Reproducing the sun on Earth: nuclear fusion
Hanoverschen Allgemeinen Zeitung, 06.10.07 - The figures defy the imagination: a single gramme of this new fuel is theoretically capable of providing 50,000 kWh of energy - the equivalent of 6 tonnes of coal. This material of such a colossal energy content is called deuterium and can be found practically everywhere, in ordinary water. Deuterium is a form of hydrogen which is a little heavier than the normal gas. If we could extract sufficient deuterium, from water or from the ground, for power generation, we could produce as much energy with 1 km3 of sea-water as with all the known oil reserves in the world.
But to do this, we must provoke the fusion of two hydrogen nuclei with one helium nucleus, which requires the initial input of a vast amount of energy: enough to achieve a temperature of 100 million degrees Celsius. The problem is not how to produce such a temperature, but how to maintain it. Because everything disintegrates at such high temperatures, even atoms themselves. This process, going on all the time in the sun, in which two hydrogen nuclei fuse with one of helium, is called nuclear fusion. The resulting catapulting of energy into space is what we feel on Earth as heat or a heat wave. A fusion reactor would be a sort of mini-reproduction of the sun.
The risks involved in nuclear fusion are minimal, in contrast to those associated with nuclear fission in power stations. If ever the plasma managed to escape from the containing magnetic fields during the fusion and reach the reactor walls, the walls would start to melt, but only a small part would be affected because the process would immediately be brought to a halt, as when one shuts off the gas supply to a furnace. In nuclear fusion, there is no danger of a runaway chain reaction, as is the case with nuclear fission.
Nuclear fusion would also produce some radioactive waste, which would have to be stored for a few hundred years, but this is a much shorter period than that required for the highly radioactive fission by-products from conventional nuclear power stations, whose half-lives run to several thousand years.
To investigate whether and how nuclear fusion can be rendered operational, an experimental reactor is under construction at Cadarache in France, known as ITER. In order to meet the project's costs, estimated at 10 billion euros, the European Union, the United States, Japan, India, Russia, South Korea and China have pooled resources.
No-one can predict today how much electricity produced by nuclear fusion will cost. We do not even know whether it can be made to work. Critics talk of the "50 years" constant: scientists always give the same answer, when asked how much longer we need to wait before it will be possible to generate energy by nuclear fusion: "another 50 years". It is the same response today as ten years ago.
Summary of an article published in the Hannoversche Allgemeine Zeitung.
Translation Nicholas ROSE
It is the thirteenth non-renewable resource set to disappear thanks to intensive exploitation by mankind.
Remaining world deposits of this energy resource are estimated at 3.93 million tonnes. This figure corresponds to ores that can be exploited at a permissible cost.
June 2008: at current rates of production, 64,000 tonnes per year, deposits will last 32 years.
Extractable deposits of this radioactive heavy metal will therefore disappear for good in 2040. This date is contested by certain studies. However, the exhaustion date will be some time between 2025 and 2060.
For example, the following figures come
from the Energy Watch Group's paper "
Uranium Resources and Nuclear
Energy" (December 2006):
See also: http://www.futura-sciences.com (in French)
Others estimate the world's uranium reserves at over 5.5 million tonnes, which could keep the world's 435 existing reactors going for a century.
According to the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, known uranium reserves will even last for 200 years, if consumption is held at its present rate of 64,000 tonnes per year.
Even if these figures proved reliable, this would not take into account the new nuclear power stations currently under construction across the world. 36 new reactors are already under construction in 2008, without counting the 311 projects still at the planning stage, which are set to double the number of nuclear power stations worldwide.
Uranium's sole application is nuclear power stations for the production of electricity.
About thirty countries in the world have the advanced technology necessary to generate nuclear power. But how many others dream of climbing onto the bandwagon? The sale of nuclear power stations has now become the business de certain heads of states who don't stop to think.
Problems arising from its disappearance will start to make themselves felt well before the fateful date, whichever it may be. On this subject, see Hubbert's peak theory: https://en.wikipedia.org/ Of course, there will still be uranium in granitic and sedimentary rocks, and even in sea- and river-water, but in extremely diluted form, rendering extraction impossible.
Even if, thanks to advances in technology, we find new deposits by digging deeper and deeper into the Earth's crust, this will afford us only a few years' reprieve and will not make a major impact on the situation.
Uranium was created when a star exploded and the Sun and the Earth were formed from the debris, over five billion years ago.
You cannot produce it artificially and there is no substitute.
Thorium could take over, but not for long. It would only provide relief for a few decades for a very small fraction of the world's population.
The Moon and the asteroids do not contain uranium in an extractable form. And just imagine the energy it would take to bring some back from Mars or Venus!
When the newly spent uranium rods from the nuclear power stations are retreated, at The Hague for example, a chemical process is used to re-extract the uranium and the plutonium, which are combined in oxide form to produce MOX (Mixed OXide fuel), which is then recycled in nuclear power stations to reproduce electricity again.
A Japanese team has recently demonstrated that it is possible to extract uranium from sea-water (3 mg/tonne) using a suitably textured adsorbent. For the time being, the process is prohibitively expensive and would require a great deal more energy than it would produce, but it could open up access to reserves 1000 times greater.
One of the best nanotechnology blogs proposes the application of similar technology for lithium, which is present at a concentration of 170 mg/t in sea-water, and the use of a nano-membrane to concentrate the solution in which the adsorbent is immersed. The use of algae is also suggested.
For the time being, this "project" would appear Utopian, or, at the very best, at an embryonic stage of development.
The price of uranium has risen tenfold in four years.
The big problems with uranium are the management of the waste, radioactive for thousands of years, the accidents involving reactors or circuits and the multiplication of nuclear warheads, in spite of non-proliferation treaties. There are currently 26,720 of these murderous weapons in the world, enough to destroy all life on Earth in the space of a few minutes.
The peaceful fission of uranium produces a highly radioactive residue, plutonium, first made in 1940, which does not exist in a natural state, and which is used nowadays to produce increasingly destructive weapons.
The plutonium can be separated from the spent fuel rods by chemical reprocessing. As long as it is trapped in the spent fuel rods after fission, it is of no use for the production of atomic bombs.
It is worth noting, however, that plutonium could serve as a fule for a new generation of nuclear power stations and thus push back the end of fissile nuclear energy a few years.
However, as we have seen, the nuclear industry, even under proper control, is not a sustainable solution. It will inevitably remain an extremely limited energy source on a world scale.
Translation Nicholas ROSE
Don't miss reading Point of view by Michel Walter, a programme for the end of our civilisation of wastage.
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