulties when trying to make algae produce hydrogen efficiently. Which one of the following is one such difficulty?

　　A) It is not possible to remove sulfate from the environment.

　　B) It is not possible to work in an airfree environment to produce hydrogen.

　　C) It is not easy to make sugars instead of hydrogen.

　　D) It is too slow for algae to produce hydrogen when the sulfate is removed.

　　5. What is NOT true of algae?

　　A) They are easy to grow.

　　B) They can be a very good fuel source.

　　C) They are cheap to eat.

　　D) They can be used in many ways.

　　6. Why do some scientists study how plants convert sunlight carbon dioxide and water into sugars and starches?

　　A) Because they want algae to produce sugars and starch.

　　B) Because they want green plants to become a new source of energy.

　　C) Because they want to turn plant sugars to a new form of energy.

　　D) Because they want to make photosynthesis more efficient.

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