Næsten alle i verden er en del af et samfund, stort eller lille. Og disse samfund har fælles behov. De har brug for lys. varme, klimaanlæg. Mennesker fungerer ikke optimalt, når det er for varmt eller koldt. De har brug for mad der dyrkes, leveres og opbevares sikkert. Der er brug for at affald indsamles og bortskaffes. Folk skal transporteres fra sted til sted hurtigst muligt. Alle disse aktiviteter kræver energi. Energi i form af elektricitet til lys og aircondition. Energi i form af varme. Og kemisk bundet energi i gødning eller brændstof til landbrugsmaskiner og anden transport.
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.
Jeg har arbejdet 10 år hos NASA. I starten, tilbage i år 2000, var jeg meget interesseret i fællesskaber. Men det var denne slags fællesskab, jeg tænkte på ... en månebase. Beboerne vil have de samme behov, som folk på Jorden har, og samtidig unikke begrænsninger. Og vi tænkte over hvordan, vi kunne levere energi til dette unikke fællesskab. Der er ingen kul på Månen. Der er ingen olie. Der er ingen naturgas. Der er ingen atmosfære Heller ingen vind. Og solenergi har ét stort problem: Månen kredser om Jorden en gang om måneden. I to uger er solen væk, og dine solpaneler laver ingen strøm. At forsøge at lagre energi nok til to uger ved hjælp af batterier er ikke en praktisk løsning. Så atomkraft var det eneste valg.
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.
Tilbage i 2000 vidste jeg ikke ret meget om atomkraft, så jeg forsøgte at lære mere. Næsten al den atomkraft vi bruger her på Jorden i dag bruger vand til køling. Der er der visse fordele ved, men også en masse ulemper. Hvis du vil lave elektricitet, skal vandet være meget varmere end det normalt er. Under normale omstændigheder koger vand ved 100 grader Celsius. Det er langt fra varmt nok til effektivt at lave elektricitet. Så vandkølede reaktorer må køre med langt højere tryk end vores atmosfæriske tryk. Visse vandkølede reaktorer kører med over 70 atmosfærers tryk, og andre bliver nødt til at køre med helt op til 150 atm. tryk Der er ingen vej udenom; du bliver simpelthen nødt til det, hvis du vil lave elektricitet med en vandkølet reaktor. Det betyder du må bygge din vandkølede reaktor som en trykkoger med vægge af stål over 20 cm tykke. Hvis det lyder tungt, så har du ret.
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.
Det kan gå grueligt galt hvis der sker et uheld hvor trykket forsvinder i reaktoren. Hvis du har flydende vand der er 300 grader varmt, og du fjerner trykket forbliver det ikke flydende længe; det forvandles til damp. Så vandkølede reaktorer bygges ind i store, tykke betonbygninger kaldet indeslutningsbygninger, hvis formål er at holde på al den damp, der vil vælte ud af reaktoren, hvis du ved et uheld mister trykket. Damp fylder ca. 1000 gange mere end flydende vand, så indeslutningsbygningen ender med at blive enorm i forhold til reaktorens størrelse.
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.
En anden negativ ting når du mister trykket, og vandet forvandles til damp; Hvis du ikke får køling frem til brændstoffet i reaktoren, kan det overophede og smelte. Vore dages reaktorer bruger uranoxid som brændstof. Det er et keramisk materiale med egenskaber i stil med den keramik vi laver kaffekrus og kogegrej af eller de mursten vi bygger ildsteder af. De er kemisk stabile, men ikke gode til at at transportere varme. Hvis du mister trykket, mister du vandet, og så nedsmelter dit brændstof og frigiver radioaktive fissionsprodukter.
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.
At lave atombrændstof i fast form er en kompliceret og dyr proces. Og vi høster mindre end én procent af energien gemt i det, før det må ud af reaktoren. Vandkølede reaktorer har en yderligere udfordring; de skal ligge nær store vandmasser, hvor dampen kan køles ned og blive til vand igen. Ellers kan de ikke lave elektricitet. Der er bare ingen søer eller floder på Månen, så hvis du synes at vandkølede reaktorer ikke rigtigt passer til en månebase, er vi nok ret enige.
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.
(Latter)
(Laughter)
Til mit store held stødte jeg på en anden form for atomkraft, som ikke har alle disse problemer af en simpel årsag: Den er ikke baseret på vandkøling og bruger ikke fast brændstof. Overraskende nok er den baseret på salt.
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.
En dag jeg besøgte en ven på hans kontor bemærkede jeg denne bog på hylden: "Fluid Fuel Reactors" Jeg blev nysgerrig og spurgte om jeg måtte låne den. I den bog lærte jeg om forskningen i USA tilbage i 1950'erne, i en slags reaktor, der ikke var baseret på fast brændstof eller vandkøling. Den havde ingen af den vandkølede reaktors problemer og årsagen var ligetil. Den brugte en blanding af fluoridsalte som brændstof, konkret flourider af lithium, beryllium, uran og thorium. Flouridsalte er yderst kemisk stabile. De reagerer ikke med luft eller vand. De skal varmes op til omkring 400 grader Celsius før de smelter. Men det er faktisk perfekt til at lave strøm med en atomreaktor.
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.
Det bedste ved det hele: de behøver ikke køre med højt tryk. Og det gør en kæmpe forskel. Det betyder at de ikke skal indkapsles i massive stålkonstruktioner, de behøver ikke vand til køling og der er intet i reaktoren der markant kan ændre massefylde, ligesom vand kan. Så reaktorens indeslutningsbygning kan laves langt mindre og tætsluttende. Modsat faste brændstoffer som nedsmelter, hvis du ikke køler dem, så er flydende flouridsalte allerede smeltet ved en langt lavere temperatur. Under normal drift, er der en lille prop her i bunden af reaktorkammeret. Proppen er lavet af et stykke frosset salt som du holder frosset ved at blæse kold gas på ydersiden af røret. Hvis der opstår en nødsituation og du mister al strøm til dit atomkraftværk, så stopper den lille blæser, den frosne prop smelter, og det flydende fluorid- brændstof i reaktoren løber ud af kammeret, gennem røret og ind i en afløbstank. Afløbstanken er designet til at flytte store mængder varme, så saltet køles passivt, mens varmeudviklingen daler over tid. I vandkølede reaktorer skal du typisk sikre dig strøm til kraftværket for at holde vandet i gang og forhindre nedsmeltning som vi så i Japan. Men mister du strømmen til denne reaktor, så lukker den selv ned uden menneskelig indgriben og overgår til en sikker og stabil tilstand.
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.
Det lød ret godt i mine ører og jeg var spændt på potentialet i at bruge en flydende fluorid-reaktor til strøm på månebasen Men så hørte jeg om thorium og historien blev endnu bedre. Thorium er et naturligt forekommende stof, som er fire gange mere udbredt end uran i jordskorpen. Det kan bruges i flydende fluorid thorium-reaktorer til at lave elektrisk energi, varme og andre værdifulde produkter. Dets høje energitæthed gør at du kan holde et livs forbrug af thorium-energi i håndfladen. Thorium er også udbredt på Månen og nemt at finde. Her er et kort over hvor Månens thorium findes. Thorium har en elektromagnetisk signatur, der gør det nemt at finde selv fra et rumskib.
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.
Med energien fra en flydende fluorid thorium-reaktor kunne vi rense og genbruge al luften, vandet og affaldet på månebasen. Faktisk ville det være en nødvendig forudsætning for succes. Vi kunne dyrke livsvigtige afgrøder til at brødføde indbyggerne, selv gennem en to uger lang månenat med strømmen fra reaktoren. Det så ud til at den flydende fluorid thorium-reaktor (LFTR) kunne være den strømkilde der gjorde en selvforsynende månebase til virkelighed.
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.
Men så spurgte jeg mig selv; hvis det var det helt rette for en månebase hvorfor så ikke også på Jorden i fremtidens samfund, selvforsynende og energi-uafhængigt? De selvsamme teknikker til at lave energi og genbruge affald, som kan have stor betydning i forhold til at overleve på Månen, kan også have stor betydning i forhold til at overleve på Jorden. I dag bruger vi fossile brændstoffer, fordi de er nemme at finde og fordi vi kan. Desværre får de visse dele af vores planet til at ligne Månen. Fossile brændstoffer fører os ind i konflikter i ustabile områder af verden og koster penge og liv.
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.
Alt det kunne ændre sig, hvis vi brugte thorium. Forstår I, i en LFTR kunne vi bruge thorium 200 gange mere effektivt end vi bruger uran nu. Og fordi en LFTR er i stand til at frigive næsten al energien i thorium, reduceres affaldsmængden med en faktor flere hundrede i forhold til uran og med flere millioner i forhold til fossilt brændstof. Vi får stadig brug for flydende brændstof til køretøjer og maskiner men vi kunne lave dette brændstof ud af atmosfærens CO2 og vand, næsten som naturen selv gør. Vi kunne lave brint ved at spalte vand og kombineret med kulstof høstet fra atmosfærens CO2, kunne vi lave brændstoffer såsom methanol, ammoniak og dimethylæter, som direkte kan erstatte dieselbaserede brændstoffer. Forestil jer CO2-neutral benzin og diesel bæredygtigt og selvskabt.
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.
Har vi nok thorium? Ja, vi har. I USA er der over 3.200 tons thorium opmagasineret for 50 år siden som ligger begravet i en kløft i Nevada. Hvis dette thorium blev brugt i LFTR'er, så kunne det producere næsten lige så meget energi som USA bruger på 3 år. Og thorium er ikke et sjældent stof. Der er mange områder, såsom dette i Idaho, på størrelse med en fodboldbane, der kan levere thorium nok årligt til at dække verdens behov for energi.
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.
Med flydende fluorid thorium-teknologi kan vi bevæge os væk fra de dyre og besværlige aspekter ved den nuværende vandkølede uran-baserede atomkraft Vi ville ikke behøve de store højtryks-atomreaktorer og de endnu større bygninger de kræver. Vi ville ikke behøve de store ineffektive dampturbiner. Vi ville ikke behøve de mange lange højspændingskabler for thorium er en meget mobil energikilde, som kan placeres tæt på hvor den behøves. En LFTR er en kompakt enhed, meget energieffektiv og sikker, som kan lave al den energi vi behøver døgnet rundt uden hensyntagen til vind og vejr. i 2007 brugte hele verden 5 milliarder tons kul, 31 milliarder tønder olie, 5 billioner kubikmeter naturgas, og 65.000 tons uran til at dække behovet for energi. Med thorium kan vi nøjes med 7.000 tons, som kan udvindes indenfor et enkelt område.
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.
Hvis du synes dette lyder interessant så besøg vores hjemmeside, hvor et voksende, entusiastisk fællesskab af fortalere for thorium arbejder på at fortælle verden hvordan vi kan opnå en ren, sikker og bæredygtig energi-fremtid, baseret på energien i thorium.
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.
Mange tak (Salen klapper)
Thank you very much. (Applause)