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  • Four hundred parts per million:

    譯者: Lilian Chiu 審譯者: Yanyan Hong

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

    百萬分之四百,

  • What does this even mean?

    那是現今空氣中, 二氧化碳的大約濃度。

  • For every 400 molecules of carbon dioxide,

    那到底是什麼意思?

  • we have another million molecules of oxygen and nitrogen.

    每 400 個二氧化碳的分子,

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

    就會有另外 100 萬個氧和氮的分子。

  • Imagine just one of us was wearing a green shirt,

    現在在這間房間中, 我們大約有 1800 人,

  • and you're asked to find that single person.

    想像一下,我們當中 只有一人穿綠色上衣,

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

    你被要求去找到那一個人。

  • directly out of the air.

    那就是現今我們想要直接 捕獲空氣中的二氧化碳時,

  • Sounds pretty easy,

    所遇到的問題。

  • pulling CO2 out of the air.

    聽起來挺簡單的,

  • It's actually really difficult.

    把二氧化碳從空氣中去除。

  • But I'll tell you what is easy:

    其實真的很困難。

  • avoiding CO2 emissions to begin with.

    但告訴各位什麼很容易:

  • But we're not doing that.

    一開始就避免排放二氧化碳。

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

    但我們沒有這麼做。

  • pulling CO2 back out of the air.

    所以現在我們必須回過頭去;

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

    把二氧化碳從空氣中抽出來。

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

    即使很困難,還是有可能做到的。

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

    今天我要和各位分享的是 這項技術的現況,

  • Now, the earth naturally removes CO2 from the air

    以及在不遠的將來, 它可能的發展方向。

  • by seawater, soils, plants and even rocks.

    地球本身自己就會 把二氧化碳從空氣中除去,

  • And although engineers and scientists are doing the invaluable work

    透過海水、土壤、植物, 和甚至石頭來做這件事。

  • to accelerate these natural processes,

    雖然工程師和科學家都投入在

  • it simply won't be enough.

    加速這些自然過程的無價工作上,

  • The good news is, we have more.

    就是還不足夠。

  • Thanks to human ingenuity, we have the technology today

    好消息是,我們還有其他方法。

  • to remove CO2 out of the air

    靠著人類的足智多謀, 我們現在有技術

  • using a chemically manufactured approach.

    可以把空氣中的二氧化碳除去,

  • I like to think of this as a synthetic forest.

    利用化學反應的方法。

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

    我喜歡把它想成是一個合成森林。

  • One is using CO2-grabbing chemicals dissolved in water.

    要種出或建造出這樣的森林, 有兩種基本的方式:

  • Another is using solid materials with CO2-grabbing chemicals.

    第一是使用溶解在水中且能夠 抓取二氧化碳的化學物質。

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

    第二是使用固態材料, 內含有能抓取二氧化碳的化學物質。

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

    不論你選擇哪一種方法, 基本上它們看起來是一樣的。

  • to do just this.

    我接著要給各位看,做這件事的系統

  • This is called an air contactor.

    是什麼樣子的。

  • You can see it has to be really, really wide

    這叫做空氣接觸器。

  • in order to have a high enough surface area

    它必須要非常非常寬,

  • to process all of the air required,

    這樣才能有足夠大的表面積

  • because remember,

    來處理所有必要的空氣,

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

    因為,別忘了,

  • Using the liquid-based approach to do this,

    我們試著在一百萬個分子中 捕集四百個分子。

  • you take this high surface area packing material,

    如果要用液體方法來捕集,

  • you fill the contactor with the packing material,

    你就要用這大表面積的包材,

  • you use pumps to distribute liquid across the packing material,

    把接觸器用包材裝滿,

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

    用幫浦將液體分佈至包材的各處,

  • to bubble the air through the liquid.

    還可以用風扇,如圖的前方所示,

  • The CO2 in the air is separated from the liquid

    讓空氣通過液體產生泡泡。

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

    空氣中的二氧化碳和液體分離,

  • And in order to capture a lot of CO2,

    因為它會和溶液中結合力極強的 二氧化碳分子發生作用。

  • you have to make this contactor deeper.

    為了要捕集很多二氧化碳,

  • But there's an optimization,

    這個接觸器必須要做得很深。

  • because the deeper you make that contactor,

    但有個最佳化的點,

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

    因為接觸器越深,

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

    你就要花更多能源來把空氣打過去。

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

    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,

  • And now once you've captured the CO2,

    有很大的表面積, 厚度相對就很薄。

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

    一旦你捕集到了二氧化碳,

  • over and over again.

    你就得要回收那些用來捕集它的材料,

  • The scale of carbon capture is so enormous

    一次又一次。

  • that the capture process must be sustainable,

    碳捕集工作的規模是很龐大的,

  • and you can't use a material just once.

    捕集過程必須要是永續的,

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

    材料不能只用一次就丟。

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

    而回收那些材料就需要很大量的熱,

  • that material is binding it really strong,

    因為,想想看:在空氣中, 二氧化碳會被稀釋,

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

    和它結合的材料非常強而有力,

  • And to recycle the material with that heat,

    因此會需要很大量的熱, 才能回收那些材料。

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

    如果用那樣的熱來將材料回收,

  • is now released,

    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

  • and you produce high-purity CO2.

    現在被釋出了,

  • And that's really important,

    產生了高純度的二氧化碳。

  • because high-purity CO2 is easier to liquify,

    那很重要,

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

    因為高純度的二氧化碳比較容易液化,

  • or even easier to use directly,

    比較容易運送, 不論是透過管線或是卡車都一樣,

  • say, as a fuel or a chemical.

    更容易直接使用,

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

    比如,用來當燃料或化學物質。

  • The heat required to regenerate or recycle these materials

    所以,關於那能源, 我想要再多談一點。

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

    重新產生或回收這些材料所需要的熱

  • So I ask a question:

    會直接影響到能源 和做這件事的後續成本。

  • How much energy do you think it takes

    所以我要問一個問題:

  • to remove a million tons of CO2 from the air

    你們認為要花多少能源

  • in a given year?

    才能在一年內把空氣中的 100 萬噸

  • The answer is: a power plant.

    二氧化碳除去?

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

    答案是:一座電廠的能量。

  • Depending on which approach you choose,

    需要用一座電廠才能直接 捕集空氣中的二氧化碳。

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

    看你選的方法是哪一種,

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

    用的可能是三到五百萬瓦特的電廠。

  • If you choose coal,

    要選哪一種電廠,也要十分謹慎。

  • you end up emitting more CO2 than you capture.

    如果選擇燃煤電廠,

  • Now let's talk about costs.

    最終排放的二氧化碳 可能比捕集到的還多。

  • An energy-intensive version of this technology

    現在來談談成本。

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

    這種技術,如果用的是高能源的版本,

  • just to capture it.

    每噸可能要花上 $1,000,

  • Let's translate that.

    這只是捕集的成本。

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

    讓我把它轉成白話。

  • that comes out to 50 dollars a gallon.

    如果你打算要把非常昂貴的 二氧化碳轉換成液態燃料,

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

    那麼算起來會是每加侖 $50。

  • So how could we bring these costs down?

    那實在太貴了,不可行。

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

    我們要如何減低成本?

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

    我有部分工作在處理這個問題。

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

    現在有一間公司, 商業規模的公司,

  • There are several other companies that are developing technologies

    可以壓到每噸 $600 的價格。

  • that can do this even cheaper than that.

    還有好幾間其他公司在開發技術,

  • I'm going to talk to you a little bit

    想要把價格壓到比那更低。

  • about a few of these different companies.

    我要跟各位談談

  • One is called Carbon Engineering.

    這當中的少數幾間公司。

  • They're based out of Canada.

    其一是「炭工程 (Carbon Engineering)」。

  • They use a liquid-based approach for separation

    該公司位在加拿大。

  • combined with burning super-abundant, cheap natural gas

    他們用液態的方式來做分離,

  • to supply the heat required.

    再搭配燃燒足夠且便宜的天然氣,

  • They have a clever approach

    來供應必要的熱。

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

    他們有個很聰明的方法,

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

    可以同時捕集空氣中的二氧化碳,

  • And so by doing this,

    以及燃燒天然氣所產生的二氧化碳。

  • they offset excess pollution and they reduce costs.

    透過這麼做,

  • Switzerland-based Climeworks and US-based Global Thermostat

    可以抵消掉額外的污染,並減少成本。

  • use a different approach.

    瑞士的「氣候工程(Climeworks)」

  • They use solid materials for capture.

    及美國的「全球恆溫 (Global Thermostat)」公司,

  • Climeworks uses heat from the earth,

    採用不同的方式。

  • or geothermal,

    它們用的是固態的捕集法。

  • or even excess steam from other industrial processes

    氣候工程公司用的是來自地球的熱,

  • to cut down on pollution and costs.

    或地熱,

  • Global Thermostat takes a different approach.

    或甚至是工業過程中過量的蒸汽,

  • They focus on the heat required

    以減少污染以及成本。

  • and the speed in which it moves through the material

    全球恆溫公司用的方式不同。

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

    他們把焦點放在必要的熱

  • at a really fast rate,

    以及熱通過材料的速度,

  • which allows them to have a more compact design

    這麼一來,就可以快速地釋放和產生

  • and overall cheaper costs.

    那些二氧化碳,

  • And there's more still.

    讓他們的設計可以變得更小巧,

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

    整體的成本也比較便宜。

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

    還有更多其他的。

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

    和真實的森林比,合成的森林 有一個顯著的優勢:大小。

  • This is the equivalent of roughly 25 percent

    我接下來要給各位看的圖, 是亞馬遜雨林的地圖,

  • of our annual emissions in the US.

    亞馬遜每年可以捕集 16 億噸的二氧化碳。

  • The land area required for a synthetic forest

    這大約等同於美國每年

  • or a manufactured direct air capture plant

    排放量的 25%。

  • to capture the same

    換成是合成森林 或專門用來捕集空氣的電廠,

  • is 500 times smaller.

    若要捕集相同份量的二氧化碳,

  • In addition, for a synthetic forest,

    所需要用的面積

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

    小了 500 倍。

  • so there's no competition with farmland or food,

    此外,合成的森林

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

    並不需要建造在耕地上,

  • to do this.

    不會和農地或食物產生競爭,

  • I want to step back,

    也不需要砍伐任何真正的樹木

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

    就可以做到。

  • Negative emissions require that the CO2 separated

    我想要先退一步,

  • be permanently removed from the atmosphere forever,

    我想要再提一下負排放的概念。

  • which means putting it back underground,

    負排放是要把分離出的二氧化碳

  • where it came from in the first place.

    永遠從大氣中除去,

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

    也就是,把它放回到地底,

  • at least not enough.

    因為它最初是從地底來的。

  • So the companies that are developing these technologies

    但要面對現實,現今沒有人 能靠做這種事賺錢——

  • are actually interested in taking the CO2

    至少賺不了多少錢。

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

    所以,在開發這些技術的公司

  • It could be liquid fuels, plastics

    其實是想要把二氧化碳拿來

  • or even synthetic gravel.

    做成有用的東西,有市場的產品。

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

    可能是液態燃料、塑膠,

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

    或甚至合成碎石。

  • These are not large enough to solve our climate crisis,

    別誤會我的意思—— 這些碳市場是很棒的。

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

    但我也不希望各位的幻想破滅。

  • what it could take.

    剛談的這些都還不足以 解決我們的氣候危機,

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

    我們需要做的是要真正去思考

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

    要花什麼代價。

  • and with every capture plant built,

    對於碳市場, 有一個優點我一定會說,

  • we learn more.

    那就是,因為它們, 新的捕集廠得以建立起來,

  • And when we learn more,

    而每建立一座捕集廠,

  • we have an opportunity to bring costs down.

    我們就會學到更多。

  • But we also need to be willing to invest

    當我們學到更多,

  • as a global society.

    我們就有機會把成本降低。

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

    但我們這個全球共同體也得要

  • but it's not going to be enough

    願意去投資。

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

    我們或許有各種聰明的想法和技術,

  • We really need regulation,

    但那還不夠讓

  • we need subsidies,

    這項技術對於氣候產生夠顯著的影響。

  • taxes on carbon.

    我們很需要法規,

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

    我們需要補助,

  • but what will be required

    碳相關的稅。

  • is for carbon-neutral, carbon-negative paths

    很少有人會願意付更多,

  • to be affordable for the majority of society

    但需要做的是,

  • in order to impact climate.

    要讓碳中和與負碳的途徑

  • In addition to those kinds of investments,

    便宜到社會上大部分人都能負擔,

  • we also need investments in research and development.

    這樣才能對氣候有所影響。

  • So what might that look like?

    除了那些投資之外,

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

    我們也需要在研究和開發上做投資。

  • in the Apollo program.

    所以,看起來會是什麼樣子?

  • It got people safely to the moon

    1966 年,美國將大約一半的 國內生產總值投資在

  • and back to the earth.

    阿波羅計畫上。

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

    該計畫讓人類安全登陸月球,

  • So knowing that direct air capture

    並返回地球。

  • is one front in our fight against climate change,

    當年國內生產總值的一半, 約等於現今的 1000 億。

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

    已經知道直接捕集空氣

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

    是我們對抗氣候變遷之戰的前線,

  • to a 100 dollars a ton.

    想像一下,若我們能投資 20%, 即 200 億元,會如何。

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

    此外,也想像一下, 我們能把成本降低,

  • And so what does that look like,

    降到每噸 100 元。

  • 20 billion dollars,100 dollars a ton?

    那會很困難,但這也是讓 我的工作很有趣的原因之一。

  • That requires us to build 200 synthetic forests,

    所以,200 億元,

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

    每噸 100 元,會是什麼樣子?

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

    那會需要建造 200 座合成森林,

  • It doesn't sound like much.

    每一座每年都能夠捕集 100 噸的二氧化碳。

  • Turns out, it's actually significant.

    加起來,總共約是 美國每年排放量的 5%。

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

    聽起來不很多。

  • and commercial aircraft,

    結果發現,其實是很重大的。

  • they add up to about five percent.

    如果看看長程貨車運輸 以及商業飛機

  • Our dependence on liquid fuels makes these emissions

    相關的排放,

  • really difficult to avoid.

    它們加起來大約是 5%。

  • So this investment could absolutely be significant.

    我們對於液態燃料的依賴,

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

    讓這些排放非常難避免。

  • 200 plants?

    所以,這項投資絕對是重要的。

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

    要花費多少土地面積,才能做到

  • That's if they were fueled by natural gas.

    200 座捕集廠?

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

    結果算出來是大約 溫哥華土地面積的一半左右。

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

    前提是要用天然氣來當燃料。

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

    但別忘了,天然氣也有不利的一面, 它也會排放二氧化碳。

  • unless you have that clever approach of co-capture

    所以,如果用天然氣 來直接做空氣捕集,

  • that Carbon Engineering does.

    最後只能捕集到 預期量的三分之一左右,

  • And so if we had an alternative approach

    除非你有聰明的同時捕集方法,

  • and used wind or solar to do this,

    就像炭工程公司用的方法。

  • the land area would be about 15 times larger,

    如果我們有替代的方法,

  • looking at the state of New Jersey now.

    用風力或太陽能來取代,

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

    土地面積會變成約 15 倍大,

  • is optimizing and figuring out where we should put these plants

    近似現在的紐澤西。

  • and think about the local resources available --

    我在工作和研究時, 會思考的其中一件事情,

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

    是要想出把這些捕集廠 放在哪裡最好,

  • because, for instance, you can use clean electricity

    並考量可得的當地資源——

  • to split water to produce hydrogen,

    不論是土地、水資源、 便宜且乾淨的電力——

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

    因為,比如,可以用乾淨的電力

  • to supply the heat required.

    來做水分裂,產生氫,

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

    氫是很好的天然氣替代品, 不會產生碳,

  • Negative emissions should not be considered a silver bullet,

    用來產生需要的熱。

  • but they may help us if we continue to stall

    但我希望大家能再次反思負排放。

  • at cutting down on CO2 pollution worldwide.

    負排放不該被視為神奇的解決方案,

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

    但如果我們在減少全球二氧化碳時

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

    一直遇到瓶頸, 負排放也許可以幫助我們。

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

    但也因此,我們得要很小心。

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

    這種方法非常誘人, 甚至可能有風險,

  • 365 days a year.

    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。

  • I argue that we should not see negative emissions

    它可能會誘使大家繼續燃燒 化石燃料,一年 365 天,

  • as a replacement for stopping pollution,

    一天 24 小時不斷地燒。

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

    我主張不要把負排放

  • from increased energy efficiency

    視為是阻止污染的替代品,

  • to low-energy carbon

    而是在既有的方案組合外, 再外加一個無所不包的方案,