EnPot’s technology demonstrated its power flexibility during recent trials in high amperage aluminium cells at the Beihai smelter in China, writes Brydie Burrows*.

Initial trials of the EnPot System at Binzhou Beihai Huihong New Materials smelter have confirmed safe, stable heat balance control in high amperage aluminium cells, marking an important step toward flexible, low-carbon smelting in China and beyond.

Power and aluminium production go hand in hand, regardless of geography. Yet smelters today face challenges from fluctuating electricity prices and supply constraints, ranging from hourly variations to seasonal or annual shortages.

Traditionally, competitive power pricing has been secured through long-term Power Purchase Agreements (PPAs), often based on fixed baseload rates.

However, this model is rapidly changing. As global power grids shift away from fossil fuels and increase their share of variable renewables, smelters are being viewed as assets capable of providing valuable firming and demand-response services to their local grid.

For smelters, the ability to flex production in response to variable power pricing is both an economic and strategic advantage. And now, it is technically possible.

Flexible production

The EnPot system addresses this challenge, enabling controlled modulation of smelter power demand without compromising the stability of the pots. Developed through extensive research and plant trials at the Light Metals Research Centre, University of Auckland, New Zealand, the technology utilises the patented Shell Heat Exchangers (SHEs).

Airflow through the SHE units can be increased or decreased to selectively insulate or cool the pot shell. This enables controlled modulation of smelter power, either on demand or for extended deep modulation operation, providing fine-tuned control of heat extraction and retention.

This approach allows smelters to increase or reduce power consumption, providing flexibility for short-term grid responsiveness or extended periods of load modulation. In addition to operational benefits, such modulation supports broader sustainability goals by enabling smelters to take advantage of low-carbon electricity when it is available and reduce consumption during periods of expensive, high-emission generation.

EnPot has been in commercial operation at Trimet’s Essen smelter, Germany since 2019 and has been demonstrated in Australia, Brazil, Canada, New Zealand and now China.

Its international adoption highlights the demand for technologies that integrate aluminium production with dynamic energy systems. High-amperage demonstration China demonstrates a particularly strong
need for smelters to modulate power consumption. Domestic electricity price volatility, government directives on energy efficiency, and rising global demand for low-carbon aluminium are driving
smelters to explore flexible-load solutions.

In February 2025, EnPot was installed at Binzhou Beihai Huihong New Materials site, or Beihai Smelter, on six large 440kA pots marking the highest amperage application of the technology to date.

The plant trial was designed to validate the technology’s operational range, confirming how much power modulation is achievable while maintaining thermal balance and pot stability. Initial results show excellent heat balance control for substantial shifts in pot heat generation, demonstrating both strong cooling and effective insulation ability on the large cells, while maintaining operational stability and safety.

Design and installation

The EnPot system features stainless steel SHE units mounted on the upper cell sidewalls, to maximise heat transfer control. Each unit is connected via stainless ducting to under-pot suction manifolds
and branch ducts, regulated by airflow control valves.

These branch ducts feed a main suction duct and fan system located outside the potroom, enabling independent control of each pot and balanced airflow for optimised thermal conditions.

The system is extensively instrumented, including pot shell thermocouples, and duct airflow and temperature sensors to provide real-time monitoring for pot safety and control optimisation.

Designed by EnPot and customised for the Beihai pot shell, all pot-side hardware was manufactured in New Zealand and shipped to site.

Each 440kA pot includes 96 SHE units and ten airflow control manifolds, adjustable to fine-tune thermal balance, stabilise operations and support extended power modulation cycles.

Trial performance and insights

During the initial trials, the EnPot team, together with Beihai operators and engineers, explored a range of heat extraction and insulation scenarios.

Key findings include stable operation under high heat generation conditions:

+10% for two weeks
+15% for two weeks
+20% for eight hours, along with multiple short-duration tests in both heating and cooling modes.

The thermal insulation ability of EnPot also extended pot survival during full shutdown tests from four to at least six hours. This is particularly valuable for smelters that experience regular power
blackouts.

Thermal optimisation of pots at normal line current also achieved around 2% power savings without loss of current efficiency, demonstrating clear potential for energy reduction, with further savings
still to be realised.

The trials show the successful, safe, and stable operation of large smelting cells at increased heat generation using EnPot sidewall cooling and heat balance control and optimisation abilities.

These early results provide an important insight into the possibilities available to smelters that take a ‘technology-first’ approach to flexing their production muscle and reinforce that careful management of power remains central to successful, sustainable aluminium operations.

The abilities of EnPot open up this possibility for smelters, which to date has proven difficult for traditional
technologies to manage.

Power modulation is widely becoming accepted as a necessary future goal for smelters around the world, and EnPot is a safe, practical and commercially ready technology to achieve this now.