You asked about Hydrogen Energy
15 people built something like it. 15 are gone.
That is 100% of the ones whose fate we could settle, against 23% across the whole register.
| Launched | What it was | Today |
|---|---|---|
| 2022-01-01 | First commodity marketplace for hydrogen. · phoenixhydrogen.com | gone |
| 2021-01-01 | Mobile Energy Storage Technology · moxionpower.com | gone |
| 2017-06-01 | Sunfolding builds next generation infrastructure for solar farms. By… · sunfolding.com | gone |
| 2017-06-01 | YCNextDrop NextDrop is the water marketplace for urban India. We connect water… · thenextdrop.com | gone |
| 2019-01-01 | AI driven professional engineering firm · traverse.ai | gone |
| 2022-06-01 | Claim solar incentives with AI · jasmine.energy | gone |
| 2022-01-01 | YCPelm Plaid for utilities · pelm.com | gone |
| 2019-01-01 | We deliver affordable renewable energy direct to customers and are… · getgex.com | gone |
| 2020-06-01 | YCOneKey Find the most profitable sites to build EV charging station · getonekey.io | gone |
| 2023-06-01 | Incentives and financing for energy efficiency upgrades · line.build | gone |
| 2023-06-01 | AI Energy Management · trycardinal.ai | gone |
| 2016-06-01 | Nanoparticle tracers for reservoir characterization during hydraulic… · gtracktechnologies.com | gone |
| 2015-06-01 | Building the lowest-power silicon for embedded deep learning and… · remicro.com | gone |
| 2017-06-01 | YCWATERFX The world's first 100% sustainable water provider (aka alternative… · wacomet.com | gone |
| 2009-01-01 | Sensors and software for energy tracking. Like 'fitbit' for your… · wattvision.com | gone |
How this compares
The register re-probes every domain it holds. Some that answered last month stop answering. We send that list — what went quiet, and what it was — once a month. Nothing else.
How this was made. Show HN entries are every post from 2021 to 2023 with at least five points that linked to its own domain; code hosts and free hosting are excluded, because a repository outlives the effort behind it. Product Hunt entries needed 100 votes — a far higher bar, so they are the promoted top slice rather than a like-for-like sample. Both are judged by asking the domain whether it still answers: gone means it no longer resolves, refuses the connection, serves a parking page, or says plainly that it shut down. An HTTP error is not counted as gone — a server answering 404 is one somebody still pays for, and an audit of 25 gone-calls found two such sites alive with only a moved homepage. Y Combinator entries use the status YC publishes itself, which is why only those can say acquired. Squatted domains — a lapsed name now serving somebody else's site — are not detected, so these figures run slightly low.