One of the simplest solutions to our intermittency problem is storage.
This is likely no surprise, as battery storage is now commonplace, with figures from the IEA showing an 8-fold increase in capacity since the turn of the decade:
Graph per IEA1
Commercial and domestic renewable generation assets alike will often be paired with a battery storage solution, allowing surplus energy to be stored, and released at a time when demand exceeds generation.
The energy storage market is currently dominated by Lithium-ion based batteries – a well-established technology which is favoured due to its energy efficiency and low-cost (which continues to reduce over time).
However, Lithium-ion batteries are not without their problems.
Whilst their properties are ideal for smaller scale storage (behind-the-meter, EVs), proper safety measures are required when using Lithium-ion batteries on a more significant scale. They are susceptible to thermal runaway (overheating) and are inherently flammable, meaning that larger-scale storage operations carry greater risk. This certainly doesn’t prevent their use, however if operating at grid-scale, then additional safety costs will be incurred (which can reduce their cost benefit).
The typical lifespan of Lithium-ion batteries is between 5-10 years, depending on their size, and how frequently/completely they are discharged. Given that solar panels and wind turbines have a lifespan of 20+ years (excluding inverters), a Lithium-ion battery which supports these systems may have to be replaced 2-4 times during that period.
A key factor in improving the longevity of a Lithium-ion battery is its ability to be recycled. Although many statistics paint a dim picture of battery recycling rates, there is an important distinction to be made in terms of “collection rate”, as well as the total number of batteries being recycled versus the size of batteries which are being recycled.
Lithium-ion batteries are often built into the device they power, and if the battery is hard to access, it is naturally harder to recycle. If the device is seen as disposable, then its (relatively small) battery will likely be disposed with it.
Larger-scale Lithium-ion batteries should not suffer as much from this problem, for a variety of reasons.
Firstly, larger batteries power larger items, which are typically less disposable (nobody would immediately scrap their car – EV or otherwise – due to a failing battery). These battery units are easier to replace, and therefore easier to recycle.
The modular nature of many large storage systems also enables individual battery units to be replaced (as opposed to the whole system) in the event of any issues, which allows for easier recycling and increased sustainability.
Effective regulation can play a major part. Legislation – such as the EU’s Batteries Regulation – which enforces recycling of assets, with minimum thresholds of recovery when it comes to critical materials, is vital to ensuring the long-term viability of Lithium-ion batteries.
The introduction of “battery passports” will help to ensure compliance and traceability. Under the Batteries Regulation, each battery will soon be digitally labelled, allowing its credentials to be logged and its life cycle to be tracked. Adopting similar legislation would allow the UK to improve the return on its own battery storage assets.
Those regulations aim to tackle what is arguably the biggest obstacle when it comes to the increased adoption of Lithium-ion batteries – their environmental impact.
The production of these batteries (in particular the mining of their raw materials, such as lithium and cobalt) has a significant impact on the environment. The extraction process is energy-intensive, often requiring substantial amounts of water, and can contaminate local ecosystems. Every tonne of lithium mined results in 15 tonnes of CO2 emissions.
So, despite Lithium-ion batteries aiding the use of clean, low-carbon energy, their creation does offset a sizeable chunk of the climate benefit.
From a UK perspective, a reliance on Lithium-ion batteries also raises the matter of energy security, given that the supply of battery metals and cells is held largely overseas – Chile, Australia and China being the largest producers.
So, although Lithium-ion is a clear leader when it comes to efficiency of energy storage, it still faces key challenges in respect of Scalability, Sustainability, and Supply Chains. For any other energy storage technology to be adopted on a widespread basis, it would need to rival the efficiency of Lithium-ion batteries, whilst addressing those same challenges.
In Part 3, we’ll take a look at some of the alternatives, what roles they could serve, and how they stack up against Lithium-ion batteries.
- www.iea.org/data-and-statistics/charts/global-battery-storage-capacity-additions-2010-2023 ↩︎
