Of Coconut Futures and Thermonuclear Fusion Power
There may soon be a run on coconut futures. Vintage 2002 Indonesian coconut-shell charcoal is being used to help build what may become the first commercially viable Tokamak fusion power electrical generating facility near Cadarache in the south of France – about 38 miles from the Mediterranean.
Tokamak (from the Russian for “toroidal chamber with magnetic coils”) is a type of magnetic confinement device for producing controlled thermonuclear fusion power. The coconut charcoal is an environmental sponge that “adsorbs” the helium and hydrogen byproducts of the thermonuclear fusion reaction.
In what sounds like it could be the beginnings of a Star Trek-like Federation, the United States has joined the European Union, Japan, the Russian Federation, China, Korea, and India in negotiations for the establishment of the burning plasma prototype facility called ITER, which in Latin means "the way."
The fusion power produced by ITER will be at least 10 times greater than the external power delivered to heat the plasma. It’s not quite a Starship warp drive, but it does harness the power of the sun.
ITER is expected to cost more than $10 billion. Skeptics point out that ever since the idea of fusion power was first touted in the 1950s, fusion’s promise of clean power has receded endlessly into the future. Here’s a short video on the promise of ITER:
The Tokamak building is the core of ITER, where fusion experiments are planned to start in 2018. The reinforced concrete structure will sit with 5 1/2 stories underground and nineteen stories above. Adjacent to the main building, an assembly hall will be the location for pre-assembly of Tokamak components.
In ITER, the fusion reaction is achieved in Tokamak using magnetic fields to contain and control hot plasma. The fuel –- a mixture of deuterium and tritium, both isotopes of hydrogen –- is heated to temperatures in excess of 150 million°C, forming helium and neutrons in addition to the hot plasma. A helium nucleus carries an electric charge that responds to the magnetic fields of the Tokamak, and remains confined within the plasma. Approximately 80% of the energy produced is carried away from the plasma by neutrons — a neutron has no electrical charge and is unaffected by magnetic fields. The neutrons are absorbed by the surrounding walls of the Tokamak, transferring their energy to the walls as heat.
This is where the coconuts come into the picture. The coconuts will be used to generate a cooling vacuum essential to ITER’s operation. In the central chamber, some of this vacuum separates the plasma from the surrounding solid walls and allows fusion to proceed unhindered by air molecules. The vacuum pumps suck air out of ITER and “adsorb” waste helium from the fusion reaction, along with other debris created when hot plasma smashes into the reactor wall.
"This can only be done with very large cryogenic pumps," says Christian Day of the Karlsruhe Institute of Technology in Germany. The cryogenic pumps capture loose helium and hydrogen through a process that involves atoms of the gases sticking loosely to a solid surface — the greater the surface area, the better. "We wanted a material that behaves like a sponge, with lots of internal surfaces," Day adds. After 20 years searching for the ideal adsorber –- including sintered metals and porous minerals called zeolites –- Day’s team decided on charcoal. And not just any charcoal. "We found that coconut-shell charcoal is the best," Day says. "It is somehow strange that you need this very natural material to make a fusion device."
Only one immediately available source does not cause global warming and that is nuclear energy, says Lovelock.
Thermonuclear fusion and coconuts – strange bedfellows. But is fusion energy really "the way?" as the name ITER suggests? Why bother to build a fusion reactor when there is an almost inexhaustible supply of energy from the sun? Why not spend the $10 billion (or probably more) on wind or solar power instead?
A New Scientist editorial makes the case: "Compared with the more exotic schemes for large-scale manipulation of the environment now coming under serious consideration –- which do look 50 years away –- fusion power is a racing certainty. It’s safer too. A technology that messes with our planet’s climate is what got us into trouble in the first place." Ecologist James Lovelock –- concerned that humanity will shortly be facing a series of catastrophes from global warming –- might agree with this assessment. “By all means, let us use the small input from renewables sensibly, but only one immediately available source does not cause global warming and that is nuclear energy,” says Lovelock.
Lovelock – famous for the “Gaia hypothesis” – refers to conventional nuclear fission power generation (with all its attendant radioactive waste byproducts), but he is essentially making the case that humanity can’t afford to wait for “more exotic” technologies like solar and wind (and possibly fusion) to come online because he feels that a reduction in greenhouse gas emissions needs more immediate action.
This isn’t to say that both sun-based solar and man-made fusion can’t coexist to help meet the world’s energy needs. According to ITER, fusion power stations producing 1-2 GW should be feasible within ten years – much the same size as standard fossil fuel power stations. Proposed space-based solar power from Solaren Corporation (see the h+ article Space-based Solar is Coming!) offers the possibility of scaling up to the same 1-2 GW range by 2020. Nanosolar, another solar start-up company, is building a solar cell production facility projected to generate 430 MW annually.
It’s good to know that there are options — and it’s ironic that the world’s 21st Century energy future could end up being a race between harnessing power from real and artificial suns. With fossil fuels “messing” with our climate, as both Lovelock and New Scientist suggest, it seems we’d best keep all our cards (and coconuts) on the table.