As Queensland progresses toward its renewable energy target, grid-scale battery storage will become increasingly important for the reliability of the energy system. 

Here’s what you need to know about how batteries work, and how they can help to firm the grid as the way we generate energy evolves.  

How do batteries store energy? 

A‌ ‌fundamental‌ ‌problem‌ ‌with‌ ‌electricity‌ ‌is‌ ‌that‌ ‌it‌ ‌cannot‌ ‌be‌ stored.‌ But ‌batteries‌ ‌are‌ ‌a‌ ‌way‌ ‌of‌ ‌getting‌ ‌around‌ ‌this‌ ‌problem‌ ‌–‌ ‌they‌ ‌use chemicals to absorb and release energy on demand, through a process known as electrochemistry. 

Batteries ‌consist ‌of‌ ‌three‌ ‌main‌ ‌components‌ ‌–‌ ‌two‌ ‌electrodes,‌ ‌called‌ ‌the‌ ‌anode‌ and‌ ‌the‌ ‌cathode (positive),‌ ‌and‌ ‌a‌ ‌chemical‌ ‌solution‌ ‌called‌ ‌an‌ ‌electrolyte‌ ‌that‌ ‌allows for the flow of electrical charge between them. 

If‌ ‌a‌ ‌battery‌ ‌is‌ ‌disposable,‌ ‌this‌ ‌process‌ ‌only‌ ‌works‌ ‌in‌ ‌one‌ ‌direction‌ ‌–‌ ‌electrons‌ ‌flow‌ ‌from‌ ‌the‌ ‌anode‌ (referred to as the negative electrode) ‌to‌ ‌the‌ ‌cathode (referred to as the positive electrode), ‌transforming‌ ‌chemical‌ ‌energy‌ ‌to‌ ‌electrical‌ ‌energy.‌ Eventually,‌ ‌as‌ ‌the‌ ‌chemical‌ ‌potential‌ ‌of‌ ‌both‌ ‌electrodes‌ ‌wears‌ ‌down,‌ ‌so‌ ‌will‌ ‌the‌ ‌disposable‌ ‌battery.‌ ‌ ‌

In‌ ‌rechargeable‌ ‌batteries,‌ ‌however,‌ ‌this‌ ‌process‌ ‌can‌ ‌be‌ ‌reversed.‌ ‌As‌ ‌electrical‌ ‌energy‌ ‌from‌ ‌an‌ ‌outside‌ ‌source‌ ‌–‌ ‌like‌ ‌a‌ ‌charger‌ ‌that‌ ‌you‌ ‌plug‌ ‌into‌ ‌your‌ ‌wall‌ ‌–‌ ‌is‌ ‌applied‌ ‌to‌ ‌the‌ ‌chemical‌ ‌system‌ ‌and‌ ‌moves‌ ‌electrons‌ ‌from‌ ‌the‌ ‌cathode‌ ‌to‌ ‌the‌ ‌anode,‌ ‌it‌ ‌restores‌ ‌the‌ ‌battery’s‌ ‌charge.‌ ‌

This‌ ‌process‌ ‌greatly‌ ‌enhances‌ ‌the‌ ‌battery’s‌ ‌lifespan,‌ ‌but‌ every‌ ‌charge‌ ‌cycle‌ ‌degrades‌ ‌the‌ ‌electrodes‌ ‌further,‌ ‌until‌ ‌eventually,‌ ‌even‌ ‌a‌ ‌rechargeable‌ ‌battery‌ ‌will‌ ‌stop‌ ‌working.‌ ‌ ‌ ‌

There are various types of batteries, but today,‌ ‌lithium‌-ion‌ ‌batteries‌ ‌are‌ ‌most‌ ‌commonly‌ ‌used‌ ‌for‌ ‌storing‌ ‌electricity.‌ Because lithium is the lightest metal, and has the highest electrode potential, lithium-ion batteries generally offer superior energy-to-weight performance.

Originally used primarily for mobile applications like smart phones, tablets and laptops, lithium-ion batteries made their way into electric cars in 2008, with the production of the first Tesla Roadster. They’ve since become ubiquitous, used in virtually all electric car makes and models and countless other devices. 

This means that lithium-ion batteries are being manufactured in ever-increasing numbers at ever-diminishing prices. This has made these batteries increasingly economical to be used by homes and businesses as part of battery energy storage systems (BESS), which store energy generated by solar panels during periods of high supply and/or low usage, so that energy can be used when it’s needed. 

When a large number of batteries are installed together and connected to the electricity grid to serve as a generator, this becomes a grid-scale BESS – often simply referred to as a grid-scale battery. 

The‌ ‌world’s‌ ‌first‌ ‌grid-scale‌ ‌lithium‌-ion‌ ‌battery‌ ‌was‌ ‌commissioned‌ ‌in‌ ‌California‌ ‌in‌ ‌2012.‌ ‌Batteries‌ ‌are‌ ‌measured‌ ‌in‌ ‌megawatts‌ ‌(MW)‌ ‌and‌ ‌megawatt‌ ‌hours‌ ‌(MWh)‌ ‌–‌ ‌the‌ ‌Californian‌ ‌battery‌ ‌provided‌ ‌1.25‌ ‌MWh‌ ‌of‌ ‌energy‌ ‌storage,‌ ‌capable‌ ‌of‌ ‌discharge‌ ‌at‌ ‌5‌ ‌MW,‌ ‌which‌ ‌meant‌ ‌it‌ ‌could‌ ‌run‌ ‌at‌ ‌full‌ ‌power‌ ‌for‌ ‌15‌ ‌minutes.‌ ‌ ‌

Today,‌ ‌grid-scale‌ lithium-ion batteries‌ ‌are‌ ‌much‌ ‌larger‌ ‌and‌ ‌increasingly‌ ‌common.‌ ‌The largest in Australia – for now – is the Victorian Big Battery near Geelong, which provides 450 MWh of storage and can discharge at 300 MW, enough to power roughly one million homes for half an hour.  

Flow batteries are a relatively new entrant in this market. Flow batteries separate positively charged electrolyte and negatively charged electrolyte into two tanks, with a conductive membrane between them – to scale up the battery and store more energy, you can swap out the tanks for bigger ones, without replacing the membrane. 

Flow batteries tend to have much less power density than lithium-ion batteries. They can deliver a consistent amount of energy for a longer period of time than lithium-ion batteries, but lithium-ion batteries are better suited to providing larger bursts of energy for shorter periods of time. 

How can batteries support the reliability of the energy grid? 

Renewable energy sources, such as wind and solar power, are variable in nature, because they’re dependent on the weather. 

In order for the energy grid to remain reliable and resilient when the sun isn’t shining and the wind isn’t blowing, these variable renewable energy sources need to be ‘firmed’ with dispatchable energy sources that can be called upon as needed to cover shortfalls in supply. 

Firming and storage can take several forms. Long-duration storage, such as pumped hydro energy storage (PHES), can discharge stored energy for 24 hours or more at a time, and play a key role in managing extended renewable droughts. 

Batteries, however, are ideal for providing intra-day storage – absorbing renewable energy generated throughout the day that would otherwise not be used, storing it, and discharging it minutes or hours later to meet demand. This has the effect of smoothing the variable output from renewable generators, improving system reliability and minimising the fluctuation of electricity prices. 

That’s why batteries are a key component of the Queensland Energy and Jobs Plan. 

Under the Energy and Jobs Plan, it’s expected that renewable resources will produce 70 per cent of Queensland’s power by 2032, and 80 per cent by 2035. (This is a significant increase – at the time the Plan was announced in 2022, only 21.4 per cent of Queensland’s electricity came from renewables.) 

Based on the Australian Energy Market Operator’s demand forecasts and energy market modelling, the Queensland SuperGrid Infrastructure Blueprint projects the state will require 3 GW of grid-scale intra-day storage, such as batteries, to maintain grid stability.

(This is in addition to 6 GW of long duration storage, such as the aforementioned pumped hydro; 3 GW of new low-to-zero emission gas-fuelled generation, to provide additional capacity at times of peak demand; and the existing transmission interconnectors between Queensland and other states, which can transfer additional generation to Queensland when needed.) 

To that end, the Plan commits $500 million to grid-scale and community battery projects across the state that maximise local content, creating opportunities for local manufacturing. 

Independent modelling projects that the additional renewable energy and storage under the Plan will help to protect Queensland from global price shocks, and lead to the average annual bill for a household being $150 lower in 2032 than it would be without a Plan. 

What’s next?

The Queensland Government has released the Queensland Battery Industry Strategy 2024-2029, which highlights opportunities to further Queensland’s capabilities in the refining and production of advanced battery materials, as well as cell manufacture, pack assembly, installation and recycling. 

The Strategy outlines actions that will target $570 million in investment over the next five years, including: 

1. 1.

   $275 million to support the industry to innovate and commercialise battery technologies, including $105 million to plan and establish the Australian Battery Industrialisation Centre in Queensland.

2. 2.

   $92.2 million to drive battery investment and supply chain growth, including an $80 million industry grant program.

3. 3.

   $202.5 million to position Queensland as the preferred supplier of advanced materials and batteries to domestic and international markets, including $5 million to establish Batteries Queensland, which will connect industry with relevant government agencies and support.

Stanwell, Queensland’s largest energy supplier, already has two grid-scale battery projects in its renewable energy pipeline – the proposed Southern Renewable Energy Zone battery project, located near Tarong Power Station, and Central Renewable Energy Zone battery project, located near Stanwell Power Station. 

The Queensland Energy and Jobs Plan also calls for the development of a two-way energy market that effectively integrates home batteries – as well as electric vehicles and rooftop solar systems – into the energy grid. 

Developing a smart, interconnected grid that supports the efficient orchestration of energy flow from millions of inter-connected devices – as opposed to the one-way flow from large-scale generators to energy customers that has been the norm – will require new technologies, new data requirements and regulatory reform. 

The Energy and Jobs Plan commits to 100 per cent penetration of smart meters by 2030, which will help to provide the data required to manage a two-way market, as the first step towards the effective integration of these customer energy resources. 

Ultimately, batteries alone won’t provide all of the storage and firming the grid needs – but alongside other energy storage and firming technologies, they will allow for greater deployment of renewable resources, and help to ensure the continued reliability of the grid for homes and businesses.