TL;DR: If you are replacing Helion Energy, the closest options are Boost Biomes, ThereCraft, Prometheus. The table below compares 12 alternatives on what they do, stage, size and status.
Every alternative below is compared on what it actually does, not just its category — so you can see which one genuinely replaces Helion Energy (YC Summer 2014).
Last verified:
The three closest alternatives to Helion Energy are:
| Alternative | What it does | Stage | Team | Status |
|---|---|---|---|---|
| Boost Biomes | — | YC Summer 2019 | 12 | Inactive |
| ThereCraft | — | YC Summer 2017 | 1 | Active |
| Prometheus | We use solar and wind power to make zero net carbon electrofuels | YC Winter 2019 | 25 | Active |
| Airthium | Decarbonized heat and power cheaper than fossil fuels | YC Summer 2017 | 18 | Active |
| Maritime Fusion | Fusion reactors for ships | YC Winter 2025 | 6 | Active |
| Intelline | Intelline makes the world's most efficient fuel agnostic engines for… | YC Winter 2019 | 3 | Active |
| Zephyr Fusion | Powering tomorrow's industrial revolution in space | YC Fall 2025 | 2 | Active |
| Apollo Atomics, Inc. | We make the most compact nuclear reactors | YC Spring 2026 | — | Active |
| Phykos | Growing seaweed to stabilize the climate. | YC Summer 2021 | 2 | Active |
| Dipole Labs | AI-controlled optical switching for AI clusters | YC Summer 2026 | — | Active |
| Kapacity.io | Reducing energy costs & emissions in buildings. | YC Summer 2021 | 7 | Acquired |
| Validere | A carbon MRV solution for energy and hard-to-abate sectors | YC Summer 2016 | 110 | Active |
It depends on your size. Boost Biomes is the closest match on what Helion Energy actually does. If you need something more established, sort the table by team size — larger teams generally mean more support and a longer track record. If budget is the constraint, the earlier-batch companies are usually the ones still competing on price.
Helion Energy is still operating, so switching is a choice rather than a forced migration. Compare on fit and price rather than urgency.
Every company here is Y Combinator-backed and was matched to Helion Energy on what it actually does — its own description of its product — rather than on a broad category label. Batch, team size and operating status come from the YC directory and are shown as-is. We do not rank by payment.
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