2007年VOA标准英语-Sandia Laboratories Develops Promising Solar Te

By Greg Flakus
Albuquerque, New Mexico
25 July 2007
 

Large scale collection of solar power arrays

As the world searches for ways to produce energy without burning fossil fuel, there is increased interest in solar energy. One place associated with solar power experiments is the Sandia National Laboratories near Albuquerque, New Mexico. VOA's Greg Flakus went there to prepare this report.

When many people think of solar energy they picture simple solar panels for heating water or photovoltaic cells that produce small amounts of electricity for a home.

But here at Sandia Labs, researchers look at big projects that are designed to replace large coal and natural gas electrical generating plants.

One of the most promising¹ technologies is the parabolic solar collector that focuses the sun's rays to heat a gas.  It is a simple engine developed nearly 200 years ago by an inventor in Scotland named Robert Stirling.

Bruce Osborn

A company -- Stirling Energy Systems -- developed the parabolic collector with Sandia Labs researchers. Company President and Chief Executive Officer Bruce Osborn explains how it works. "When you heat a gas, it expands to push a piston², to drive a crankshaft, to drive a generator³ and when you cool it, it contracts. So the Stirling engine is a very simple, elegant and efficient system for taking heat and converting it into electrical power."

The heat that drives the engine comes from mirrors that concentrate the sun's energy on one point.

Mirror array controlled by computers

The whole mirror array is controlled by computers that track the sun throughout the day. Osborn hopes this technology will one day reduce the use of fossil fuels, like coal, which currently provides about half of the electricity generated in the United States. "But I think as we start adding energy usage here in the United States and globally, you will see solar become a bigger part of the portfolio⁴."

Osborn's company already has two power plants operating in the southwestern United States, providing electricity generated by the sun. "These two projects are massive, about four billion kilowatt⁵ hours of electricity from these two projects, and it displaces more than four million tons of greenhouse gases."

Another promising solar technology is the parabolic trough. Here a large curved mirror concentrates the sun's energy on a tube, heating the oil inside it.

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Tim Moss

Sandia project manager Tim Moss explains. "We heat the oil up to a maximum temperature of about 400 degrees C (Centigrade). That is sent through heat exchanges to make steam and from then on it is standard power plant operation of steam sent to steam turbines generating electricity."

Researchers here discovered they could improve the efficiency of the device by carefully aligning⁷ its mirror to concentrate more heat on the tube.

Improved efficiency of solar devices makes them more competitive with traditional energy sources.  Troughs are not as efficient as Stirling engines on parabolic solar collectors.

But Tim Moss says the trough has an important advantage. "Since we are using an oil, or fluid, per se, we can store the heat of that fluid overnight, so we can be generating electricity even when the sun is not shining."

While these technologies are already in use in some parts of the world, researchers here hope that improvements will expand the sun's role in creating a clean energy future.

1 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。

2 piston   

n.活塞

参考例句：

• They use a piston engine instead.他们改用活塞发动机。
• The piston moves by steam pressure.活塞在蒸汽压力下运动。

3 generator   

n.发电机，发生器

参考例句：

• All the while the giant generator poured out its power.巨大的发电机一刻不停地发出电力。
• This is an alternating current generator.这是一台交流发电机。

4 portfolio   

n.公事包；文件夹；大臣及部长职位

参考例句：

• He remembered her because she was carrying a large portfolio.他因为她带着一个大公文包而记住了她。
• He resigned his portfolio.他辞去了大臣职务。

5 kilowatt   

n.千瓦

参考例句：

• They pay thirty fen per kilowatt hour.他们每度电付三角钱。
• The watt is a small unit of power so that we use the kilowatt instead.瓦特是小功率的单位，因此我们用千瓦代之。

6 moss   

n.苔，藓，地衣

参考例句：

• Moss grows on a rock.苔藓生在石头上。
• He was found asleep on a pillow of leaves and moss.有人看见他枕着树叶和苔藓睡着了。

7 aligning   

n. (直线)对准 动词align的现在分词形式

参考例句：

• There are signs that the prime minister is aligning himself with the liberals. 有迹象表明首相正在与自由党人结盟。
• ToolTips provide textual hints that assist in drawing lines and aligning objects. 工具提示提供了协助画线和对象对齐的文本提示。 来自About Face 3交互设计精髓