NZ startup EnergyBank:
‘we can help decarbonise 42 countries’

New deep tech involves lowering and raising giant concrete masses deep in the ocean.

The following includes excerpts by Nicola Shepheard (NBR)


Kiwi startup EnergyBank have raised $2.7 million in an oversubscribed seed round led by Icehouse Ventures to develop a new technology for storing energy for medium to long durations, which it claims is better than pumped hydro or lithium ion batteries

Founders of EnergyBank, which is pre-revenue but has received letters of intent worth tens of millions per year, claim their deep ocean technology could enable the decarbonisation of electricity grids in 42 countries within 30 to 40 years, bringing clean energy to regions from the Asia Pacific to the Red Sea and the West Coast of Africa.

Energy Bank calls its tech Deep Ocean Gravitational Energy Storage (DOGES). The system works by taking surplus renewable energy from the grid on land, or an offshore wind farm, and using it to drive a motor that lifts giant weights from the ocean floor to just below the surface, storing the energy as gravitational potential energy. When that energy is needed, the weights are lowered, which drives the motor and the energy flows back into the grid in reverse.

Each weight travels between 4km and 8km vertically back and forth between the ocean floor and surface.

EnergyBank co-founder and chief executive Tim Hawkey said the process requires no land, has little accident risk, and is lower-cost, more scalable and more environmentally friendly than alternatives.

The inventors were careful to select material with low environmental impact and carbon profile.

The weights are made from concrete which lasts many years in the marine environment – there are concrete structures from ancient Rome that now have coral reefs growing on them – and is lowered at a maximum speed of 30cm per second.

“It’s basically [like] a big iceberg, whale and dolphins are manoeuvrable enough to get out of the way.”

The company is looking at using an iron ore aggregate with ore sourced from outback Australia.
It has built costing models of the full-scale concept and crafted a scale prototype out of a piece of farm pipe and electric skateboard motors.


Hawkey believes his technology has edge over the other main large scale storage solution pumped hydro for multiple reasons;

  • The company are looking at creating standardised units [which give] the same advantages you get from a lithium ion battery cells but much larger and much cheaper. You can just mass produce a standardised unit and add it as needed to an installation.
  • Sizing pumped hydro schemes for an unknown future need is another big challenge, and the one-off dam build requires huge capital expenditure. By his best estimates, the EnergyBank technology could store energy at about one-fifth of the price of pumped hydro or lithium ion batteries.


The seed round, led by Icehouse Ventures, also included Blackbird Ventures, Outset Ventures, US-based deep-tech fund Promus Ventures, Canadian fund Version One, and young New Zealand fund Nuance Connected Capital.

EnergyBank will use the $2.7m to build the team (currently is hiring for three roles), continue proving the concept’s all-round viability and scalability, and developing customer relationships:

The Vision

The vision is for EnergyBank to mass-produce floating energy storage units and deploy them off the coasts of 42 countries worldwide. Each unit will store up to 10GWh of energy (about $10 billion worth of Li-Ion).

“In conjunction with floating offshore wind, they will enable the complete economic decarbonisation of economies like Japan, Taiwan and Australia.”

He said he believed both technology and behavioural change would be needed to stave off the worst of climate.


21 October 2021


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