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Controversial Issues (backup)
 

Controversial Issues (backup)

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  • I’d like to start with a demonstration, for this I need a volunteer.Okay, I’d like you to take this bottle, and pour some, but not all, of the liquid into the measuring jug here.Thank you. Now please read out how much liquid you’ve poured out.Here we have 240ml of liquid. Now tell me, how much is left in the bottle?That’s actually very close, but no matter how hard you try, it can only be an estimate.Thanks, please sit down.I’m not just getting you to pour liquids around for nothing. This liquid, although it’s just water and food colouring, represents oil. The jug is all the oil we’ve drilled out of the ground and burnt, and the bottle the earth. We know how much is in the jug, but we can only guess how much is left in the bottle. Since we don’t know how much oil is left, we can’t know how long we’ve got left.And now we’re running out. As easier reserves to extract run dry, we’re being forced to turn to oil in places which are harder to get to. But even these won’t last forever.
  • One of the first people to realise that we were using up finite reserves was a geologist named M. King Hubbert in 1956. This was his original prediction. He said the peak of oil production would occur in around 1995.
  • ...and we now know he was wrong on this count – production is still slowly rising. But you don’t have to be a geologist or an economist to see that we will eventually run out.
  • And it’s happening already, although not on a global scale. Here’s the oil production in Texas over the last 80 years. The numbers don’t really matter here, but does the shape look familiar?
  • So when’s this going to happen? Matthew Simmons, an investment banker involved in oil trading, once said "...peaking is one of these fuzzy events that you only know clearly when you see it through a rear view mirror, and by then an alternate resolution is generally too late.“Although I was talking about oil just then, the same thing is true for all other fossil fuels: coal, oil, gas and any others, like tar sands.
  • So oil is running out, as are other fossil fuels. In 2011, coal and gas together made up 70% of UK electricity supply. Why? Because they’re cheap. Natural gas is one of the cheapest ways to generate power, and coal isn’t far behind.But we can’t keep burning them forever. We urgently need another source of power.
  • How about these? Renewable energy. The wind, the sun and the rivers: clean, abundant power for all. Well, sorry to disappoint you, but they’re far from perfect.
  • On the Yangtze river in China, engineers have been hard at work building this: the Three Gorges Dam. As I speak, the turbines have been in operation less than two years, but are fully functional, supplying twenty-two gigawatts of electricity. That’s about enough to power half of the UK. But the price? How many people’s homes do you think were submerged by the lake formed behind it?Approximately one and a half million. The population of Birmingham is only one point one.
  • Here’s the Yangtze river in 1987
  • And here it is in 2006. All the people who lived under this water have been forced out of their homes. But even more importantly, if the government of China wants a million people to be moved, a million people will be moved: it’s not the same in a democracy.
  • So, hydroelectricity ends up with people’s houses underwater, that’s not exactly going to be popular, even if we had enough potential sites here in the UK. But what about wind turbines? We already have quite a lot, so we know they work, and nobody has to be displaced.But they still make pretty nasty neighbours. A petition to the Department of Energy and Climate Change asking for no more turbines to be built in the UK gathered thirteen thousand seven hundred and sixty-five signatures, with its creator writing...
  • “Locally, they industrialise the landscape, have detrimental health, financial and other effects on peoples lives, destroy wildlife and have a negative impact on tourism”Then somebody had an idea: why not put the turbines...
  • ...in the sea?Alas, there is a catch. It is incredibly expensive to build foundations underwater, and considering how many turbines you need, it gets too costly, very fast. This picture above is the Sheringham Shoal wind farm off the coast of north Norfolk, and its 88 turbines, capable of supplying around 220,000 homes (that, for comparison, is a hundredth of the Three Gorges), cost around one billion pounds to build. That works out at over four thousand pounds per home supplied, and when the average annual energy bill is closer to one thousand, that’s a lot of money to regain.Investment – but little running cost?One-off vs recurrent costs?
  • So dams, while providing lots of power, submerge houses, and wind turbines are expensive and noisy. But what about solar? Not noisy, they don’t need to be in the sea, and they don’t flood houses. But, you guessed it, there’s a catch. Solar generation is expensive. Seriously expensive It’s up there with offshore wind. Also, forget about solar in Britain. There’s a reason most plans for solar generation involve the Sahara desert or Spain...
  • ...this is our British weather
  • So renewable energy, while it promises much, is generally expensive, and has a few other problems too. But we need to do something: we can’t carry on burning prehistoric life forever.
  • Anybody know what this is?Uranium. It’s a dull grey metal, found naturally in the earth’s crust and slightly radioactive. It’s not going to run out any time soon (more on that later) and using it to generate electricity produces no CO2. It’s also the fuel for every commercial nuclear power plant in the world.ATOMS – USE A SCHWA
  • Uranium atoms are large, with an atomic weight of 235-238. This means that the nucleus is unstable, so it will split easily. In a nuclear power plant, the uranium is bombarded with neutrons, causing it to break apart into lighter elements. The energy joining the particles in the nucleus together is huge, and in this reaction it is released mostly as heat. Also released are a few neutrons. These hit other uranium atoms, and the same process happens again – a chain reaction. Left to its own devices, the result would be an explosion – indeed that’s how most nuclear weapons work.To control the reaction, neutron moderators are used. These are substances which absorb neutrons, slowing down or stopping the reactions. Water and graphite are the most common.This vast amount of energy is manifested as heat, which is used to boil water, making steam and driving turbines to generate electricity.
  • What’s your opinion. Are nuclear power plants safe?You’re absolutely right. Accidents can, and do happen:
  • Chernobyl
  • Or, more recently, Fukushima in Japan
  • But I want you look at this data. A terawatt-year is one terawatt of power consumption, maintained for a year: for reference, the world’s average electricity usage is slightly over sixteen terawatts. It’s from a 1998 study commissioned by the Swiss Federal Office of Energy. There’s a simple reason that the coal death rate is so high: air pollution. Especially in newly industrialised countries like China, with looser restrictions, the huge amounts of soot and other pollutants are incredibly dangerous, killing hundreds of thousands every year, and let’s not forget mining accidents.But why is hydro so lethal? It has been distorted hugely by the Banqiao Dam disaster of 1975, in which 170,000 people died.The point of this slide is to get some perspective. The Banqiao dam was a dam with inadequate safety features, and when it collapsed over a hundred thousand people died. Chernobyl was a poorly-maintained nuclear plant with inadequate safety features, and when a reactor exploded, nobody’s quite sure how many died, but most estimated put it at between eight thousand and fifty thousand.
  • In nuclear fission, the uranium-235 is reacted, but the uranium-238, as well as various other elements formed, is left behind. Some of these elements are radioactive, and pretty unpleasant. Anybody here fancy living next to drums of radioactive waste?This is a pretty big problem. So what do we do? We bury it, that’s what we do.
  • Welcome to the Waste Isolation Pilot Plant, Carlsbad, New Mexico, USA. How this place works is simple. Engineers have dug a shaft six hundred and fifty metres down, and are now excavating huge rooms, into which drums of waste are to be placed. Once the site is full, which will happen in around 2038, it will be sealed off, as the waste will remain potentially harmful for around ten thousand years. This area is very geologically stable, so there is a very low risk of earthquakes, and any fissures in the rock are sealed naturally. Burying waste is by no means a perfect solution, but it’s the only thing we really can do.But consider this. Nuclear energy generates small amounts of environmentally damaging waste. Fossil fuels, especially coal, generate large amounts of waste in the form of atmospheric carbon dioxide. While less harmful when compared directly, given how much more is produced from coal, the dangers of climate change seem far more threatening. And at least you can bury the nuclear waste – once greenhouse gases are in the atmosphere, good luck getting them out.
  • The answer to this is fairly obvious. No. There’s a certain amount of uranium, or any other fuel, in the ground, and once we run out, that’s it. But the real question is not whether it will last forever, rather it is: do we have enough nuclear fuel to last for the foreseeable future? This answer is much more complicated.
  • With current reactor types, the longest estimates are only a few hundred years, the shortest say that peak uranium has already happened. This doesn’t look much better than oil, gas or coal.But there’s a big catch there. With current reactor types.
  • Uranium, as it comes out of the ground, contain several isotopes: forms of an atom that have the same number of protons, so they’re the same element, but have different numbers of neutrons. In blue here is uranium-238, and in red is uranium-235.The only type which will undergo fission? You guessed it. Uranium two three five.
  • Enter a technology called breeder reactors. These are reactors which can “breed” one isotope of an element into an entirely new element. The most common, and indeed the only technology that’s ever been used commercially, converts Uranium-238, that 99.3% of Uranium that we thought was useless, into plutonium-239. This is, like uranium-235, fissile: it can be used in a reactor.Suddenly, we go from...
  • This...
  • ...to this.So why don’t we use breeder reactors commercially now? Simple. At the moment, it’s cheaper to just buy more uranium. Commercial power stations have been run this way, but they were closed down simply because normal uranium supplies were, and still are, cheaper. Or course, this will change if uranium prices go up, as has happened with oil in the past few years.This isn’t all that can be done with breeder reactors, by any means: thorium-232, which is four times more abundant than uranium, can be bred into uranium-233, another fissile isotope.This gives us hundreds, probably even thousands of years more fuel, long enough for future energy sources such as fusion to be developed.
  • This is another potential problem: could rogue states, or terrorists, get hold of nuclear material?
  • As you’ve seen, uranium, in its natural form, can’t go straight into the reactor. It’s mostly uranium-238, and needs to be enriched – have its concentration of uranium-235 increased. This is done with centrifuges, and has to be done whether it’s going into a power plant or into a bomb, but there’s a crucial difference.
  • Here’s the composition of natural uranium again.
  • And here’s how it needs to be enriched for power production. But if you want to make a bomb, you need
  • ...this as an absolute minimum, and preferably something closer
  • To this. So nuclear fuel simply cannot be used in a bomb without enriching it further, and gas centrifuges are notoriously hard to build. There is another concern, though. Terrorists might have trouble building a nuclear weapon,
  • ...these guys might find it easier. MahmoudAhmedinajad, President of Iran, and Kim Jong-Un, Supreme Leader of the Democratic People’s Republic of Korea. Whether or not they are actually building bombs is beyond the scope of this talk to investigate, as is whether they should be allowed to do so, but they both have nuclear programs, and Iran for one is certainly claiming its centrifuges are for peaceful power generation. This, however, is not a problem of technology, but of politics: even if we were to drop nuclear power today, a sovereign state like Iran or North Korea could develop its own technology.
  • To finish off this presentation, I’d like to look at Germany. Why? The accident at the Fukushima Dai-ichi Nuclear Power plant two years ago was not a pleasant occurrence. Large numbers of people had to be evacuated, crops and livestock were contaminated, and it only served to make life even harder in a region already devastated by the tsunami. But it also had consequences far away from Japan. In Germany, thousands of people protested to try and persuade their government to move away from nuclear power, and within days, the chancellor Angela Merkel announced that some of the country’s reactors would be shut down immediately, with others to be decommissioned within ten years.But when you shut down seventeen power plants at the drop of a hat, you need electricity from somewhere. While plans were announced to build wind farms in the North Sea, that will take several years. So where’s the power coming from?
  • It’s coming from the Czech republic. And where does most Czech power come from? Coal. Dirty, dusty, polluting, CO2-emitting coal. As I mentioned previously, while nuclear accidents can be extremely harmful to our planet, coal plants pollute every day.
  • Is nuclear energy nice? No. Do I think it is completely safe? No. Do I want to live in a world where the risks of accidents are very real? No. But am I in favour of it? Absolutely.I think nuclear power is a very unpleasant thing. So why am I stood here telling you it’s the solution to our energy problems? Because I believe it is. Why? Yes, we can use renewable power, and I absolutely think we should. But it is impossible for such sources to supply the world’s massive needs. So ultimately, it’s
  • Nuclear, or it’s
  • Coal
  • Oil
  • And gas.
  • And if we choose coal, oil and gas, we are on track for a climate disaster.Nuclear energy is not entirely safe. It won’t last forever. But, despite its flaws, we absolutely need it. Thank you for listening.

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