Mercury’s $1 Billion Geothermal Expansion Signals a New Era for New Zealand’s Renewable Energy Future By: Robert Buluma Mercury Doubles Down on Geothermal Power New Zealand’s renewable energy transition has entered a bold new chapter after Mercury announced plans to significantly scale its geothermal platform with a potential investment of up to $1 billion. The announcement marks one of the country’s most ambitious geothermal expansion strategies in recent years and reinforces geothermal energy’s growing role as a reliable, baseload renewable power source capable of supporting future electricity demand. Mercury revealed that it will immediately commit NZ$75 million toward geothermal appraisal drilling at two major projects located near Taupō — Ngā Tamariki and Rotokawa. These developments could collectively generate an additional 1 terawatt-hour (TWh) of electricity annually, enough to power approximately 125,000 more homes across New Zealand. The projects are expected to t...
China Just Built the World’s Cleanest Large-Scale Geothermal Heating System – And Barely Anyone Noticed
China Just Quietly Built One of the Greenest Heating Systems on Earth – And Hardly Anyone Noticed
By: Robert Buluma
In a quiet corner of Shaanxi Province, something remarkable just happened.
On an ordinary day in late 2025, nine deep geothermal wells in Qishan County, Baoji City, began pumping clean heat from 2,800 meters beneath the Earth’s surface into thousands of homes. No smoke. No coal. No water extracted from the ground and no wastewater discharged back into it.
This is China’s first large-scale mid-deep geothermal closed-loop district heating project, and it might be one of the most under-reported green energy milestones of the decade.
The Numbers Are Staggering
9 geothermal wells (drilled to 2,800–3,000 m)
100% closed-loop heat exchange – zero fluid leaves or enters the rock formation
Supplies central heating to the entire southern district of Qishan County
Annual savings: 12,000 tons of standard coal
Annual CO₂ reduction: 31,000 tons
- Energy mix:
– 50% mid-deep geothermal (base load)
– 30% wastewater-source heat pumps
– 20% gas boilers (peak shaving & backup only)
That 20% gas backup is the clever part. Instead of relying on coal boilers for the coldest days (the traditional Chinese approach), they use a small amount of gas only when absolutely necessary. The rest of the year, the system runs almost entirely on heat pulled silently from deep hot rock and urban wastewater.
### Why This Is a Really Big Deal
1. It ends decades of no central heating south of the Qinling-Huaihe Line
For historical and climatic reasons, almost everything south of that imaginary line across China had no district heating – people shivered with electric heaters or burned coal stoves indoors. This single project proves that clean, reliable central heating is possible even in “non-heating” zones.
2. Closed-loop mid-deep geothermal is still extremely rare at city scale
Most geothermal district heating worldwide is either shallow groundwater systems or enhanced geothermal systems (EGS) that fracture rock and pump water through it. China just demonstrated a third way: drill deep, insert a giant coaxial heat exchanger, pump a working fluid down and back up in a completely sealed loop, and pull steady heat (120–140 °C) without ever touching the reservoir fluid. Zero water consumption, zero induced seismicity risk, infinite recharge.
3. They optimized the hard way and saved money doing it
The original plan called for 13 wells. Through better reservoir modeling and engineering, the team delivered the same heating capacity with only 9 wells plus two large wastewater heat pumps. Lower capex, lower risk, same warmth.
### A Blueprint for the Rest of the Planet
Northern China already has the world’s largest district heating networks (most still coal-fired). If even a fraction of those systems switch to this hybrid deep-geothermal + wastewater heat pump model, the carbon savings would be measured in tens of millions of tons per year.
And the technology isn’t exotic anymore. Chinese drilling companies now routinely go beyond 3,000 m for oil and gas; repurposing that capability for heat is straightforward. Add readily available large-scale heat pumps and a dash of gas for peak shaving, and you have a template that cold cities from Seoul to Chicago could copy.
### Final Thought
While the world argues about wind versus solar versus nuclear, a county in Shaanxi Province just flipped the switch on a heating system that:
- runs almost entirely on waste heat and deep Earth heat
- cuts coal use by the equivalent of 12,000 tons a year
- keeps people warm without poisoning the air
And they did it without fanfare, without international press tours, without calling it “net-zero demonstration project number 387.”
They just built it. And it works.
That’s how the energy transition actually happens – one ridiculously practical, boringly reliable project at a time.
Qishan County now has the cleanest large-scale heating system south of Beijing.
The rest of the world should probably pay attention.
Source : zhongpeng-wang
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