This article is from the Fusion FAQ, by Robert F. Heeter firstname.lastname@example.org with numerous contributions by others.
First we need some definitions:
"Reserve" = amount of a given substance which we know we
can extract today at current prices with current technology.
"Resource" = amount of a substance which is present in the
earth which could conceivably be extracted.
In general, reserves of fusion materials are sufficient for
all current needs, and resources are sufficient for all projected
future needs for millions of years to come.
- Fuel: D is very abundant; T can be made with blanket (see below)
- Neutron Blanket:
Lithium (Li) (which will be used to breed tritium (T))
is abundant in seawater as well as in the crust. Current
reserves (Li is mostly obtained through mining on land)
are 2.21 million metric tons, sufficient to build probably
hundreds of reactors. Oceanic resources are sufficient to
meet current and projected world energy needs for millions
of years to come, without costing significantly more.
- Reactor Structure:
Silicon Carbide (SiC) and Vanadium or Vanadium-Titanium
alloy are the primary candidates for reactor structures.
Carbon of course is everywhere; silicon is also highly
abundant. Reserves of vanadium are currently 4.27 million
metric tons; Vanadium is present in many minerals not
currently used as ores, so the total resource is
significantly larger. Reserves of titanium are currently
288.6 million metric tons. (Source: _World Resources 1992-1993_)
A 1000 MW fusion reactor would use on the order of 1000 tons
of vanadium, most of which could probably be recycled from
one reactor into a new one (after a waiting period of tens of
years for the radiactivity to decrease). So vanadium reserves
will not be stretched until probably hundreds of fusion reactors
have been built, by which time new reserves will most likely
be available. (This does take into account other uses of vanadium.)
- Magnet Materials:
We're not sure just what future fusion reactors will use for
their electromagnets, primarily because superconductor technology
is still evolving. Reactor designs generally try to prevent
radiation damage to the magnets (which could destroy their
superconductivity) so magnets are not generally consumed in a
reactor; to my knowledge there is no projected shortage of