Future of Renewables: Battery Energy Storage Systems
Battery Powered World?
Years ago working on renewables transactions as a young curious analyst, I had questions. One of which is:
What happens to the electricity that was generated by all the solar and wind plants that are not consumed?
Short answer: It remains unused.
I never knew the answer then or never really bothered enough to find out.
But what I have learned over the years is that in most countries, electricity demand and supply in the national grid is generally managed and balanced such that this scenario of “spare” electricity rarely happens.
Simply because the grid cannot store large amounts of electricity.
For now that is.
Existing power plants utilising fossil fuels are slowly being phased out while renewable energy is clearly taking its place to be the most dominant and affordable source of electricity.
This renewable energy is generally produced by harnessing solar and wind power from nature.
But there are pitfalls to solar and wind power.
Probably the largest one? Solar and wind power are intermittent sources of energy.
Solar power can only be produced when the sun is up and shining while wind power can only be produced when the wind is blowing.
What happens when it is night time and if the wind is not blowing?
No electricity unfortunately.
Now then, what has batteries got to do with this?
Battery Energy Storage Systems (“BESS”) are essentially giant batteries that, amongst other things, offer a great solution to the problem of intermittency.
They can store excess electricity and in doing so, allows for time-shifting of renewable energy to periods of increased demand.
Word of the day: Time-shift
This means that when there is so much sunlight (especially in the daytime) and the solar farms are producing way too much electricity for existing needs, some of it can be used to charge up the batteries (ie. storing the energy).
At night, when there is no sunlight and no production from the solar plants, the batteries can be discharged to supply the electricity to consumers.
The above concept applies for wind farms as well.
Essentially, we are able to time-shift some of the generated energy to a period where it is needed the most.
Other key benefits that BESS provides include:
- Stabilisation of grid frequency (grid frequency too high/low = bad!)
- Contingency/backup power reserve
- Black-start (after a system blackout)
- Allows governments to defer expensive and lengthy upgrades to transmission networks
BESS are important for renewables to fully replace fossil fuels and become the main source of energy.
Wanna hear a story (or two) about how batteries kept the lights on?
25 August 2018.
Lightning struck.
Took out two circuits in a main interconnector between New South Wales and Queensland, Australia.
Grid frequency immediately plunged and within two seconds, the Queensland grid became islanded (meaning: cut off from the main grid).
In another few seconds after, South Australia was islanded too.
The coal and gas plants were slow to respond and could not adjust its output to deal with the changes in frequency.
The Hornsdale battery in South Australia sprung into action by instantaneously (literally milliseconds) supporting the frequency of the grid for the next 25 minutes until the backup thermal plants could come online.
What did this mean?
Households in South Australia barely noticed this event. For the households in Queensland and New South Wales? Blackouts.
BESS has time and time again proven itself to be an exceptionally valuable asset in maintaining grid stability
In another incident, a mini-tornado in January 2020 brought down an interconnector between the states of South Australia and Victoria.
South Australia was islanded for 18 days. No problem.
The batteries in the state took on the roles of maintaining the grid’s reliability, once against proving the value of BESS.
What is the future looking like for BESS?
The current dominant technology is lithium-ion but there are also other battery chemistries that are available or currently being researched further.
This includes: lead-acid, redox flow, and molten salt.
With more viable technologies and additional economies of scale, I fully expect BESS to achieve a much larger and accelerated rollout over the rest of this decade.
There are a few issues that obviously needs to be worked out, including safety (a large fire happened recently at the largest BESS in Australia) but it is undeniable that BESS is here to stay and these issues will be worked out sooner, rather later.
BESS will grow together with the megatrend of renewables
This article is part of a series on the future of renewable energy. If you are interested in finding out more, do feel free to check out the other articles in the series.
