A concrete idea to reduce CO2 emissions | Karen Scrivener

Transcriber: TED Translators Admin Reviewer: Mirjana Čutura

翻译人员: TED Translators Admin 校对人员: Yolanda Zhang

Concrete is the second most used substance on earth after water,

混凝土是地球上仅次于水的 第二大最常用物质，

and for this reason,

因此，它对环境有很大的影响。

it has a significant environmental impact.

If it were a country, it would rank third for emissions after China and USA.

如果混凝土是一个国家，它的排放量 将位列世界第三，仅次于中国和美国。

But in fact, concrete is an intrinsically low-impact material

但实际上，混凝土本质上 是一种相对环保的材料，

with much lower emissions of CO2 and energy per ton

每吨的二氧化碳 和能量的排放量比钢铁，

than other materials like iron and steel, even things like bricks.

甚至砖等其他材料要低得多。

But because of the enormous volumes we use overall,

但是由于我们使用的总量巨大，

it contributes to about eight percent of man-made CO2 emissions.

它造成了大约 8% 的 人为二氧化碳排放。

Concrete is an essential material.

混凝土是一种 必不可少的建筑材料。

We need it to house people,

我们需要混凝土 来为人们提供住房，

to build roads, bridges and dams.

修建道路、桥梁和大坝。

So we can't do without it,

所以我们不能没有它，

but we can significantly reduce its carbon footprint.

但我们可以显著减少它的“碳足迹”。

Concrete is held together by cement.

混凝土由水泥粘合在一起。

And cement we use today, called Portland cement,

我们今天用的水泥，即波特兰水泥，

is made by heating together a combination of limestone and clay

是由石灰石和粘土 在 1450 摄氏度的高温下

at a temperature of 1,450 degrees Celsius.

加热制成的。

But in fact, most of the CO2 emissions

但事实上，大多数的二氧化碳排放

come not from the heating,

并不是来自加热，

but from the breakdown of limestone, which is calcium carbonate,

而是来自石灰石的分解，

into calcium oxide and carbon dioxide, or CO2.

即从碳酸钙分解成 氧化钙和二氧化碳（CO2）。

Now we can't do without this component altogether,

我们非常需要这样的物质，

because nothing else is so efficient at holding stuff together.

因为没有比它们 更有效的粘合剂了。

But we can replace a large proportion of it

但我们可以用碳足迹更小的

with other materials with lighter carbon footprints.

其他材料替代水泥的大部分成分。

Many colleagues are looking for solutions.

我的很多同事都在寻找 相应的解决方案。

And here in Switzerland,

在瑞士，

we have found that clays produce very reactive materials

我们发现粘土在煅烧时会产生

when they're calcined,

非常活跃的物质——

that's to say heated to around 800 degrees Celsius,

只需要加热到 800 摄氏度左右，

significantly lower than the 1,450 needed to produce cement.

大大低于生产水泥 所需的 1450 摄氏度。

But more importantly, there's no CO2 emissions

但更重要的是，石灰石分解

from the decomposition of limestone.

并不会产生二氧化碳。

We then take this calcined clay,

然后我们在煅烧过的粘土中

and we add a bit of limestone --

加入一点石灰石——

but this time not heated, so no CO2 emissions --

但这次没有加热， 所以没有二氧化碳排放——

and some cement,

还有一些水泥，

and this combination of limestone, calcined clay and cement, we call LC3.

这种由石灰石、煅烧过的粘土 和水泥组成的混合物，我们称之为 LC3。

Now this LC3 here

LC3 与波特兰水泥

has the same properties as Portland cement.

具有相同的性质，

It can be produced with the same equipment and processes

可以用相同的设备和工艺生产，

and used in the same way,

并以相同的方式使用，

but has up to 40 percent lower CO2 emissions.

但却可以降低 近 40% 的二氧化碳排放。

And this was demonstrated in this house we built near Jhansi in India,

关于这一点，我们在印度的贾尼斯附近 建造的房子中已经得到了证明，

二氧化碳的排放量减少了 15 吨，

where we could save more than 15 tons of CO2,

which was 30 to 40 percent compared to existing materials.

与现有材料相比， 相当于降低了 30% 到 40%。

So why isn't everybody already using LC3?

那么为什么 LC3 的使用 还没有普及呢？

Well, cement is a local material.

事实上，水泥是一种本地的材料。

The reason Portland cement is so pervasive

波特兰水泥如此普及的原因在于，

is that it's produced from the most abundant materials on Earth

它是由地球上 含量最丰富的材料制成的，

and can be produced in India,

可以在印度、

in the United States, in Ethiopia, almost anywhere.

美国、埃塞俄比亚等 几乎任何地方生产。

And we have to work with people locally

我们必须与当地人合作，

to find the best combination of materials to make LC3.

以找到制作 LC3 的最佳材料组合。

We have already done full-scale trials in India and Cuba.

我们已经在印度和古巴 进行了全规模的试验，

In Colombia, a product based on this technology

在哥伦比亚， 一种基于这种技术的产品

was commercialized a few months ago,

几个月前已经商业化。

and in the Ivory Coast,

在科特迪瓦，

the full-scale plant is being commissioned to calcine clays.

一家全规模的工厂 已受到委托，正在煅烧粘土。

And many of the world's largest cement companies

许多世界上最大的水泥公司

are looking to introduce this in some of their plants soon.

都希望能够尽快 在他们的一些工厂中引入这种技术。

So the possibility to replace Portland cement

因此，用不同的材料

with a different material --

替代波特兰水泥——

but with the same properties, produced in the same processes

这些材料具有相同的性能， 利用相同的工艺生产，

and used in the same way,

以相同的方式使用，

but with much lighter carbon footprint --

但碳足迹要小得多——

is really crucial to confront climate change

这对于应对气候变化至关重要，

because it can be done fast and it can be done on a very large scale

因为这一过程可以 快速、大规模的实现，

with the possibility to eliminate

每年有可能消除

more than 400 million tons of CO2 every year.

4 亿吨以上的二氧化碳排放。

So we can't do without concrete,

所以，虽然我们不能没有混凝土，

but we can do without a significant amount of the emissions it produces.

但我们可以大大减少它的碳排放。

Thank you.

谢谢大家。