JASON Panel reviews ARPA-E Fusion Effort

January 27, 2019

In 2014 the US Department of Energy ARPA-E initiated a three-year $30M program called ALPHA to explore magneto-inertial fusion (MIF) concepts in a range of plasma density lying between the magnetic confinement (lower density) and inertial confinement (higher density) approaches to fusion. ALPHA's goal was to identify ways to accelerate progress toward fusion power. With the ALPHA program nearing completion, ARPA-E asked JASON (a prestigious scientific panel) to assess its accomplishments and the potential of further investments in this field. JASON members listened to two days of briefings that included participants in ARPAE's ALPHA program, MIF teams not supported by ALPHA-E, and teams working on pure magnetic confinement fusion. JASON also surveyed nine teams for quantitative metrics of past, present, and projected progress along critical physical parameters. Their report, titled "Prospects for Low Cost Fusion Development" was completed in late November 2018, The Executive Summary is provided below.


Controlled thermonuclear fusion has been pursued for more than 60 years. In recent decades, US funding has focused on laser-driven inertial confinement (ICF) for national security purposes and on magnetic confinement (MCF), primarily in tokamaks, for energy production. The major component of the latter international program is the $25B ITER project, expected to begin DT operation in 2035.

The findings of this study are summarized as follows:

  1. Magneto-Inertial Fusion (MIF) is a physically plausible approach to studying controlled thermonuclear fusion in a region of parameter space that is less explored than Inertial Confinement Fusion (ICF) or Magnetic Confinement Fusion (MCF).
  2. MIF research is immature. Despite having received ~1% the funding of MCF and ICF, MIF experiments have made rapid progress in recent years toward break-even conditions, and some (e.g. MagLIF) are within a factor of 10 of 'scientific break-even'.
  3. There are many plausible and distinct approaches to MIF. Some early projects supported by the ALPHA program are showing rapid progress in critical physical parameters and have not yet reached insurmountable obstacles. As in ICF and MCF, instabilities may make scientific break-even MIF more challenging than simple scaling estimates suggest.
  4. ALPHA program support for development of broadly applicable technologies has accelerated progress of multiple efforts. All MIF approaches would benefit from improved understanding of plasma instabilities and liner-plasma interactions, better computational tools, and improved diagnostics.
  5. While scaling from current experiments is uncertain, it is likely that reaching scientific breakeven with a single MIF prototype will cost at least several $100M and possibly much more. Considerably larger expenditures would be required to go from scientific breakeven to a demonstration power plant; and even more from a demo to a production capability.
  6. Given the immaturity of the technologies, the future ability of fusion-generated electricity to meet commercial constraints cannot be usefully assessed. Rapidly developing infrastructures for natural gas and renewable energy sources and storage will compete with any future commercial fusion efforts. Nevertheless, there is a small but growing private-sector community investing in and pursuing commercial fusion projects.
  7. The pursuit of MIF could lead to valuable spinoff technologies, and to non-power fusion applications, with broad civilian and military import. Some approaches have low enough mass to be candidates for space propulsion, but it is too early to impose the relevant design constraints (low weight, low thermal dissipation) on ongoing research.
  8. MIF research could productively absorb a significantly higher level of funding than the $10M/yr of the ALPHA program.
These findings lead to the following recommendations:
  1. MIF activities should be supported by an investment in basic research to:
  2. The National Laboratories should contribute their unclassified state-of-the-art simulation codes to collaborations with academic and commercial efforts, and support training of qualified users.
  3. Targeted technology development programs should focus on development of components, including plasma guns (high Z and low Z), pulsed power and electronics, diagnostics, and advanced magnets and materials.
  4. The near-term goal should be scientific break-even (thermonuclear energy out > mechanical + electromagnetic energy into the fuel) in a system that plausibly scales to a commercial plant. Until that goal is achieved, set aside questions of neutron economy (tritium breeding) or balance of plant. Pursue system integration only insofar as it is needed to demonstrate scientific break-even.
  5. Explore pulsed neutron sources and space propulsion as motivating applications with different constraints than grid electricity. Efforts in these speculative directions should supplement, not replace, basic MIF research.
  6. Support all promising approaches for as long as possible. Do not concentrate all resources on early front runners.

Copies of the full report are available at: https://arpa-e.energy.gov/?q=site-page/prospects-low-cost-fusion-development

The full report contains the following addendum as commentary on the report by ARPA-E:

ARPA-E is grateful to JASON for conducting this study and for their insightful findings and recommendations.

Here, we provide commentary related to their finding #6: "Given the immaturity of the technologies, the future ability of fusion-generated electricity to meet commercial constraints cannot be usefully assessed..." This is a fair statement given the large uncertainties in the state of the technology and in the future needs of the U.S. and world electricity markets. However, in the view of ARPA-E, some of the analysis in Sec. 2.3 (Fusion in the Energy Landscape) does not adequately capture the full range of potential outcomes for either the technology or for the market needs.

Section 2.3 includes some analysis based upon a maximum levelized-cost-of-electricity (LCOE) of $0.05/kWh, which is drawn from the current estimate for natural gas combined cycle (NGCC) electricity generation, and leads to a rough estimate of a maximum allowable overnight capital cost of $5.55/W. This is compared against a notional $6.67/W fusion power plant from the referenced Bechtel cost study. However, the latter, which examined the cost drivers for four fusion-core concepts applied to a 150-MW point design, was intended to identify the main cost levers, not to arrive at accurate, absolute capital cost estimates for a future fusion plant. In fact, the study was based upon costing models for nuclear fission plants that are already known to be well above costs being achieved in other parts of the world. For example, Korea has repeatedly shown that present-generation fission plants can be built for roughly $2/W. Thus, conclusions drawn based on capital cost estimates from the Bechtel study could be overly pessimistic.

From the standpoint of market needs, a benchmark of NGCC in the current context of the U.S. grid does not adequately capture global markets and/or market segments where fusion might be first adopted, or the future needs of the electric grid. Benefits of fusion that do not factor into such an analysis include:

In fairness, NGCC does address some of these considerations as well, but these features are not well captured by the $0.05/kWh LCOE figure. The JASON study does note that there are applications that can justify electricity costs well above the notional $0.05/kWh, and that the likely largest market for fusion energy may not be in the U.S. In addition, the study acknowledges that there are certain markets within the U.S. where there are income streams for ancillary services that can meet or even exceed the value of selling baseload electricity. These caveats serve to remind us that directly comparing early estimates for fusion-plant capital costs with income based on current U.S. LCOE projections for NGCC is too restrictive to assess the future market attractiveness of fusion power.

Beyond the specific details of the cost analysis, the JASON report highlights the importance of including cost analyses in assessing the potential real-world impact of fusion (or any energy technology). This is a message that ARPA-E appreciates, and we hope that the fusion R&D community will embrace this attitude as it continues to make progress.