The extent to which renewables should dominate Australia’s energy grids is a key issue in science and policy. Solar and wind are undoubtedly now the cheapest form of electricity. But limitations on these technologies could undermine the case for a renewable-only electricity mix.
The challenges presented by solar and wind generators are real. They are essentially variable, producing electricity only when the sun is shining and the wind is blowing. To ensure reliable energy supplies, grids dominated by renewables need “booster” capacity: backup technology that can supply electricity on demand.
Some, including the Albanian government, argue that gas generators are needed to fill the gap. Others, like the Coalition, say renewables can’t “keep the lights on” at all and Australia should pursue nuclear power instead.
But a new way to power the world’s electricity grids is developing rapidly: sodium-ion batteries. This emerging energy storage technology could be a game changer – enabling our grids to run on 100% renewable resources.
Sodium-ion batteries: the pros and cons
Energy storage collects excess energy generated from renewable sources, stores and releases it on demand to help ensure a reliable supply. Such facilities offer short-term or long-term storage (more than 100 hours).
Currently, lithium-ion batteries are the main storage technology, but they are best for short-term storage. Sodium-ion batteries are now almost ready to fill the long-term storage gap.
As the name suggests, sodium-ion batteries contain sodium (symbol Na), an element found in salt. The technology involves the movement of sodium ions between the positive and negative poles, which creates a charge.
The technology used in sodium-ion batteries is similar to that of lithium-ion batteries. In fact, as others have pointed out, factories currently making lithium batteries could easily and cheaply switch to sodium batteries.
And sodium is a much more abundant material than lithium, and potentially cheaper to mine.
Some types of lithium mining require a lot of water and energy and have led to local pollution, such as in the alpine lakes of South America. Contamination issues are far fewer, however, in Australian lithium.
Recycling and disposal of lithium batteries is challenging – although much easier than recycling carbon from fossil fuels.
In terms of performance, sodium batteries hold their charge for much longer than lithium batteries.
But as with any technology, sodium-ion batteries present challenges. Sodium ions are larger and heavier than lithium ions. This means that batteries are less energy dense than their lithium counterparts, and thus require more space and material to store the same amount of charge.
However, this is improving. According to one analysis, the energy density of sodium-based batteries in 2022 was equal to that of low-end lithium-ion batteries a decade ago.
And ongoing research and development means their energy density continues to increase.
Exit to the market
As with all promising technologies, a key question for sodium-ion batteries is when they can be widely commercialized.
To answer this, we can look at the latest analysis based on a method developed by the Massachusetts Institute of Technology. It suggests that sodium-ion batteries are becoming increasingly cost-competitive – and could thus enter the global market as early as 2027.
The analysis suggested that sodium-ion batteries would soon match the cost of using gas energy as a boost energy source.
Similarly, an assessment by the United States Department of Energy in September last year found that sodium-ion batteries are “expected to take a significant share of the market by 2030”.
He said the technology could become a competitive replacement for lead-acid or lithium-iron phosphate batteries in both small-scale vehicle electrification and “behind-the-meter” applications such as supporting home solar panel systems.
The analysis found that current and planned production of sodium-ion batteries was concentrated in China and Europe, and several major battery manufacturers “were planning large-scale production facilities in the near future.”
They include Chinese electric vehicle company BYD, which has reportedly started building a sodium-ion battery facility in Xuzhou.
In Australia, UK-based battery company Faradion installed small stationary modules in Victoria’s Yarra Valley in 2022.
Keeping our options open
A recent plan from the Australian Energy Market Operator (AEMO) suggests that coal-fired power will be phased out by 2035. But the plan suggests that a significant amount of gas will remain on the grid.
The AEMO analysis did not consider the potential of long-term energy storage to compete with gas. However, the development of technologies such as sodium ion batteries suggests that we should question AEMO’s assumed need for gas in the future.
Disruptive innovations grow quickly and exponentially. We only have to look at the annual growth rates for existing clean energy technologies such as solar (29%), wind (14%), electric vehicles (54%) and battery storage (52%).
The Climate Change Authority is currently assessing Australia’s potential technology transition and emissions pathways as we move towards net zero emissions by 2050. Within the scope of the review is to examine which technologies can be used in each sector to support reducing emissions.
The potential of sodium-ion batteries suggests that policies put forward by the authority should not block polluting options for the electricity sector, such as gas-fired power. Cleaner alternatives are likely to be commercial in a few years – and the stability of our climate depends on planning for them.
Peter Newman, Professor of Sustainability, Curtin University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
