Progress toward fusion energy gain as measured against the Lawson criteria

Original Article ↗ Hacker News Discussion ↗

Apparent Progress Gap (2000–2020)

  • Commenters notice the Lawson / Q plots are sparse between ~2000–2020.
  • Explanations offered: focus and funding shifted to ITER; major DT tokamak campaigns are rare; many machines in that period were smaller, non-DT, or exploring engineering concepts (e.g., high‑temperature superconducting magnets), which don’t show up strongly on Q_sci plots.
  • The article’s author notes that Q_sci data effectively requires DT fuel, and only a few tokamaks have run DT.

ITER: Research Flagship or Dead End?

  • One side: ITER is in “development hell,” badly delayed and over budget; critics argue its power density and economics will never be competitive, and that it has crowded out alternative approaches.
  • Others counter that ITER is explicitly a research device, not a power plant, aimed at understanding large‑scale tokamak plasma and demonstrating technologies (neutral beams, divertors, complex vacuum construction).
  • Disagreement over whether DEMO‑like follow‑ons based on ITER physics can ever reach acceptable power density versus fission.
  • Some emphasize ITER’s global manufacturing “ecosystem” and spin‑offs (e.g., superconductors), others see it as a “jobs program” with intentionally unrealistic cost estimates.

High‑Temperature Superconductors and Compact Tokamaks

  • New commercial HTS tapes enable much higher magnetic fields and more compact tokamaks; companies like Commonwealth Fusion Systems are built around this.
  • ITER uses HTS only in current leads, not main coils; several commenters argue it was locked into older LTS technology by its design era.

NIF, Weapons vs Power, and Laser Efficiency

  • Broad agreement: NIF was built primarily for nuclear weapons stockpile stewardship, not as a power-plant prototype.
  • It uses inefficient, 1990s‑era lasers; modern systems could be ~40× more efficient and higher repetition, but even then large gains in capsule performance and repetition rate would be needed for power production.
  • Debate on whether laser fusion remains a “technological dead end” for energy versus a potentially viable path if efficiency and gain improve another order of magnitude.
  • Clarification that NIF’s reported “gain” is fusion energy vs laser energy on target, ignoring wall‑plug losses; it has achieved scientific net gain but not facility‑level net power.

What “Breakeven” and Q_sci Actually Mean

  • Multiple commenters stress that “breakeven” is ambiguous:
    • Scientific breakeven: fusion energy out vs heating energy into the plasma (or capsule) across the vacuum vessel boundary (Q_sci).
    • Facility/system breakeven: net electrical energy out vs total electrical energy in (“wall‑plug” efficiency including drivers, plant, and turbines).
    • Economic breakeven: paying back capital and operating costs.
  • The article and thread emphasize being precise about which boundary and which Q is being discussed.

Commercialization, Startups, and Timelines

  • Several well‑funded efforts (tokamaks with HTS, alternative magnetic concepts, pulsed inertial fusion) are targeting scientific net gain before ~2035.
  • Some participants think scientific viability by ~2035 is plausible; economic viability is expected to lag significantly.
  • Classic “fusion is 30 years away” skepticism persists; others point to accelerating progress and multiple independent approaches as reasons for optimism.

Fusion vs Fission vs Renewables

  • One camp argues fusion funding is small compared to the cost of a single modern fission plant, and that money should instead go to next‑gen fission (including molten salt) to decarbonize now.
  • Counter‑arguments:
    • Solar+long‑duration storage is still costly; grid‑scale batteries today are mostly 4‑hour systems.
    • Nuclear provides dispatchable, high‑temperature heat for industry; renewables don’t trivially replace that.
  • Intense sub‑thread on nuclear waste:
    • Critics argue long‑lived waste (hundreds of millennia) is unsolved and morally burdens future generations.
    • Pro‑nuclear voices cite deep geological repositories (e.g., Finnish projects), reprocessing, small absolute waste volumes, and stress that climate risk from CO₂ is far more urgent than far‑future waste hazards.
    • Some oppose new fission on principle; others call this stance irrational given relative risks.

Other Concepts and Experiments

  • Interest in:
    • New stellarator designs derived from W7‑X.
    • Pulsed inertial fusion concepts (e.g., Pacific Fusion’s pulser‑driven approach).
    • Impact‑driven inertial fusion (First Light Fusion’s gun/coil‑gun concept), with early triple‑product data but no clear consensus on viability.
  • Some view the landscape as a “fusion race” analogous to the space race; others note that even if fusion never becomes mainstream power, the research is scientifically rich.