HELIARC — fusion power from Lodestar, a stellarator at Skerra Head
HELIARC · Fusion power
We builta star.
The sun has run on fusion for four and a half billion years. Lodestar does the same thing in a hall at Skerra Head, and sends the power down a wire.
01 · The reaction
Two kinds ofhydrogenbecome helium.
Deuterium and tritium are heated until they collide hard enough to fuse. Each reaction releases 17.6 million electronvolts, about four million times more energy per kilogram than burning coal.
- Per reaction
- 17.6 MeV
- Fuel per day
- 280 g
- Carbon
- 0 g
02 · The machine
A magneticbottle, twistedto fit.
Lodestar is a stellarator. Fifty superconducting coils, each bent into its own three-dimensional shape, hold the plasma in a twisted ring without it ever touching the wall. No current runs through the plasma, so it cannot suddenly let go.
- Coils
- 50
- Field on axis
- 9.6 T
- Coil temperature
- 20 K
03 · The plasma
150 milliondegrees, a metrefrom the cold.
It is ten times hotter than the centre of the sun, held in a vacuum by field lines that wind round the ring like thread on a spool. The tungsten wall it never touches is lined with the lithium that breeds the next fuel.
- Ion temperature
- 15 keV
- Density
- 2 × 10²⁰ m⁻³
- Operation
- Steady state
05 · The fuel
The fuel isin the sea.
A litre of seawater holds enough deuterium to match three hundred litres of petrol. Tritium we breed ourselves, from lithium, inside the walls of the machine. Nothing it leaves behind lasts longer than a lifetime.
- Deuterium
- 33 mg / litre
- Lithium
- Bred in place
- Long-lived waste
- None
06 · Lodestar One
Four hundredmegawatts,day and night.
That is enough for seven hundred thousand homes, whatever the weather, from a site the size of a supermarket. Construction starts at Skerra Head in 2027. First power is planned for 2033.
- Net output
- 400 MWe
- Homes
- 700,000
- First power
- 2033
04 · The power
From neutronto national grid.
Four-fifths of the fusion energy leaves the plasma as fast neutrons. The blanket stops them, turns them into heat and breeds tritium as it does. Steam does the rest.
- Gain, Q
- ≈ 25
- Efficiency
- 40 %
- Net
- 400 MWe
HELIARC · Skerra Head · Edinburgh
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MagnetsHTS coil winding engineerSkerra HeadPlasmaStellarator optimisation physicistEdinburghBreedingLithium blanket chemistEdinburghOperationsControl room shift leadSkerra HeadThe build log
One letter a month from Skerra Head: the magnets, the milestones, the setbacks.