A new way to remove CO2 from the atmosphere | Jennifer Wilcox

譯者: Lilian Chiu 審譯者: Yanyan Hong

Four hundred parts per million:

百萬分之四百，

that's the approximate concentration of CO2 in the air today.

那是現今空氣中， 二氧化碳的大約濃度。

What does this even mean?

那到底是什麼意思？

For every 400 molecules of carbon dioxide,

每 400 個二氧化碳的分子，

we have another million molecules of oxygen and nitrogen.

就會有另外 100 萬個氧和氮的分子。

In this room today, there are about 1,800 of us.

現在在這間房間中， 我們大約有 1800 人，

Imagine just one of us was wearing a green shirt,

想像一下，我們當中 只有一人穿綠色上衣，

and you're asked to find that single person.

你被要求去找到那一個人。

That's the challenge we're facing when capturing CO2

那就是現今我們想要直接 捕獲空氣中的二氧化碳時，

directly out of the air.

所遇到的問題。

Sounds pretty easy,

聽起來挺簡單的，

pulling CO2 out of the air.

把二氧化碳從空氣中去除。

It's actually really difficult.

其實真的很困難。

But I'll tell you what is easy:

但告訴各位什麼很容易：

avoiding CO2 emissions to begin with.

一開始就避免排放二氧化碳。

But we're not doing that.

但我們沒有這麼做。

So now what we have to think about is going back;

所以現在我們必須回過頭去；

pulling CO2 back out of the air.

把二氧化碳從空氣中抽出來。

Even though it's difficult, it's actually possible to do this.

即使很困難，還是有可能做到的。

And I'm going to share with you today where this technology is at

今天我要和各位分享的是 這項技術的現況，

and where it just may be heading in the near future.

以及在不遠的將來， 它可能的發展方向。

Now, the earth naturally removes CO2 from the air

地球本身自己就會 把二氧化碳從空氣中除去，

by seawater, soils, plants and even rocks.

透過海水、土壤、植物， 和甚至石頭來做這件事。

And although engineers and scientists are doing the invaluable work

雖然工程師和科學家都投入在

加速這些自然過程的無價工作上，

to accelerate these natural processes,

it simply won't be enough.

就是還不足夠。

The good news is, we have more.

好消息是，我們還有其他方法。

Thanks to human ingenuity, we have the technology today

靠著人類的足智多謀， 我們現在有技術

to remove CO2 out of the air

可以把空氣中的二氧化碳除去，

using a chemically manufactured approach.

利用化學反應的方法。

I like to think of this as a synthetic forest.

我喜歡把它想成是一個合成森林。

There are two basic approaches to growing or building such a forest.

要種出或建造出這樣的森林， 有兩種基本的方式：

One is using CO2-grabbing chemicals dissolved in water.

第一是使用溶解在水中且能夠 抓取二氧化碳的化學物質。

Another is using solid materials with CO2-grabbing chemicals.

第二是使用固態材料， 內含有能抓取二氧化碳的化學物質。

No matter which approach you choose, they basically look the same.

不論你選擇哪一種方法， 基本上它們看起來是一樣的。

So what I'm showing you here is what a system might look like

我接著要給各位看，做這件事的系統

to do just this.

是什麼樣子的。

This is called an air contactor.

這叫做空氣接觸器。

You can see it has to be really, really wide

它必須要非常非常寬，

in order to have a high enough surface area

這樣才能有足夠大的表面積

to process all of the air required,

來處理所有必要的空氣，

because remember,

因為，別忘了，

we're trying to capture just 400 molecules out of a million.

我們試著在一百萬個分子中 捕集四百個分子。

Using the liquid-based approach to do this,

如果要用液體方法來捕集，

you take this high surface area packing material,

你就要用這大表面積的包材，

you fill the contactor with the packing material,

把接觸器用包材裝滿，

you use pumps to distribute liquid across the packing material,

用幫浦將液體分佈至包材的各處，

and you can use fans, as you can see in the front,

還可以用風扇，如圖的前方所示，

to bubble the air through the liquid.

讓空氣通過液體產生泡泡。

The CO2 in the air is separated [by] the liquid

空氣中的二氧化碳和液體分離，

by reacting with the really strong-binding CO2 molecules in solution.

因為它會和溶液中結合力極強的 二氧化碳分子發生作用。

And in order to capture a lot of CO2,

為了要捕集很多二氧化碳，

you have to make this contactor deeper.

這個接觸器必須要做得很深。

But there's an optimization,

但有個最佳化的點，

because the deeper you make that contactor,

因為接觸器越深，

the more energy you're spending on bubbling all that air through.

你就要花更多能源來把空氣打過去。

So air contactors for direct air capture have this unique characteristic design,

所以，直接捕集空氣的空氣接觸器 在設計上有這項獨特的特徵，

where they have this huge surface area, but a relatively thin thickness.

有很大的表面積， 厚度相對就很薄。

And now once you've captured the CO2,

一旦你捕集到了二氧化碳，

you have to be able to recycle that material that you used to capture it,

你就得要回收那些用來捕集它的材料，

over and over again.

一次又一次。

The scale of carbon capture is so enormous

碳捕集工作的規模是很龐大的，

that the capture process must be sustainable,

捕集過程必須要是永續的，

and you can't use a material just once.

材料不能只用一次就丟。

And so recycling the material requires an enormous amount of heat,

而回收那些材料就需要很大量的熱，

because think about it: CO2 is so dilute in the air,

因為，想想看：在空氣中， 二氧化碳會被稀釋，

that material is binding it really strong,

和它結合的材料非常強而有力，

and so you need a lot of heat in order to recycle the material.

因此會需要很大量的熱， 才能回收那些材料。

And to recycle the material with that heat,

如果用那樣的熱來將材料回收，

what happens is that concentrated CO2 that you got from dilute CO2 in the air

會發生的結果是，從空氣中稀釋的 二氧化碳所取得的濃縮二氧化碳

is now released,

現在被釋出了，

and you produce high-purity CO2.

產生了高純度的二氧化碳。

And that's really important,

那很重要，

because high-purity CO2 is easier to liquify,

因為高純度的二氧化碳比較容易液化，

easier to transport, whether it's in a pipeline or a truck,

比較容易運送， 不論是透過管線或是卡車都一樣，

or even easier to use directly,

更容易直接使用，

say, as a fuel or a chemical.

比如，用來當燃料或化學物質。

So I want to talk a little bit more about that energy.

所以，關於那能源， 我想要再多談一點。

The heat required to regenerate or recycle these materials

重新產生或回收這些材料所需要的熱

absolutely dictates the energy and the subsequent cost of doing this.

會直接影響到能源 和做這件事的後續成本。

So I ask a question:

所以我要問一個問題：

How much energy do you think it takes

你們認為要花多少能源

to remove a million tons of CO2 from the air

才能在一年內把空氣中的 100 萬噸

in a given year?

二氧化碳除去？

The answer is: a power plant.

答案是：一座電廠的能量。

It takes a power plant to capture CO2 directly from the air.

需要用一座電廠才能直接 捕集空氣中的二氧化碳。

Depending on which approach you choose,

看你選的方法是哪一種，

the power plant could be on the order of 300 to 500 megawatts.

用的可能是三到五百萬瓦特的電廠。

And you have to be careful about what kind of power plant you choose.

要選哪一種電廠，也要十分謹慎。

If you choose coal,

如果選擇燃煤電廠，

you end up emitting more CO2 than you capture.

最終排放的二氧化碳 可能比捕集到的還多。

Now let's talk about costs.

現在來談談成本。

An energy-intensive version of this technology

這種技術，如果用的是高能源的版本，

could cost you as much as $1,000 a ton

每噸可能要花上 $1,000，

just to capture it.

這只是捕集的成本。

Let's translate that.

讓我把它轉成白話。

If you were to take that very expensive CO2 and convert it to a liquid fuel,

如果你打算要把非常昂貴的 二氧化碳轉換成液態燃料，

that comes out to 50 dollars a gallon.

那麼算起來會是每加侖 $50。

That's way too expensive; it's not feasible.

那實在太貴了，不可行。

So how could we bring these costs down?

我們要如何減低成本？

That's, in part, the work that I do.

我有部分工作在處理這個問題。

There's a company today, a commercial-scale company,

現在有一間公司， 商業規模的公司，

that can do this as low as 600 dollars a ton.

可以壓到每噸 $600 的價格。

There are several other companies that are developing technologies

還有好幾間其他公司在開發技術，

that can do this even cheaper than that.

想要把價格壓到比那更低。

I'm going to talk to you a little bit

我要跟各位談談

about a few of these different companies.

這當中的少數幾間公司。

One is called Carbon Engineering.

其一是「炭工程 （Carbon Engineering）」。

They're based out of Canada.

該公司位在加拿大。

They use a liquid-based approach for separation

他們用液態的方式來做分離，

combined with burning super-abundant, cheap natural gas

再搭配燃燒足夠且便宜的天然氣，

to supply the heat required.

來供應必要的熱。

They have a clever approach

他們有個很聰明的方法，

that allows them to co-capture the CO2 from the air

可以同時捕集空氣中的二氧化碳，

and the CO2 that they generate from burning the natural gas.

以及燃燒天然氣所產生的二氧化碳。

And so by doing this,

透過這麼做，

they offset excess pollution and they reduce costs.

可以抵消掉額外的污染，並減少成本。

Switzerland-based Climeworks and US-based Global Thermostat

瑞士的「氣候工程（Climeworks）」

及美國的「全球恆溫 （Global Thermostat）」公司，

use a different approach.

採用不同的方式。

They use solid materials for capture.

它們用的是固態的捕集法。

Climeworks uses heat from the earth,

氣候工程公司用的是來自地球的熱，

or geothermal,

或地熱，

or even excess steam from other industrial processes

或甚至是工業過程中過量的蒸汽，

to cut down on pollution and costs.

以減少污染以及成本。

Global Thermostat takes a different approach.

全球恆溫公司用的方式不同。

They focus on the heat required

他們把焦點放在必要的熱

and the speed in which it moves through the material

以及熱通過材料的速度，

so that they're able to release and produce that CO2

這麼一來，就可以快速地釋放和產生

at a really fast rate,

那些二氧化碳，

which allows them to have a more compact design

讓他們的設計可以變得更小巧，

and overall cheaper costs.

整體的成本也比較便宜。

And there's more still.

還有更多其他的。

A synthetic forest has a significant advantage over a real forest: size.

和真實的森林比，合成的森林 有一個顯著的優勢：大小。

This next image that I'm showing you is a map of the Amazon rainforest.

我接下來要給各位看的圖， 是亞馬遜雨林的地圖，

The Amazon is capable of capturing 1.6 billion tons of CO2 each year.

亞馬遜每年可以捕集 16 億噸的二氧化碳。

This is the equivalent of roughly 25 percent

這大約等同於美國每年

of our annual emissions in the US.

排放量的 25%。

The land area required for a synthetic forest

換成是合成森林 或專門用來捕集空氣的電廠，

or a manufactured direct air capture plant

若要捕集相同份量的二氧化碳，

to capture the same

所需要用的面積

is 500 times smaller.

小了 500 倍。

In addition, for a synthetic forest,

此外，合成的森林

you don't have to build it on arable land,

並不需要建造在耕地上，

so there's no competition with farmland or food,

不會和農地或食物產生競爭，

and there's also no reason to have to cut down any real trees

也不需要砍伐任何真正的樹木

to do this.

就可以做到。

I want to step back,

我想要先退一步，

and I want to bring up the concept of negative emissions again.

我想要再提一下負排放的概念。

Negative emissions require that the CO2 separated

負排放是要把分離出的二氧化碳

be permanently removed from the atmosphere forever,

永遠從大氣中除去，

which means putting it back underground,

也就是，把它放回到地底，

where it came from in the first place.

因為它最初是從地底來的。

But let's face it, nobody gets paid to do that today --

但要面對現實，現今沒有人 能靠做這種事賺錢——

at least not enough.

至少賺不了多少錢。

So the companies that are developing these technologies

所以，在開發這些技術的公司

are actually interested in taking the CO2

其實是想要把二氧化碳拿來

and making something useful out of it, a marketable product.

做成有用的東西，有市場的產品。

It could be liquid fuels, plastics

可能是液態燃料、塑膠，

or even synthetic gravel.

或甚至合成碎石。

And don't get me wrong -- these carbon markets are great.

別誤會我的意思—— 這些碳市場是很棒的。

But I also don't want you to be disillusioned.

但我也不希望各位的幻想破滅。

These are not large enough to solve our climate crisis,

剛談的這些都還不足以 解決我們的氣候危機，

and so what we need to do is we need to actually think about

我們需要做的是要真正去思考

what it could take.

要花什麼代價。

One thing I'll absolutely say is positive about the carbon markets

對於碳市場， 有一個優點我一定會說，

is that they allow for new capture plants to be built,

那就是，因為它們， 新的捕集廠得以建立起來，

and with every capture plant built,

而每建立一座捕集廠，

we learn more.

我們就會學到更多。

And when we learn more,

當我們學到更多，

we have an opportunity to bring costs down.

我們就有機會把成本降低。

But we also need to be willing to invest

但我們這個全球共同體也得要

as a global society.

願意去投資。

We could have all of the clever thinking and technology in the world,

我們或許有各種聰明的想法和技術，

but it's not going to be enough

但那還不夠讓

in order for this technology to have a significant impact on climate.

這項技術對於氣候產生夠顯著的影響。

We really need regulation,

我們很需要法規，

we need subsidies,

我們需要補助，

taxes on carbon.

碳相關的稅。

There are a few of us that would absolutely be willing to pay more,

很少有人會願意付更多，

but what will be required

但需要做的是，

is for carbon-neutral, carbon-negative paths

要讓碳中和與負碳的途徑

to be affordable for the majority of society

便宜到社會上大部分人都能負擔，

in order to impact climate.

這樣才能對氣候有所影響。

In addition to those kinds of investments,

除了那些投資之外，

we also need investments in research and development.

我們也需要在研究和開發上做投資。

So what might that look like?

所以，看起來會是什麼樣子？

In 1966, the US invested about a half a percent of gross domestic product

1966 年，美國將大約一半的 國內生產總值投資在

in the Apollo program.

阿波羅計畫上。

It got people safely to the moon

該計畫讓人類安全登陸月球，

and back to the earth.

並返回地球。

Half a percent of GDP today is about 100 billion dollars.

當年國內生產總值的一半， 約等於現今的 1000 億。

So knowing that direct air capture

已經知道直接捕集空氣

is one front in our fight against climate change,

是我們對抗氣候變遷之戰的前線，

imagine that we could invest 20 percent, 20 billion dollars.

想像一下，若我們能投資 20%， 即 200 億元，會如何。

Further, let's imagine that we could get the costs down

此外，也想像一下， 我們能把成本降低，

to a 100 dollars a ton.

降到每噸 100 元。

That's going to be hard, but it's part of what makes my job fun.

那會很困難，但這也是讓 我的工作很有趣的原因之一。

And so what does that look like,

所以，200 億元，

20 billion dollars,100 dollars a ton?

每噸 100 元，會是什麼樣子？

That requires us to build 200 synthetic forests,

那會需要建造 200 座合成森林，

each capable of capturing a million tons of CO2 per year.

每一座每年都能夠捕集 100 噸的二氧化碳。

That adds up to about five percent of US annual emissions.

加起來，總共約是 美國每年排放量的 5%。

It doesn't sound like much.

聽起來不很多。

Turns out, it's actually significant.

結果發現，其實是很重大的。

If you look at the emissions associated with long-haul trucking

如果看看長程貨車運輸 以及商業飛機

and commercial aircraft,

相關的排放，

they add up to about five percent.

它們加起來大約是 5%。

Our dependence on liquid fuels makes these emissions

我們對於液態燃料的依賴，

讓這些排放非常難避免。

really difficult to avoid.

So this investment could absolutely be significant.

所以，這項投資絕對是重要的。

Now, what would it take in terms of land area to do this,

要花費多少土地面積，才能做到

200 plants?

200 座捕集廠？

It turns out that they would take up about half the land area of Vancouver.

結果算出來是大約 溫哥華土地面積的一半左右。

That's if they were fueled by natural gas.

前提是要用天然氣來當燃料。

But remember the downside of natural gas -- it also emits CO2.

但別忘了，天然氣也有不利的一面， 它也會排放二氧化碳。

So if you use natural gas to do direct air capture,

所以，如果用天然氣 來直接做空氣捕集，

you only end up capturing about a third of what's intended,

最後只能捕集到 預期量的三分之一左右，

unless you have that clever approach of co-capture

除非你有聰明的同時捕集方法，

that Carbon Engineering does.

就像炭工程公司用的方法。

And so if we had an alternative approach

如果我們有替代的方法，

and used wind or solar to do this,

用風力或太陽能來取代，

the land area would be about 15 times larger,

土地面積會變成約 15 倍大，

looking at the state of New Jersey now.

近似現在的紐澤西。

One of the things that I think about in my work and my research

我在工作和研究時， 會思考的其中一件事情，

is optimizing and figuring out where we should put these plants

是要想出把這些捕集廠 放在哪裡最好，

and think about the local resources available --

並考量可得的當地資源——

whether it's land, water, cheap and clean electricity --

不論是土地、水資源、 便宜且乾淨的電力——

because, for instance, you can use clean electricity

因為，比如，可以用乾淨的電力

to split water to produce hydrogen,

來做水分裂，產生氫，

which is an excellent, carbon-free replacement for natural gas,

氫是很好的天然氣替代品， 不會產生碳，

to supply the heat required.

用來產生需要的熱。

But I want us to reflect a little bit again on negative emissions.

但我希望大家能再次反思負排放。

Negative emissions should not be considered a silver bullet,

負排放不該被視為神奇的解決方案，

but they may help us if we continue to stall

但如果我們在減少全球二氧化碳時

at cutting down on CO2 pollution worldwide.

一直遇到瓶頸， 負排放也許可以幫助我們。

But that's also why we have to be careful.

但也因此，我們得要很小心。

This approach is so alluring that it can even be risky,

這種方法非常誘人， 甚至可能有風險，

as some may cling onto it as some kind of total solution to our climate crisis.

因為有些人可能會太依重它， 把它視為是氣候危機的完全解決方案。

It may tempt people to continue to burn fossil fuels 24 hours a day,

它可能會誘使大家繼續燃燒 化石燃料，一年 365 天，

365 days a year.

一天 24 小時不斷地燒。

I argue that we should not see negative emissions

我主張不要把負排放

as a replacement for stopping pollution,

視為是阻止污染的替代品，

but rather, as an addition to an existing portfolio that includes everything,

而是在既有的方案組合外， 再外加一個無所不包的方案，

from increased energy efficiency

內容從增加能源效能，

to low-energy carbon

到低能源碳，

to improved farming --

到改善農業，

will all collectively get us on a path to net-zero emissions one day.

會一起讓我們有朝一日 能走上淨碳排放為零的路途。

A little bit of self-reflection:

一點點自我反思：

my husband is an emergency physician.

我丈夫是急診室醫生。

And I find myself amazed by the lifesaving work

他和他的同事每天的工作就是

that he and his colleagues do each and every day.

拯救人命，我覺得很了不起。

Yet when I talk to them about my work on carbon capture,

然而，當我和他們談到 我的碳捕集工作時，

I find that they're equally amazed,

他們也同樣覺得很了不起，

and that's because combatting climate change by capturing carbon

那是因為用捕集碳來對抗氣候變遷

isn't just about saving a polar bear

並不只是要拯救北極熊

or a glacier.

或是冰河。

It's about saving human lives.

它也是在拯救人命。

A synthetic forest may not ever be as pretty as a real one,

合成森林可能沒有 真實森林那麼漂亮，

but it could just enable us to preserve not only the Amazon,

但有了它， 我們就不只能保育亞馬遜，

but all of the people

還能保護所有

that we love and cherish,

我們愛與珍惜的人，

as well as all of our future generations

以及我們未來的世代

and modern civilization.

和現代文明。

Thank you.

謝謝。

(Applause)

（掌聲）