How we could make carbon-negative concrete | Tom Schuler

Transcriber: TED Translators Admin Reviewer: Rhonda Jacobs

譯者: Luna Lune 審譯者: Amanda Zhu

Concrete is all around us,

我們身邊到處都是混凝土，

but most of us don't even notice that it's there.

但我們不太會注意到它的存在。

We use concrete to build our roads, buildings, bridges, airports;

我們用混凝土來建造 道路、建築物、橋、機場；

it's everywhere.

混凝土無處不在。

水是唯一比混凝土更常用的資源。

The only resource we use more than concrete is water.

And with population growth and urbanization,

隨著人口增長和都市化，

we're going to need concrete more than ever.

我們比過去更需要混凝土，

But there's a problem.

但是問題來了。

混凝土需要水泥來黏合。

Cement's the glue that holds concrete together.

And to make cement,

製造水泥的方法

you burn limestone with other ingredients in a kiln at very high temperatures.

是將石灰石和其他材料 在窯內以高溫燒製，

One of the byproducts of that process is carbon dioxide, or CO2.

製程中的副產品之一就是二氧化碳。

For every ton of cement that's manufactured,

每製造一噸水泥，

almost a ton of CO2 is emitted into the atmosphere.

就會有近一噸的二氧化碳 釋放到大氣中。

As a result,

因此，

水泥產業成了第二大 二氧化碳的工業排放源，

the cement industry is the second-largest industrial emitter of CO2,

responsible for almost eight percent of total global emissions.

約佔全球二氧化碳排放量的 8%。

If we're going to solve global warming,

要解決全球暖化問題，

innovation in both cement production and carbon utilization

我們就必須在水泥製造和碳利用方面

is absolutely necessary.

有所創新。

Now, to make concrete, you mix cement with stone, sand, and other ingredients,

混凝土的製造是將水泥 與石頭、沙子和其他材料混合，

throw in a bunch of water, and then wait for it to harden or cure.

再加入大量的水，然後等它凝固。

With precast products like pavers and blocks,

要製造地磚或空心磚 這類的預鑄水泥產品，

you might shoot steam into the curing chamber

可能需要將蒸汽噴進養護室裡，

to try to accelerate the curing process.

以加快混凝土凝固。

For buildings, roads, and bridges,

建築物、道路和橋樑的建造

we pour what's called ready-mix concrete into a mold on the job site

是在工地將所謂的預拌混凝土 倒入搭造的模板之間，

and wait for it to cure over time.

然後等待它凝固。

Now, for over 50 years, scientists believed

50 多年來，科學家始終相信，

that if they cured concrete with CO2 instead of water,

如果用二氧化碳代替水 來使混凝土凝固，

這樣的混凝土會更耐用，

it would be more durable,

but they were hamstrung by Portland cement's chemistry.

傳統波特蘭水泥的化學反應 使這個方法不可行。

You see, it likes to react with both water and CO2,

水和二氧化碳都很容易 與石灰產生化學反應，

and those conflicting chemistries just don't make for very good concrete.

這種化學拮抗作用， 讓混凝土品質不太好。

So we came up with a new cement chemistry.

於是我們設計了新的水泥化學反應。

We use the same equipment and raw materials,

我們使用相同的設備和原料，

but we use less limestone,

但減少石灰石的用量，

and we fire the kiln at a lower temperature,

並降低窯內的燒製溫度，

resulting in up to a 30 percent reduction in CO2 emissions.

結果二氧化碳的排放量減少了 30%。

Our cement doesn't react with water.

我們的水泥不會與水反應。

We cure our concrete with CO2,

我們用二氧化碳固化這種混凝土，

and we get that CO2 by capturing waste gas

而這些二氧化碳的來源是 製氨廠或乙醇廠等工業

from industrial facilities like ammonia plants or ethanol plants

所排放的廢氣，

that otherwise would've been released into the atmosphere.

這些廢氣因而不會排放到大氣中。

During curing, the chemical reaction with our cement breaks apart the CO2,

在固化期間，這種水泥化學反應 會分解二氧化碳，

capturing the carbon to make limestone,

分解後產生的碳會製造出更多石灰石，

and that limestone's used to bind the concrete together.

石灰石進而黏合混凝土。

Now, if a bridge made out of our concrete were ever demolished,

如果使用這種混凝土所造的橋被摧毀，

there's no fear of the CO2 being emitted because it doesn't exist any longer.

也不用擔心它會釋放二氧化碳， 因為二氧化碳早就不見蹤影了。

When you combine the emissions reduction during cement production

這種水泥製程中減少的碳排放

with the CO2 consumption during concrete curing,

加上混凝土固化過程中 消耗的二氧化碳，

we reduce cement's carbon footprint by up to 70 percent.

使水泥的碳足跡最多可降低 70%。

And because we don't consume water, we also save trillions of liters of water.

而且這個過程不用水， 所以還能節省上兆公升的水。

Now, convincing a 2,000-year-old industry

不過，混凝土產業已有 2000 年歷史，

that hasn't evolved much over the last 200 years,

而且在過去 200 年裡沒有太大變化，

is not easy;

要說服他們並不容易，

but there are lots of new and existing industry players

幸而目前有許多產業內的新舊企業

that are attacking that challenge.

正在努力迎接這項挑戰。

Our strategy is to ease adoption

我們的策略是尋找 超越永續性的解決方案

by seeking solutions that go beyond just sustainability.

來簡化這項轉型。

We use the same processes, raw material, and equipment

我們採用傳統水泥的 製程、原料和設備，

that's used to make traditional concrete,

but our new cement makes concrete cured with CO2

我們的新型水泥 使用二氧化碳進行固化，

that is stronger, more durable, lighter in color,

製成的混凝土更堅固耐用， 顏色也更淡，

and it cures in 24 hours instead of 28 days.

而且在 24 小時內凝固， 不用等 28 天。

Our new technology for ready-mix

我們製作預拌混凝土的新技術

is in testing and infrastructure applications,

尚在基礎設施應用的測試階段，

and we've pushed our research even further

而且我們推動了進一步研究，

to develop a concrete that may become a carbon sink.

希望能開發出可以用作碳匯的混凝土。

That means that we will consume more CO2 than is emitted during cement production.

這意味著，我們在水泥製程中 消耗的二氧化碳會比排放的更多。

Since we can't use CO2 gas at a construction site,

由於我們無法在建築工地 使用氣態二氧化碳，

we knew we had to deliver it to our concrete

所以必須將二氧化碳以固態或液態形式

in either a solid or liquid form.

注入混凝土中。

So we've been partnering with companies that are taking waste CO2

我們一直在與一些公司合作，

這些公司把二氧化碳廢氣 用來製造一系列有用的化學物質，

and transforming it into a useful family of chemicals

like oxalic acid or citric acid,

比如草酸或檸檬酸，

the same one you use in orange juice.

跟添加在柳橙汁裡的一樣。

When that acid reacts with our cement,

當這種酸性物質 與我們的水泥產生反應，

we can pack in as much as four times more carbon into the concrete,

我們能將四倍的碳儲存在混凝土中，

making it carbon negative.

使碳排放成為負值。

That means that for a one-kilometer road section, we would consume more CO2

意思就是，建造一公里的路段

所消耗的二氧化碳會比 10 萬棵樹 在一年內吸收的還要多。

than almost a 100,000 trees do during one year.

So thanks to chemistry and waste CO2,

有賴化學反應和二氧化碳廢氣，

we're trying to convert the concrete industry,

我們得以試圖將製造地球上 用量第二大材料的混凝土產業，

the second-most-used material on the planet,

into a carbon sink for the planet.

轉變為地球的碳匯。

Thank you.

謝謝。