TECHNOLOGY

ENERGY STORAGE EXPLAINED

Energy storage will play a critical role in decarbonising the electricity system and reducing global carbon emissions.

 

Renewable sources of generation rely on the elements, such as wind and sunshine. When the wind isn’t blowing and the sun isn’t shining, energy storage will ensure Australians can still turn their lights on at a reasonable price. Rather than shifting energy between places – energy storage allows us to shift energy between times.

 

AEMO has forecast that the National Electricity Market (NEM) will require 46GW/640GWh of dispatchable energy storage in all its forms by 2050. At North Harbour Clean Energy, we are focussing on operationally proven storage technologies.

A mismatch between energy demand and supply across a given day

PUMPED HYDRO ENERGY STORAGE (PHES)

Pumped hydro has the lowest cost of storage out of all long-duration energy storage technologies due to its scalability and extended lifetime. It is a proven technology that has existed for almost 100 years and accounts for over 94% of large-scale global energy storage.

 

Pumped hydro operates like a battery, generating energy during peak demand and storing energy during low demand.

 

Hydropower energy is generated by releasing water downhill from the upper reservoir through a turbine into a lower reservoir. Pumped hydro operates on the same principle, and simply uses energy to pump the water back uphill from the lower reservoir to the upper reservoir.

Cross-section of a standard PHES system

ADVANTAGES OF PUMPED HYDRO

Lowest cost due to lifetime and scale
Longest service life for energy storage
Large scale and long duration 
Sustainable, with recycling of water
Mature technology, utilised for 100 years
Multi-functional

LARGE-SCALE VANADIUM REDOX FLOW BATTERIES (VRFB) 

While pumped hydro is the cheapest form of storage, it is site constrained. The technology requires significant height differential over short distances. In comparison, batteries can be deployed anywhere.

 

VRFBs are a proven technology. The technology was first developed in the 1980s by North Harbour Clean Energy’s trusted advisor, Maria Skyllas-Kazacos, at UNSW.

 

VRFBs use vanadium ions as charge carriers. Vanadium electrolyte is stored in two external tanks and pumped through the battery cell generating a charge. The battery uses vanadium’s ability to exist in solution in four different oxidation states to make a battery with a single electroactive element instead of two, avoiding cross-contamination and preventing degradation over time.

 

When coupled with a renewable energy source, VRFB’s produce 78% less CO2 than other batteries.

Internal chemistry of VRFB

ADVANTAGES OF VANADIUM BATTERIES

Less than 1% capacity degradation
Scalable from 1MW to 200MW
(
with options for 4-10 hours of energy storage)
25 year design life – unlimited cycles 
100% depth of discharge
Low life-cycle environmental footprint
Non-flammable
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