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

為什麼我們不單獨使用太陽能電力? - 亞力山卓．喬治．查拉朗畢德

譯者: Wei-Jung Liu 審譯者: Becky Ma

We have some good reasons to completely

我們有非常充分的理由

switch over to solar power.

完全的使用太陽能。

It's cheaper in many cases,

從各方面來看它比較便宜，

and definitely more sustainable

並且毫無疑問的，

than our dependance on traditional power plants

比起其它我們所依賴的 傳統發電廠，例如煤炭，

that use resources like coal,

更加永續發展，

which will eventually run out.

因為煤炭終究會耗盡。

So why don't we replace these

那麼為何我們不以太陽能

traditional plants with solar energy?

取代這些傳統的發電廠呢?

Because there's one factor that makes

因為其中一個原因

solar power very unpredictable:

使得太陽能非常不好預測:

cloud cover.

那就是雲的遮擋。

As the sun's rays move towards Earth,

當太陽光朝著照射地球時，

some get absorbed by the Earth's atmosphere,

有些會被地球的大氣層所吸收，

some are reflected back into outer space,

有些會反射回到外太空，

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

而剩下的才會照射到地球表面。

The ones that aren't deviated

那些沒有被反射回的

are called direct irradiance.

稱做直射。

The ones that are deflected by clouds

而那些因為雲層而偏射的

are called diffuse irradiance.

則稱作散射。

And those rays that first get reflected by a surface,

那些直接被表面反射的太陽光，

like a nearby building,

例如旁邊的高樓大廈，

before reaching the solar energy system

沒能到達太陽能系統的

are called reflected irradiance.

稱做反射。

But before we can examine how clouds

然而在我們能夠觀測雲層如何影響

affect the sun's rays and electricity production,

太陽光及電力的產生之前，

let's see how these solar energy systems work.

我們來看看太陽能系統的工作原理。

First up, we have solar towers.

首先，我們需要有太陽能塔。

These are made up of a central tower

這個高塔

surrounded by a huge field of mirrors

是由一個很大的，豎滿了 很多鏡子的空地所圍繞

that track the sun's path and focus

用來追蹤太陽的軌跡及焦點

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

並且直接照射到塔上固定的一點，

kind of like an eager beachgoer.

就有點像是一個非常熱切的海灘迷一般

The heat generated by these rays

這些光線會產生熱，

is so immense that it can be used to boil water

而產生的熱是非常巨大足以使水沸騰

producing steam that drives a traditional turbine,

並且產生水蒸氣來推動傳統的渦輪機，

which makes electricity.

而發電。

But when we say solar energy systems,

當我們說太陽能系統時，

we're usually talking about photovoltaics,

我們通常是指光伏電池，

or solar panels,

或是太陽能面板，

which are the systems most commonly used

這些也是非常普遍的

to generate solar power.

太陽能系統發電系統。

In solar panels,

在太陽能板裡，

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

從太陽光而來的光子打到面板表面，

and electrons are released

釋放出電子

to get an electric current going.

並且產生電流流動。

Solar panels can use all types of irradiance,

太陽能板可以接受全部的輻射來源，

while solar towers can only use direct irradiance,

而太陽能塔只能接受直射，

and this is where clouds become important

這就是為什麼雲層變得如此重要

because depending on their type and location

因為會非常依賴它們的種類及地點

relative to the sun,

與太陽之間的關係，

they can either increase or decrease

它們可以直接增加或減少

the amount of electricity produced.

電量的產生。

For instance, even a few cumulus clouds

例如，只要有少量的積雲

in front of the sun can reduce

擋在太陽前方就會減少太陽塔中

the electricity production in solar towers

電量的產生甚至幾乎為零

to almost zero because of this dependence on direct rays.

因為它非常倚賴直接照射的光線。

In solar panels, those clouds would decrease

太陽能板方面，這些雲層也會

energy output as well,

減少能量的輸出沒錯，

though not as much

只不過沒有這麼多

because solar panels can use all types of irradiance.

因為太陽能板可以接收各類型的輻射。

However, all this depends on the clouds exact positioning.

然而，全部都需看雲層實際的位置而定。

Due to reflection, or a particular phenomeon

由於反射，

called Mie scattering,

或是稱做米氏散射的特殊現象，

the sun's rays can actually be focused forward

太陽光其實可以在雲層前端聚焦

by clouds to create a more than 50% increase

產生多於50%的太陽輻射增加量

in the solar irradiance reaching a solar panel.

到太陽能板上。

If this potential increase isn't accounted for,

如果沒有考慮這些潛在的增加，

it could damage the solar panel.

可能會損壞太陽能板。

Why does this matter?

這有什麼重要呢?

Well, you wouldn't want this lesson to stop

我想你應該不希望， 因為雲層通過頂樓的太陽能板

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

使這堂課就這麼結束了。

In solar towers, huge tanks of molten salt or oil

在太陽塔中，有一個大缸子的熔鹽或油

can be used to store any excess heat

可以用來儲存多餘的熱能

and use it when needed,

在需要的時候使用，

so that's how they manage the problem

所以這就是他們如何處理這個問題：

of fluctuating solar irradiance to smooth out

利用照度的起伏不定，

electricity production.

來調整發電量

But in the case of solar panels,

但在太陽能板這方面，

there currently isn't any way to affordably

目前沒有任何可行的方法

store extra energy.

來儲存多餘的能量。

That's where traditional power plants come in

這就是為何傳統發電廠存在

because to correct for any fluctuations

因為可以補足任何

in these solar powered plants,

太陽能電廠的浮動，

extra electricity from traditional sources

傳統發電多餘的電量來源

always needs to be available.

必須保持隨時可以供給的狀態。

But then why aren't these tradtional power plants

但是𤔡何這些傳統發電廠

just used as a backup,

不用來當做備用就好，

instead of us humans depending on them

而人們卻倚賴他們

as our main sources of energy?

成為主要能量來源呢?

Because it's impossible for an employee

因為對在火力發電廠或核能發電廠

at a coal fired or a nuclear plant

的員工而言，

to turn a knob to produce

依據目前天空有多少雲，

more or less electricity depending

來調整應該輸出的電量，

on how many clouds there are in the sky.

是不可能的。

The response time would simply be too slow.

反應時間會太慢。

Instead, to accommodate these fluctuations,

取而代之，為了補足這些浮動，

some extra electricity from traditional power plants

傳統發電廠多餘的電力

is always being produced.

是必須隨時保持供應的。

On clear sky days,

天氣晴朗時，

that extra electricity might be wasted,

多餘的電力或許浪費了，

but when cloudy skies prevail,

但當陰天來臨，

it's what fills the gap.

這就是派上用場的時刻。

This is what we currently depend on

這就是我們現在依賴

for a constant supply of energy.

一個能持續供給的能源。

For this reason, a lot of researchers

就這個理由看來，

are interested in forcasting the motion

有很多的研究者對於 利用衛星雲圖或是拍攝天空的相機

and formation of clouds through satellite images

來預測雲的動態和形成

or cameras that look up at the sky

非常有興趣，

to maximize the energy from solar power plants

因為可以最大化使用太陽能發電廠

and minimize energy waste.

並最小化能源的浪費。

If we could accomplish that,

如果我們可以完成這些，

you'd be able to enjoy this video

你也就可以

powered solely by the sun's rays,

純以太陽能所供的電，來享受這部影片

no matter what the weather,

不論在任何天氣狀況下。

although if the sun is shining,

當然如果太陽很大，

you may be tempted to venture outside

你也可以到戶外

to go and do a different kind of cloud gazing.

欣賞雲層。