A WA gold mine ran for four days straight with the diesel and gas engines switched off
Bellevue Gold’s off-grid plant in Western Australia reported a record stretch of 100% renewable power with the fossil engines parked. The lesson for a homestead is the same as the lesson for a mine: size the duty cycle, then name the days the engines still wake up.
September 2026 · Bellevue, WA101 consecutive hours, engines off
In the December 2025 quarter — the stretch around November — Bellevue Gold reported 101 consecutive hours of 100% renewable power at its off-grid gold mine, with the diesel and gas engines switched off. RenewEconomy and Australian Mining both carried the company’s ASX note. The previous published mark on the same plant was 84 hours.
Call that run engines off (sometimes hydrocarbons-off): the generators stopped, and the site ran on wind, solar and the battery only. The site is islanded — running disconnected from the main electricity grid, making and managing its own power.
That is the design end-game customers ask about. Not “zero diesel forever.” Long stretches of diesel hours saved when the renewable plant is sized to the duty cycle.
A hybrid, not a solar farm with a sticker
The plant is a hybrid: mixing two or more power sources — here solar, wind, a battery, plus diesel and gas kept as backup — so the site stays up when the sun and wind are not enough. Average site load sits around 12 MW.
About 27 MW
Daytime bulk. Stronger into summer, thinner on a mid-winter overcast day.
About 24 MW
Turbines only started production in May 2025. Bellevue flagged summer as the windier season too.
15 MW / 30 MWh
Power rate of 15 megawatts. Stored energy of 30 megawatt-hours. About two hours at nameplate.
Diesel + gas / LNG
About 9 MW diesel and 15 MW gas kept in reserve. LNG here means liquefied natural gas, the other backup fuel.
Translate the industry line
Industry copy loves a short stack of initials. Here is the same story in plain words.
Rate versus tank
A megawatt is the power rate — how hard the plant can push. A megawatt-hour is energy stored or used over time. Think hose pressure versus the size of the tank.
Keep the lights even
Making solar (or wind) power steady and usable when the sun dips or a big load kicks in — usually with a battery, and sometimes a backup generator.
Hours the genset sits quiet
Cutting how many hours (or litres) the diesel generator runs by covering load with solar and batteries first.
Renewable penetration is the share of site electricity that came from solar and wind, not diesel or gas, over a period. Bellevue said that share sat around 88% for the quarter, toward the top of its 80–90% target. The company has positioned the project as among Australia’s most renewably powered off-grid mines.
A two-hour battery, a four-day run
The battery on its own is not a four-day tank. At 15 MW nameplate it holds about two hours. Multi-day engines-off works because the wind and solar keep topping the battery up. Firming is the battery’s day job. Duration of the engines-off streak is a weather-and-mix story, not a “buy a week of mine load in boxes” story.
Mostly off diesel. Not never diesel.
Treat the published run as about four days of continuous engines-off in good conditions at this scale — 101 hours is four days and five hours. Quarterly renewables sat in the high-80% range, not 100% year-round.
Bellevue told the market the December quarter would take further benefit from solar and wind heading into summer, and that this would cut diesel and LNG use. Summer-favourable wind and solar is a real climate fact on that site. It is also the opposite of a mid-winter homestead on the ranges, where the days are short and the evening load is the whole story.
The design question we ask on every job: what does “mostly off diesel” look like in a real winter versus a real summer duty cycle? Bellevue’s answer is a hybrid sized so the engines can sleep for days when the mix is kind, then wake for the thin weeks. A homestead uses the same drawing. The zeros on the nameplate change.
Same pattern on a farm or a shed
You do not buy 27 MW of panels for a house. You do buy the idea: solar and wind (or just solar) first, a battery that firms the evening and the cloud gap, diesel as the spare tyre rather than the engine.
Fill and run
Cover the load while the sun (and wind) are up. Push surplus into the battery.
Ride the pack
The battery is for hours, not a fortnight. Size it to the night you actually live.
Name the backup
Diesel, gas, or the grid if you have one. Write the days you will use it. Do not pretend they are zero.
That is the same conversation we have on a Northern Rivers shed and a Western Downs hall. See the Dalby sizing note for the winter-design-day version of the same rule, written at data-centre scale.
What we leaned on
Public figures in this piece come from Bellevue’s December 2025 quarterly activities report and the coverage that followed. We did not invent a fourth turbine or a week-long battery.
- RenewEconomy, 28 November 2025 — 101 consecutive hours with engines off
- Australian Mining — record renewable energy and high-grade growth
- Bellevue ASX December 2025 Quarterly Activities Report (company filing cited in that coverage)
A town, a dairy, then your load
A remote NT community ran the solar-plus-modest-battery play and cut bills around 70% — read Marlinja’s First Nations microgrid. A Gippsland dairy used a dam as the storage instead of a big battery — read Wilandra Farms solar irrigation. More notes live on Learn.
Sized for the duty cycle you actually live
We design hybrid plants for people who care what happens after three grey days — homes, farms, and commercial loads. If you want a system sized that way, talk to The Off Grid Shop.
Prefer to talk it through? Call or text 0483 927 257 — Lismore HQ, local voices.