Nearly everyone in the world is part of some community, whether large or small. And all of these communities have similar needs. They need light, they need heat they need air-conditioning. People can't function very well when it's too hot or too cold. They need food to be grown or provided, distributed and stored safely. They need waste products to be collected, removed and processed. People in the community need to be able to get from one place to another as quickly as possible. And a supply of energy is the basis for all of these activities. Energy in the form of electricity provides light and air-conditioning. Energy in the form of heat keeps us warm. And energy in chemical form provides fertilizer; it drives farm machinery and transportation energy.
幾乎世界上的每一個人 都是某個社區的一份子, 不論是大社區或小社區。 所有這些社區都有很類似的需求。 他們都需要光, 需要熱, 需要冷氣空調。 在太熱或太冷的情況下, 人無法運作得很好。 他們需要有人種植、提供、 分發和安全儲存食物。 他們需要將廢產品 收集、丟棄,並進行處理。 社區中的人需要 從一個地方到另一個地方, 且越快越好。 上述所有這些活動的基礎 就是能源供應。 能源以電的形式提供了光和冷氣。 能源的熱形式則能幫我們保暖。 能源的化學形式能提供肥料、 驅動農場機械和交通能源。
Now, I spent 10 years working at NASA. In the beginning of my time there in 2000, I was very interested in communities. But this is the kind of community I was thinking of -- a lunar community It had all of the same needs as a community on Earth would have, but it had some very unique constraints. And we had to think about how we would provide energy for this very unique community. There’s no coal on the Moon. There's no petroleum. There’s no natural gas. There's no atmosphere. There’s no wind, either. And solar power had a real problem: the Moon orbits the Earth once a month. For two weeks, the sun goes down, and your solar panels don't make any energy. If you want to try to store enough energy in batteries for two weeks, it just simply isn't practical. So nuclear energy was really the only choice.
我在美國太空總署工作了十年, 2000 年我剛到那裡時, 我對社區非常感興趣。 但我在想的是這種社區—— 月球社區, 它和地球上的社區 有完全一樣的需求, 但它有一些很獨特的限制。 我們必須要思考 如何為這個獨特的社區提供能源。 因為月球上沒有煤, 沒有石油, 也沒有天然氣。 沒有大氣, 也沒有風。 太陽能有一個真正的問題: 月球每個月會繞地球轉一圈。 有兩個星期是沒有太陽的, 你的太陽能板 就不會產生任何能源。 想在電池中儲存 夠兩星期使用的能源, 是很不實際的。 所以,核能真的是唯一的選擇。
Now, back in 2000, I didn't really know too much about nuclear power, so I started trying to learn. Almost all of the nuclear power we use on Earth today uses water as a basic coolant. This has some advantages, but it has a lot of disadvantages. If you want to generate electricity, you have to get the water a lot hotter than you normally can. At normal pressures, water will boil at 100 degrees Celsius. This isn't nearly hot enough to generate electricity effectively. So water-cooled reactors have to run at much higher pressures than atmospheric pressure. Some water-cooled reactors run at over 70 atmospheres of pressure, and others have to run at as much as 150 atmospheres of pressure. There's no getting around this; it's simply what you have to do if you want to generate electricity using a water-cooled reactor. This means you have to build a water-cooled reactor as a pressure vessel, with steel walls over 20 centimeters thick. If that sounds heavy, that's because it is.
在 2000 年時, 我對核能的了解不多, 所以我開始學習。 幾乎我們在地球上所使用的核能 都用水來當作基本的冷卻劑。 這有好處,但也有很多壞處。 如果你想要發電, 你得要把水加溫到 比一般能達到的溫度高很多。 在一般的壓力下, 水的沸點是攝氏一百度。 這不夠熱,無法 有效地產生出電力。 所以,水冷卻的反應爐 必須在比大氣壓力 高出許多的壓力下運作。 有些水冷卻反應爐在超過 七十個大氣壓的壓力下運作, 其他的則要到一百五十個大氣壓。 這點無法避免; 如果你想用水冷卻反應爐來發電, 就一定得這麼做。 這意味著你得要把水冷卻反應爐 打造成一個壓力容器, 其鋼壁厚度要超過二十公分。 如果這聽起來很重, 是因為的確如此。
Things get a lot worse if you have an accident where you lose pressure inside the reactor. If you have liquid water at 300 degrees Celsius and suddenly you depressurize it, it doesn't stay liquid for very long; it flashes into steam. So water-cooled reactors are built inside of big, thick concrete buildings called containment buildings, which are meant to hold all of the steam that would come out of the reactor if you had an accident where you lost pressure. Steam takes up about 1,000 times more volume than liquid water, so the containment building ends up being very large, relative to the size of the reactor.
更糟糕的是發生意外時, 會造成反應爐中的壓力下降。 如果你有攝氏三百度的液態水, 突然間將它們降壓, 它們不會維持液態太久; 會馬上變成蒸汽。 所以,水冷卻反應爐都會建置在 大型厚混凝土的 建築物中,叫圍阻體, 萬一發生意外造成失壓, 它能夠防止反應爐 產生的蒸汽外漏。 蒸汽的體積是液態水的一千倍, 所以,相對於反應爐的大小, 圍阻體要建得非常大。
Another bad thing happens if you lose pressure and your water flashes to steam. If you don't get emergency coolant to the fuel in the reactor, it can overheat and melt. The reactors we have today use uranium oxide as a fuel. It's a ceramic material similar in performance to the ceramics we use to make coffee cups or cookware or the bricks we use to line fireplaces. They're chemically stable, but they're not very good at transferring heat. If you lose pressure, you lose your water, and soon your fuel will melt down and release the radioactive fission products within it.
萬一失壓且水瞬間變成蒸汽, 還會發生另一件壞事, 如果不將緊急冷卻劑 送到反應爐的燃料那邊, 反應爐可能會過熱熔化。 現今,我們的反應爐 用氧化鈾來當燃料。 那是一種陶瓷材料, 特性很類似我們做咖啡杯 或廚房用具所用的陶瓷, 或是我們用在壁爐上的磚塊。 在化學上,它們是穩定的, 但不太能導熱。 如果反應爐失壓,失去了水, 很快,你的燃料就會熔化, 且釋放出放射性分裂產物。
Making solid nuclear fuel is a complicated and expensive process. And we extract less than one percent of the energy for the nuclear fuel before it can no longer remain in the reactor. Water-cooled reactors have another additional challenge: they need to be near large bodies of water, where the steam they generate can be cooled and condensed. Otherwise, they can't generate electrical power. Now, there's no lakes or rivers on the Moon, so if all of this makes it sound like water-cooled reactors aren't such a good fit for a lunar community, I would tend to agree with you.
製造固態的核燃料 是複雜且昂貴的過程。 在核燃料除役前, 我們對核燃料的 能源利用率還不到 1%。 水冷卻反應爐 還有另一項額外的挑戰: 它們必須要鄰近大型水體, 這樣它們產生出來的蒸汽 才能被冷卻成液體。 要不然,它們就無法產生電力。 在月球上沒有湖泊或河流, 所以,如果你覺得水冷卻反應爐 聽起來並不適用月球社區, 我會傾向同意你的觀點。
(Laughter)
(笑聲)
I had the good fortune to learn about a different form of nuclear power that doesn't have all these problems, for a very simple reason: it's not based on water-cooling, and it doesn't use solid fuel. Surprisingly, it's based on salt.
幸運的是,我學到了 一種不同形式的核能, 它沒有這些問題, 原因很簡單: 它不是以水冷卻為基礎, 且它不用固態燃料。 讓人驚訝的是,它的基礎是鹽。
One day, I was at a friend's office at work, and I noticed this book on the shelf, "Fluid Fuel Reactors." I was interested and asked him if I could borrow it. Inside that book, I learned about research in the United States back in the 1950s, into a kind of reactor that wasn't based on solid fuel or on water-cooling. It didn't have the problems of the water-cooled reactor, and the reason why was pretty neat. It used a mixture of fluoride salts as a nuclear fuel, specifically, the fluorides of lithium, beryllium, uranium and thorium. Fluoride salts are remarkably chemically stable. They do not react with air and water. You have to heat them up to about 400 degrees Celsius to get them to melt. But that's actually perfect for trying to generate power in a nuclear reactor.
有一天,我在朋友的辦公室裡, 我注意到書架上有一本書 《流體燃料反應爐》。 我很感興趣,問他能不能把書借我。 從這本書裡,我得知了 美國在五○年代所做的研究, 研究的是一種 不靠固體燃料的反應爐, 也不用水冷卻。 它沒有水冷卻反應爐的問題, 背後的理由很讚。 它使用氟鹽混合物當核燃料, 明確來說,是氟化鋰、 氟化鈹、氟化鈾和氟化釷。 氟化鹽的化學穩定性非常高。 它們和空氣及水都不會有反應。 將它們加溫到攝氏四百度, 才能讓它們熔化。 但那其實很完美, 很適合在核反應爐當中發電。
Here's the real magic: they don't have to operate at high pressure. And that makes the biggest difference of all. This means they don't have to be in heavy, thick steel pressure vessels, they don't have to use water for coolant and there's nothing in the reactor that's going to make a big change in density, like water. So the containment building around the reactor can be much smaller and close-fitting. Unlike the solid fuels that can melt down if you stop cooling them, these liquid fluoride fuels are already melted, at a much, much lower temperature. In normal operation, you have a little plug here at the bottom of the reactor vessel. This plug is made out of a piece of frozen salt that you've kept frozen by blowing cool gas over the outside of the pipe. If there's an emergency and you lose all the power to your nuclear power plant, the little blower stops blowing, the frozen plug of salt melts, and the liquid fluoride fuel inside the reactor drains out of the vessel, through the line and into another vessel called a drain tank. Inside the drain tank, it's all configured to maximize the transfer of heat, so as to keep the salt passively cooled as its heat load drops over time. In water-cooled reactors, you generally have to provide power to the plant to keep the water circulating and to prevent a meltdown, as we saw in Japan. But in this reactor, if you lose the power to the reactor, it shuts itself down all by itself, without human intervention, and puts itself in a safe and controlled configuration.
真正的魔法是: 它們不需要高壓也能運作。 這一點會造成最大的不同。 這表示它們不需要被放在 又厚又重的壓力鋼容器中, 它們不需要用水當冷卻劑, 反應爐中也沒有像水一樣 密度會發生大改變的東西。 所以反應爐周圍的圍阻體小很多, 幾乎「合身」即可。 不像固態的燃料那樣, 若停止冷卻它們會熔化, 這些液態的氟化燃料已經熔化了, 且熔化的溫度低很多很多。 在一般運作的情況下, 在反應爐容器的底端有個塞子。 這個塞子是用冰凍的鹽做成的, 需不斷用冰冷氣體去吹管子外部, 讓塞子保持冷凍狀態。 如果發生緊急狀況, 核電廠失去所有電力, 吹冷風的裝置停止運作, 冰凍的鹽製塞子會熔化, 反應爐中的液態氟燃料 會流出容器,通過管線, 流入另一個叫做 「排洩槽」的容器。 排洩槽內部已裝配成 將熱傳導最大化, 能在鹽的熱負荷隨時間下降時, 讓鹽可以被動冷卻。 若用水冷卻反應爐, 一般來說,必須給電廠提供電力, 維持水循環流動以防止熔化, 像日本的熔化事件那樣。 但用這個反應爐的情況下, 若失去供應給反應爐的電力, 它完全會靠自己關閉, 不用人類介入, 且會把它自己安置在安全、 受控制的結構中。
Now, this was sounding pretty good to me, and I was excited about the potential of using a liquid fluoride reactor to power a lunar community. But then I learned about thorium, and the story got even better. Thorium is a naturally occurring nuclear fuel that is four times more common in the Earth's crust than uranium. It can be used in liquid fluoride thorium reactors to produce electrical energy, heat and other valuable products. It's so energy-dense that you could hold a lifetime supply of thorium energy in the palm of your hand. Thorium is also common on the Moon and easy to find. Here's an actual map of where the lunar thorium is located. Thorium has an electromagnetic signature that makes it easy to find, even from a spacecraft.
我覺得這聽起來很棒, 想到有可能用液態氟反應爐 來供電給月球上的社區, 我興奮不已。 但,接著,我得知了釷, 故事變得更精采了。 釷是天然產生的核燃料, 在地球的地殼中, 比鈾還要常見四倍。 可以把它用在 液態氟化釷反應爐上, 以產生電、熱, 以及其他珍貴的產物。 它的能源密度非常高, 一個手掌的釷能源 就足以供應你一生的需求。 在月球上,釷很常見,也容易找到。 這是一張標明月球上 釷所在位置的真實地圖。 釷有一種電磁的特徵, 從太空船上都很容易找到它。
With the energy generated from a liquid fluoride thorium reactor, we could recycle all of the air, water and waste products within the lunar community. In fact, doing so would be an absolute requirement for success. We could grow the crops needed to feed the members of the community even during the two-week lunar night, using light and power from the reactor. It seemed like the liquid fluoride thorium reactor, or LFTR, could be the power source that could make a self-sustainable lunar colony a reality.
有了液態氟化釷反應爐產生的能源, 在月球社區內 我們就可以回收 所有的空氣、水和廢棄物。 事實上,若要成功, 就一定得要這麼做。 我們可以種植足夠的作物 供社區成員食用 只需歷時兩週的月夜, 而且使用反應爐產生 的光和電就能做到。 液態氟化釷反應爐(簡稱 LFTR), 這種能源可讓自給自足的 月球殖民夢成真。
But I had a simple question: If it was such a great thing for a community on the Moon, why not a community on the Earth, a community of the future, self-sustaining and energy-independent? The same energy generation and recycling techniques that could have a powerful impact on surviving on the Moon could also have a powerful impact on surviving on the Earth. Right now, we're burning fossil fuels because they're easy to find and because we can. Unfortunately, they're making some parts of our planet look like the Moon. Using fossil fuels entangles us in conflict in unstable regions of the world and costs money and lives.
但我有一個簡單的問題: 如果對於月球社區來說, 它是這麼棒的東西, 為什麼不把它用在 地球上,一個未來社區, 讓它能自給自足、能源沒有依賴性? 對月球上生存產生強大影響的 態源產生和回收技術, 對於地球上的生存也有強大的影響。 現在,我們燃燒化石燃料, 因為很容易取得,且我們懂得運用。 不幸的是,它們正將地球的 某些部分變得像月球一樣。 使用化石燃料, 讓我們捲入世界上 不穩定地區的衝突當中, 付出金錢和人命的代價。
Things could be very different if we were using thorium. You see, in a LFTR, we could use thorium about 200 times more efficiently than we're using uranium now. And because the LFTR is capable of almost completely releasing the energy in thorium, this reduces the waste generated over uranium by factors of hundreds, and by factors of millions over fossil fuels. We're still going to need liquid fuels for vehicles and machinery, but we could generate these liquid fuels from the carbon dioxide in the atmosphere and from water, much like nature does. We could generate hydrogen by splitting water and combining it with carbon harvested from CO2 in the atmosphere, making fuels like methanol, ammonia, and dimethyl ether, which could be a direct replacement for diesel fuels. Imagine carbon-neutral gasoline and diesel, sustainable and self-produced.
如果我們使用釷, 情況可能會非常不同。 在 LFTR 中,我們若使用釷, 和目前使用鈾相比, 使用效率提升兩百倍。 因為 LFTR 能夠 幾乎完全釋放出釷中的能源, 這能將鈾所造成的浪費減少數百倍, 減少化石燃料的浪費數百萬倍。 我們的汽車和機械設備 仍然會需要液態燃料, 但我們可以從大氣 以及水中的二氧化碳 來產生這些液態燃料, 類似大自然的做法。 我們可以將水分解得到氫, 再與從大氣二氧化碳中 提取的碳相結合, 製造出像甲醇、氨、甲醚的燃料, 它們都可以直接取代柴油。 想像一下碳中和的汽油和柴油, 它們既永續又能自行生成。
Do we have enough thorium? Yes, we do. In fact, in the United States, we have over 3,200 metric tons of thorium that was stockpiled 50 years ago and is currently buried in a shallow trench in Nevada. This thorium, if used in LFTRs, could produce almost as much energy as the United States uses in three years. And thorium is not a rare substance, either. There are many sites like this one in Idaho, where an area the size of a football field would produce enough thorium each year to power the entire world.
我們有足夠的釷嗎? 是的,我們有。 事實上,在美國, 我們有超過 3200 公噸的釷, 五十年前就貯存起來的, 目前掩埋在內華達州淺溝中。 如果把這些釷用在 LFTR 中, 能產生的能源足夠美國用三年。 釷也不是稀有的物質。 在愛達荷州還有許多像這樣的地點, 一個足球場面積一年所產出的釷, 就足以供應全世界的電力。
Using liquid fluoride thorium technology, we could move away from expensive and difficult aspects of current water-cooled, solid-fueled uranium nuclear power. We wouldn't need large, high-pressure nuclear reactors and big containment buildings that they go in. We wouldn't need large, low-efficiency steam turbines. We wouldn't need to have as many long-distance power transmission infrastructure, because thorium is a very portable energy source that can be located near to where it is needed. A liquid fluoride thorium reactor would be a compact facility, very energy-efficient and safe, that would produce the energy we need day and night, and without respect to weather conditions. In 2007, we used five billion tons of coal, 31 billion barrels of oil and five trillion cubic meters of natural gas, along with 65,000 tons of uranium to produce the world's energy. With thorium, we could do the same thing with 7,000 tons of thorium that could be mined at a single site.
使用液態氟化釷技術, 我們可以遠離目前昂貴、困難重重、 用水冷卻、採用固態燃料的鈾核能。 我們就不再需要高壓核反應爐, 也不用建造存放它們的大型圍阻體。 我們不再需要大型、 低效率的蒸汽渦輪。 我們就不用這麼多 長距離輸送電力的基礎設備, 因為釷是可攜式的能源來源, 可以放置在需要它的地方附近。 液態氟化釷反應爐會是 一個小型的設施, 有很高的能源效益且很安全, 能夠產生出我們日夜需要的能源, 且不用擔心氣候條件。 2007 年,我們用了 50 億噸的煤、 310 億桶的油、 五兆立方公尺的天然氣、 還有六萬五千噸的鈾, 來產生出世界需要的能源。 若用釷,要達到同樣的效果, 只要在單一地點挖出 七千噸的釷就可以做到。
If all this sounds interesting to you, I invite you to visit our website, where a growing and enthusiastic online community of thorium advocates is working to tell the world about how we can realize a clean, safe and sustainable energy future, based on the energies of thorium.
如果你覺得這些很有意思, 我想請你上我們的網站, 在那裡,一個由提倡釷的人 組成的線上社群正在成長, 透過網站致力於告訴世界, 我們要如何以釷的能源為基礎, 來實現使用乾淨、安全、 永續能源的未來。
Thank you very much. (Applause)
非常謝謝。(掌聲)