Haven't seen this come up around here before, but in the attached video a pretty good case is made for heavy ion fusion:
http://www.youtube.com/watch?v=2emKoMgZ03U
http://www.fusionpowercorporation.com/corporation
need to be big to overcome the ignition requirements - end up with a 8-10km long linear accelerator with beam pulses switching between up to 20 chambers each with 10GJ output pulses. Output is about 100GW and each chamber repeats at 0.5-1Hz. Total cost $20-30 billion (ie ITER level)
Targets are lead encased D-T cylinders heated then ignited by an ion beam from each end. Chambers are filled with sheets of sprayed lithium at high temperature to absorb all neutrons and eliminate first wall and neutron activation issues, lithium is collected at 1100°C and heat used to make hydrogen in sulphur iodine cycle to make hydrogen for hydrocarbon fuels, with waste from that process making electricity - 60-70% of heat energy can be used productively.
Advantages:
-High efficiency (20-30%) continuously run driver (unlike laser).
-Single driver can be switched between many chambers.
-High fusion gains of up to 1000:1
-Simple target chamber with only a couple of tiny beam and target apertures
-Chambers can be individually developed, improved, maintained and swapped out over time.
-Almost no radiological waste.
-Almost zero potential for life-threatening accidents.
-No proliferation risk.
-All technology required appears to be at high readiness level (adapted from particle physics etc), the required technology has been available for 30 years.
-Would produce lower cost power than any other known power source.
-Can provide $50/barrel oil using hydrogen + atmospheric CO2, eliminating oil and gas extraction industries.
-Could be running in 10 years.
-Compatible with existing infrastructure (cars, planes, ships, grid)
-2-300 plants worldwide would supply all of humanities projected energy needs
Disadvantages:
-sticker shock - need $10-20 billion to build a plant at sufficient scale to prove it works.
-large size is awkward for grid integration.
-8km long linear accelerator and 30GW heat dissipation - probably need to be next to sea, but then waste heat can also desalinate.
Conclusion:
For a similar investment and shorter time scale than ITER you could have something that was actually economic and would solve all of worlds power problems. Seems like a much better bet than other fission or fusion proposals.