The material that could change the world... for a third time

譯者: Lilian Chiu 審譯者: Helen Chang

Thousands of years ago, the Romans invented a material

數千年前，羅馬人發明了一種材料，

that allowed them to build much of their sprawling civilization.

他們四處擴展的文明有很大一部分 就是靠這種材料打造的。

Pliny the Elder praised an imposing sea wall made from the stuff

老普林尼如此讚美用這東西 建造的宏偉防波堤：

as “impregnable to the waves and every day stronger.”

「海浪也無法攻破，每一天 都變得更堅不可摧。」

He was right: much of this construction still stands,

他說的沒錯，

這建物的絕大部分至今仍然屹立，

having survived millennia of battering by environmental forces

撐過足以擊垮現代大樓的環境力量

數千年的猛擊，都沒有倒下。

that would topple modern buildings.

Today, our roads, sidewalks, bridges, and skyscrapers

現今，我們的道路、 人行道、橋樑，和摩天大樓

are made of a similar, though less durable, material called concrete.

都是用類似的材料建造， 但耐久性較差：

混凝土。

There’s three tons of it for every person on Earth.

平均地球上每一個人 就用了三公噸的混凝土。

And over the next 40 years, we’ll use enough of it

在接下來四十年，

我們會用的混凝土量足以 每個月建造一座紐約市。

to build the equivalent of New York City every single month.

Concrete has shaped our skylines,

混凝土形塑了我們的天際線，

but that's not the only way it's changed our world.

但它不只以這種方式 改變我們的世界。

It’s also played a surprisingly large role in rising global temperatures

在過去一百年間， 它也在全球溫度上升中

扮演相當重大的角色，

over the last century,

a trend that has already changed the world,

溫度上升的趨勢已經改變了世界，

and threatens to even more drastically in the coming decades.

在接下來的數十年 還會造成更大的威脅。

To be fair to concrete, basically everything humanity does

要對混凝土公平一點， 基本上，人類所做的每件事，

contributes to the greenhouse gas emissions that cause global warming.

都會導致溫室氣體排放， 進而造成全球暖化。

Most of those emissions come from industrial processes

大部分排放來自工業製程， 我們通常都不會意識到，

we often aren’t aware of, but touch every aspect of our lives.

卻和我們的日常生活息息相關。

Look around your home.

環伺一下你家裡，

Refrigeration— along with other heating and cooling—

冰箱冷藏以及其他加溫和冷卻

makes up about 6% of total emissions.

佔總排放的約 6%。

Agriculture, which produces our food, accounts for 18%.

我們的食物產自農業， 而農業就佔了 18%。

Electricity is responsible for 27%.

有 27% 和電力有關。

Walk outside, and the cars zipping past, planes overhead,

走到室外，呼嘯而過的汽車，

上空飛過的飛機， 載通勤者去工作的火車——

trains ferrying commuters to work—

transportation, including shipping,

交通，包括運輸在內，

contributes 16% of greenhouse gas emissions.

佔溫室氣體排放的 16%。

Even before we use any of these things, making them produces emissions—

在我們開始使用這些東西之前，

製造它們就會造成排放，

a lot of emissions.

大量的排放。

Making materials—

製造材料——

concrete, steel, plastic, glass, aluminum and everything else—

混凝土、鋼、塑膠、玻璃、 鋁，及其他材料——

accounts for 31% of greenhouse gas emissions.

佔溫室氣體排放的 31%。

Concrete alone is responsible for 8% of all carbon emissions worldwide.

光是混凝土，就佔了

全世界碳排放的 8%。

And it’s much more difficult to reduce the emissions from concrete

從混凝土來減少排放量的難度

than from other building materials.

比其他建材要高許多。

The problem is cement, one of the four ingredients in concrete.

問題在於水泥，

混凝土的四種主要成份之一。

It holds the other three ingredients— gravel, sand, and water— together.

它讓其他三種成份——砂礫、 沙子、水——能結合在一起。

Unfortunately, it's impossible to make cement without generating carbon dioxide.

不幸的是，要製造水泥 就一定會產生二氧化碳。

The essential ingredient in cement is calcium oxide, CaO.

水泥中的主要成份是氧化鈣（CaO）。

We get that calcium oxide from limestone,

我們從石灰石取得鈣，

which is mostly made of calcium carbonate: CaCO3.

石灰石主要由碳酸鈣 （CaCO3）構成。

We extract CaO from CaCO3 by heating limestone.

我們將石灰石加熱， 從 CaCO3 粹取 CaO。

What’s left is CO2— carbon dioxide.

剩下的就是二氧化碳（CO2）。

So for every ton of cement we produce, we release one ton of carbon dioxide.

所以，我們每生產一公噸的水泥，

就會釋放一公噸的二氧化碳。

As tricky as this problem is,

雖然這個問題很難搞，

it means concrete could help us change the world a third time:

卻也表示混凝土能協助我們 第三度改變世界，

by eliminating greenhouse gas emissions and stabilizing our climate.

做法是：消除溫室氣體排放

以及穩定氣候。

Right now, there’s no 100% clean concrete,

目前並沒有 100% 乾淨的混凝土，

but there are some great ideas to help us get there.

但有些很棒的點子 能協助我們達成這個目標。

Cement manufacturing also produces greenhouse gas emissions

水泥製造業在燃燒化石燃料 將石灰石加溫時，

by burning fossil fuels to heat the limestone.

也會產生溫室氣體排放。

Heating the limestone with clean electricity or alternative fuels instead

若能用乾淨電力或替代燃料 來將石灰石加溫，

would eliminate those emissions.

可以避免那些排放。

For the carbon dioxide from the limestone itself,

至於來自石灰石本身的二氧化碳，

our best bet is carbon capture:

我們最看好的做法是碳捕集：

specifically, capturing the carbon right where it’s produced,

明確來說，就是在碳產生時 馬上將它捕集起來。

before it enters the atmosphere.

不要讓它進入大氣。

Devices that do this already exist,

已經有裝置可以做到這一點，

but they aren’t widely used because there’s no economic incentive.

卻未被廣泛使用，因為沒有經濟激勵。

Transporting and then storing the captured carbon can be expensive.

運輸和儲存捕集到的碳 可能會很昂貴。

To solve these problems,

為了解決這些問題， 有一家公司找到一種方式

one company has found a way to store captured CO2 permanently

可以永久儲存捕集到的二氧化碳，

in the concrete itself.

儲存在混凝土本身裡面。

Other innovators are tinkering with the fundamental chemistry of concrete.

其他的創新者則在嘗試修改 混凝土的基礎化學性質。

Some are investigating ways to reduce emissions

有些人在研究有沒有可能透過

by decreasing the cement in concrete.

減少混凝土中的水泥來減少排放。

Still others have been working to uncover and replicate

還有其他人在嘗試找出並複製

the secrets of Roman concrete.

羅馬混凝土的秘密。

They found that Pliny’s remark is literally true.

他們發現老普林尼的 評論的確是真的。

The Romans used volcanic ash in their cement.

羅馬人在他們的水泥中 用上了火山灰。

When the ash interacted with seawater, the seawater strengthened it—

當火山灰與海水產生交互作用，

海水會強化它——

making their concrete stronger and more long-lasting than any we use today.

讓他們的混凝土比我們現今用的 任何混凝土都還要堅固、持久。

By adding these findings to an arsenal of modern innovations,

將這些發現和大量的現代創新整合，

hopefully we can replicate their success—

希望我們能複製出他們的成功——

both by making long lasting structures,

不僅是製造出耐久的結構，

and ensuring our descendants can admire them thousands of years from now.

也能確保數千年後我們的後世子孫

仍然能欣賞它們。