Energy storage is at the tipping point for reframing renewable energy as a genuine zero-carbon replacement for today’s fossil-fuelled energy grid, argues Adelaide technology entrepreneur Simon Hackett.
Anyone who pays attention knows that burning coal and other fossil fuels to generate electricity contributes in a major way to atmospheric carbon dioxide and particulate pollution, a change-driving activity that presents a substantial medium-term threat to human habitation of the planet.
However, high-density, generator-scale wind, solar, and concentrated solar power (CSP) facilities, in addition to rooftop solar installations, are now becoming so widespread as to challenge the management and operation of the world’s power grids.
In some countries, solar or wind peak periods produce levels of renewable-energy generation that actually exceed total grid energy demand – “crossover” periods that increase in frequency and duration as renewable-energy deployments accelerate.
As well as peaks, these crossover periods produce problems when clouds occlude solar panel or CSP arrays because fossil-fuelled baseload power generators may not spin up fast enough to fill the gap. This leads to pathological outcomes, such as the need to burn more coal in parallel to operating renewables, just in case clouds obscure the sun suddenly.
The impact of this large influx of solar-derived energy during daytime solar peak times creates an energy supply and consumption pattern known as a “duck curve,” due to its shape, described further here.
Unless the impacts of the duck curve are addressed, renewable-energy sources will start to do more harm than good to the existing energy grid.
Turning renewable energy generation into a baseload power source
To get rid of the fossil fuel-burning baseload power generators, we must find a way to time-shift the flow of renewable-energy generation at the same global scale that we are deploying renewable-generation capacity.
The presence of grid-scale energy storage will allow us to efficiently match the shape of the electrical-energy supply curve from renewable sources to the shape of the demand curve on a 24/7 basis.
The general solution (and opportunity) seems best addressed by the manufacture and deployment of grid-scale batteries.
It seems clear that the world can do this. We have done things this big before.
But supply follows demand. While keen early adopters have installed battery storage alongside their home solar arrays for years (I put one of these in my own home in 2010), until recently we lacked a lightning rod to reframe energy storage as an attractive proposition to the general population.
Last month, electric carmaker Tesla re-factored its lithium-based vehicle battery packs by redeploying them into a broader energy storage role. Leveraging strong social media mojo for both the Tesla brand and its CEO, Elon Musk, the Powerwall release made a global splash.
Despite being based on conventional lithium-derived battery chemistry, Powerwall has made the concept of electrical energy storage sexy.
Lithium batteries at grid scale
The continuous conversion of intermittent energy sources into baseload power at grid scale is a punishing application for batteries. There are significant challenges inherent in the use of lithium and other “rare-earth”–based battery chemistries in this role.
As its name implies, a rare earth-based battery uses a rare mining commodity to refine for use in energy storage applications. There’s a good argument for expending the finite supply of rare-earth materials, by preference, into applications (such as transport) that require their use.
Lithium batteries are well suited for “power” applications, such as driving electric cars, which require only periodic bursts of high power use, whereas grid-scale power storage require “energy” batteries with the ability to deliver consistent, round-the-clock performance.
Alternative battery approaches
Batteries suitable for grid-scale deployment globally require:
- 100 per cent depth-of-discharge capability without battery degradation or damage.
- Support for continuous duty-cycle operation (not requiring rest between energy cycles, capable of multiple aggregate cycles per day).
- Made from commonly available materials to ensure cost-effective source material supply to global scale.
- Wide operating temperature range without active thermal control.
- Not at risk of thermal runaway or fire if physically damaged or shorted out.
Driven by the huge scale of the resulting opportunity, several companies are now working on new forms of batteries that have most or all of these attributes.
Ambri, led by Professor Donald Sadoway, continues to develop its Ambri Liquid Metal battery to address the grid-scale energy storage and delivery goal. Well-resourced Ambri is moving from the prototype to early field-trial stage, with commercialisation expected in the next few years.
Aquion Energy is another fascinating battery maker. It has chosen to deploy batteries using an absolute winner in the material abundance stakes: seawater! One challenge it faces is very low energy density. A cubic shipping-pallet–sized Aquion module delivering a nominal 29 kWh weighs in at 1,440kg, much heavier and larger for a given energy capacity than even lead-acid batteries.
Redflow makes a different type of battery, called a flow battery:
(Source: University of British Columbia)
What makes a flow battery special is its ability to be fully charged and then shut down for months or even years, with practically all stored power available when restarted; the ability to be discharged to zero volts without suffering damage; extreme hardiness; and support for repeated 100 per cent charge / discharge cycles. The harder one works a flow battery in the discharge cycle, the better!
After discovering Brisbane-based Redflow several years ago while searching for innovative companies working in energy storage, I was so impressed that I invested in the company and later joined its board of directors.
The Redflow battery has emerged successfully from more than a decade of research and commercialisation development. The core Redflow product line is the zinc bromine module (ZBM). The latest version – ZBM3 – is an 11 kWh storage device weighing about 240 kg.
The grid-scale Redflow Large Scale Battery (LSB) integrates 60 ZBM3 modules into a six-metre shipping container form factor to deliver a nominal 660 kWh of storage. It has high internal redundancy and automatically works around the failure of any internal ZBM3 modules.
One of the challenges with new battery companies is figuring out whether they really make batteries that work, that can be purchased for real applications – or whether they’re still “vapourware,” in commercial terms.
The Redflow ZBM product line commenced commercial production earlier this year at Flextronics in Mexico, with batteries now being delivered into integration projects in key customer sites around the world. The first production Redflow LSB is being built now for installation at my multi-tenanted office complex in Kent Town.
I intend to integrate the LSB with our existing rooftop solar deployment to time-shift grid-sourced energy (recharging the battery overnight and delivering energy into the office during the day).
Once our existing solar deployment is expanded, we plan to take the whole office complex “off grid,” with our existing grid supply becoming the backup energy path rather than the primary one.
Field demonstrations of LSB units with grid-energy companies in grid-levelling applications are in negotiation now and are expected to commence later this year.
I believe that flow batteries are ideally suited to grid-scale “energy” applications, arguably more so than lithium chemistry, because of their distinctive and unique technical characteristics, as already mentioned.
Where to go from here?
To underscore a point Elon Musk made at the Powerwall release event: converting the world energy grid to becoming majority renewable-sourced is now entirely achievable.
But it will take more than just Tesla to do it.
The global-scale task of transforming our electricity supply systems into using renewable energy as the primary generation source is a task that will keep a lot of companies busy for a long time, as they literally change the world.
I believe that, in future, 2015 will be seen as the year that the renewable-energy storage sector hit its inflection point. I can’t wait to see the results of that inflection point taking hold in the world around us.
Simon Hackett is an Adelaide-based technology entrepreneur and founder of Internode.
This article is based on a longer letter written for subscribers of the Strategic News Service newsletter. The original letter may be found here.
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