Breakthroughs Enabling THermonuclear-fusion Energy

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Program Description:

Breakthroughs Enabling THermonuclear-fusion Energy (BETHE) supports the development of timely, commercially viable fusion energy. Building on recent progress in fusion research and synergies with the growing private fusion industry, this program aims to deliver a larger number of higher maturity, lower cost fusion options via three research categories: (1) Concept Development to advance the performance of inherently lower cost but less mature fusion concepts; (2) Component Technology Development that could significantly reduce the capital cost of higher cost, more mature fusion concepts; and (3) Capability Teams to improve/adapt and apply existing capabilities (e.g., theory/modeling, machine learning, or engineering design/fabrication) to accelerate the development of multiple concepts. BETHE’s technology-to-market component aims to build and smooth the path to fusion commercialization to include public, private, and philanthropic partnerships.

Innovation Need:

Controlled fusion has long been thought of as an ideal energy source—safe, clean, and abundant. Based on numerous studies examining the cost challenges facing advanced nuclear energy—which shares unit size, capital cost, and power-generation attributes with fusion—ARPA-E believes that a commercial fusion power plant should target an overnight capital cost of <US$2B and <$5/W. If a grid-ready fusion demonstration can be realized within approximately 20 years while satisfying these cost metrics, then fusion can contribute to meeting growing global, low-carbon energy demand and achieving cost-effective deep decarbonization in the latter half of this century.

ARPA-E's first fusion program, ALPHA, focused on developing potentially transformative fusion concepts and related technologies (i.e., pulsed, intermediate-density fusion concepts) that could significantly lower the costs of fusion development and eventual deployment. Today, a growing number of privately funded fusion companies are pursuing these and other approaches that potentially offer reduced cost, size, complexity, and generation capacity. However, it is difficult for lower-cost fusion concept developers to secure enough funding to meet performance milestones, much less realize a grid-ready fusion demonstration. This unsustainable situation for lower-cost fusion concept development is a strong motivator for the BETHE program.

Potential Impact:

Fusion must accelerate development and lower the costs of development and deployment in order to have a significant impact this century. Benefits include:


Development of timely, commercially viable fusion energy would ensure the U.S.’s technological lead and energy security.


Fusion can significantly improve our chances of meeting growing global clean-energy demand and mid/late-century carbon-emissions targets.


Fusion has the potential to offer abundant, reliable, highly dispatchable power and could help enable a cost-effective, global low-carbon energy economy.