Why aren't we only using solar power? - Alexandros George Charalambides

为什么我们不只用太阳能发电? - Alexandros George Charalambides

翻译人员: Yi Hou 校对人员: Qiwen Lu

We have some good reasons to completely

我们有很好的理由完全

switch over to solar power.

换去太阳能发电。

It's cheaper in many cases,

在很多情况下它便宜

and definitely more sustainable

并且肯定更有益于可持续发展

than our dependance on traditional power plants

相比于我们现在的发电厂

that use resources like coal,

它们利用化石资源，比如煤，

which will eventually run out.

但煤总有一天会用完的。

So why don't we replace these

那我们为什么不把

traditional plants with solar energy?

传统的电厂换成太阳能？

Because there's one factor that makes

因为有一个因素

solar power very unpredictable:

使太阳能不可预知：

cloud cover.

云遮。

As the sun's rays move towards Earth,

太阳光向地球射来

some get absorbed by the Earth's atmosphere,

有些被大气层吸收，

some are reflected back into outer space,

有些反射回太空，

but the rest make it to the Earth's surface.

但剩下会到达地球表面。

The ones that aren't deviated

没有偏离的光线

are called direct irradiance.

叫直接辐射。

The ones that are deflected by clouds

被云偏转的光线

are called diffuse irradiance.

叫辐射扩散。

And those rays that first get reflected by a surface,

首先被一个平面反射的光线，

like a nearby building,

比如一个附近的建筑物，

before reaching the solar energy system

才达到太阳能系统的

are called reflected irradiance.

叫反射辐射。

But before we can examine how clouds

但在我们考查云层怎样

affect the sun's rays and electricity production,

影响太阳线和发电前

let's see how these solar energy systems work.

先看太阳能系统是如何工作的。

First up, we have solar towers.

第一是太阳能塔。

These are made up of a central tower

这是由一个中央塔

surrounded by a huge field of mirrors

被镜场围住

that track the sun's path and focus

跟踪太阳的路径把

only the direct rays onto a single point on the tower,

直射的阳光集中到塔上一点，

kind of like an eager beachgoer.

就像渴望去海滩的人。

The heat generated by these rays

这些光线产出的热量

is so immense that it can be used to boil water

是很强的可以用来烧开水

producing steam that drives a traditional turbine,

用水蒸气来带动涡轮，

which makes electricity.

来产电。

But when we say solar energy systems,

我们这里说的太阳能系统，

we're usually talking about photovoltaics,

我们说的是光伏，

or solar panels,

或太阳能电池板，

which are the systems most commonly used

这是太阳能系统常用

to generate solar power.

来产电的。

In solar panels,

在太阳能电池板里

photons from the sun's rays hit the surface of a panel,

太阳光线里的光子射到电池板上

and electrons are released

放出电子

to get an electric current going.

电子产生电流。

Solar panels can use all types of irradiance,

太阳能电子板可以用多种辐射，

while solar towers can only use direct irradiance,

但太阳能塔只可以用直接辐射，

and this is where clouds become important

这里就是云的重要处

because depending on their type and location

因为云的类型和

relative to the sun,

相对于太阳的位置，

they can either increase or decrease

可以提高或减少

the amount of electricity produced.

产生的电量。

For instance, even a few cumulus clouds

比如，就算有一点积云

in front of the sun can reduce

在太阳前也可以减少

the electricity production in solar towers

太阳塔产的电

to almost zero because of this dependence on direct rays.

甚至于到零，因为它需要直射。

In solar panels, those clouds would decrease

这些云也会减少太阳能板

energy output as well,

输出的能量，

though not as much

但不是那么多

because solar panels can use all types of irradiance.

因为太阳能板可以用多种辐射。

However, all this depends on the clouds exact positioning.

但，这些都依赖在云的精确位置。

Due to reflection, or a particular phenomeon

由于反射，或一种特别现象

called Mie scattering,

叫 Mie scattering

the sun's rays can actually be focused forward

太阳光集中向前放射

by clouds to create a more than 50% increase

因为云的关系可以增加50%

in the solar irradiance reaching a solar panel.

太阳辐照到达太阳能电池板

If this potential increase isn't accounted for,

如果这个提高没有预算到，

it could damage the solar panel.

会把太阳能电池板损坏。

Why does this matter?

这个有什么关系呢？

Well, you wouldn't want this lesson to stop

你不会想要这个课程停下

just because a cloud passed over the panel on your roof.

就因为云从你的房顶上过去。

In solar towers, huge tanks of molten salt or oil

在太阳能塔里，很大罐的熔盐或油

can be used to store any excess heat

用来储藏多余的热量

and use it when needed,

需要的时候可以用的，

so that's how they manage the problem

就这样管理这个

of fluctuating solar irradiance to smooth out

太阳辐照变换的问题

electricity production.

使产电平衡。

But in the case of solar panels,

但太阳能板

there currently isn't any way to affordably

现在还不能

store extra energy.

储藏多余能源。

That's where traditional power plants come in

传统的发电厂在这有用

because to correct for any fluctuations

因为要改正电源在

in these solar powered plants,

太阳能发电厂的变换，

extra electricity from traditional sources

电源从传统的发电厂

always needs to be available.

总是可用到。

But then why aren't these tradtional power plants

为什么这些传统的发电厂

just used as a backup,

只是当备用，

instead of us humans depending on them

而人类不能依靠这些

as our main sources of energy?

为主要的能量来源？

Because it's impossible for an employee

因为工作人员不可能

at a coal fired or a nuclear plant

在煤火或核电厂

to turn a knob to produce

转动旋钮

more or less electricity depending

来产多或少电

on how many clouds there are in the sky.

根据天上的云多还少。

The response time would simply be too slow.

反应的时间会很慢。

Instead, to accommodate these fluctuations,

要适应这样的变幻

some extra electricity from traditional power plants

传统的发电厂会

is always being produced.

多产一些电。

On clear sky days,

天晴时，

that extra electricity might be wasted,

多出的电会浪费，

but when cloudy skies prevail,

但天阴时，

it's what fills the gap.

有用来补。

This is what we currently depend on

我们现在依靠

for a constant supply of energy.

这个来不断能源供应。

For this reason, a lot of researchers

这个原因，很多研究家

are interested in forcasting the motion

有兴测报云的运动

and formation of clouds through satellite images

和形成通过卫星图像

or cameras that look up at the sky

看天空用的相机来

to maximize the energy from solar power plants

最大化太阳能发电个长的电源

and minimize energy waste.

最小化电源浪费。

If we could accomplish that,

如果我们可以完成这个，

you'd be able to enjoy this video

你会看这个视频

powered solely by the sun's rays,

仅用太阳供的电，

no matter what the weather,

不管气候如何，

although if the sun is shining,

但阳光灿烂时，

you may be tempted to venture outside

你会想向外跑

to go and do a different kind of cloud gazing.

去体会不同样的一种望云。