Australasia, Energy Storage

The hard cell: smart solutions for renewable energy storage

Issue 1 and Volume 16.

The number of utilities interested in renewable power is growing and more large-scale projects are being implemented, but the wider acceptance of these technologies is still being hampered by their intermittent nature. However, the Smart Storage battery concept may hold great promise for the future.

Dr John Wright, CSIRO Energy Transformed National Research Flagship, Australia

It is the perennial problem associated with renewable enery: how can the sun be used to provide energy even when it is not shining? And, likewise, how can wind turbines serve as a power source when the wind isn’t blowing? Storing the energy is the obvious solution, but current battery storage products are considered expensive because of their high initial cost and short battery life.

At Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) we have been working towards a solution. As a result, the development of the first hybrid battery suitable for storing electricity from renewable energy sources is now a step closer.

In partnership with Australian capital venture firm Cleantech Ventures, CSIRO has invested in technology start-up Smart Storage to develop and commercialize battery-based storage solutions.

The Smart Storage battery technology aims to deliver a low cost, high performance, high-powered, stationary energy storage solution suitable for grid-connected and remote applications.

Origin of the Smart Storage idea

The present fundamental problem with solar and wind generated power is its intermittency. The fluctuations make it more difficult to integrate the energy into the electricity grid than steady base-load power supplies. It is this inability of renewable sources to produce energy on demand that has slowed their uptake. And while there are products on the market – called remote area power supplies (RAPS) – that store energy produced during the day for use during the night, they are based on conventional lead acid batteries that have relatively short lives and require regular maintenance, which increases their whole-of-life cost.


The Smart Storage battery concept could make the intermittancy of wind power generation a thing of the past
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We knew that if we could store the energy that was being produced by renewable sources in an appropriate battery, that power could be released at a continuous steady rate and be much more easily integrated into energy supply systems.

The CSIRO Energy Transformed Flagship had already been trialling an energy storage system, dubbed the ‘UltraBattery’, with similar characteristics to those needed for renewable applications.

The battery technology

The products that Smart Storage is developing will be based on CSIRO’s ‘UltraBattery’, which has been successfully trialled in hybrid electric vehicles (HEV). In fact, just last month testing undertaken in the UK has further proved the UltraBattery’s capabilities with a HEV surpassing 160 000 km under strict and challenging conditions, using the power of the advanced battery system.


Figure 2: The UltraBattery has undergone rigorous testing in a hybrid electric vehicle in the UK during the last 12 months
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This hybrid battery combines an asymmetric ‘supercapacitor’ electrode and a lead-acid battery in a single unit cell. Advanced materials used for the electrodes and current management absorb and release charge rapidly, and at efficiencies well above conventional battery types.

A supercapacitor is a physical charge storage device that offers very high capacitance in a small package. They are able to store a large amount of charge (energy) that can be released very quickly – so they work as a kind of shock absorber at the front end of the lead acid battery. The supercapacitor copes with intermittent charge and discharge requirements and smooths out the charge and discharge of the battery’s lead acid component. This means they are superior in short duration, high-energy applications.

We have used the UltraBattery as the basis, and because of its robustness recognized the potential to use it for renewable energy storage. Also, the integration of batteries and supercapacitors allow manufacturers to develop smaller, lighter and cheaper battery units. This replaces the current, inefficient practice of fitting oversize batteries to cope with sudden surges in wind power.

Reliable and cheap power of the future

It is expected that the discharge and charge power of the Smart Storage battery will be 50 per cent higher, and its cycle-life at least three times longer, than that of the conventional lead-acid counterpart.

Importantly, as well as reducing ongoing costs, the environmental footprint of such a storage system is reduced because of the highly recyclable nature of lead. Around 97 per cent of all lead in lead-acid batteries is recycled which compares favourably to the disposal problems with other types of storage based on lithium or nickel-cadmium.

The high-power and long-life UltraBattery can be integrated into wind systems to smooth intermittency and potentially ‘time-shift’ energy production to better match demand. A similar application is expected to be developed for photovoltaic energy production.

From an industry point of view there are significant benefits. The power distribution industry is generally concerned with the supply of reliable, cheap power. They are responsible for managing the power grid and ensuring people get reliable, secure and cost-effective energy. The Smart Storage work is certainly of relevance to this industry because it offers a system that reduces cost and increases reliability and security.

Commercialization

The global market for portable rechargeable batteries is rapidly expanding, with a 17 per cent increase to $4.5 billion in 2003. Investments in energy storage technologies have excellent potential for strong returns given the growing market demand and the current lack of viable solutions.

Commercialization of the technology is expected to be approximately 12 months away, but once ready the products are likely to be marketed globally. Smart Storage’s technology development path is directed towards manufacturing in existing lead-acid battery plants.

Costs are still to be determined, but Cleantech Ventures expect the long life and low cost of the batteries will make them very commercially attractive.

Looking to the future

At this stage, the battery’s main applications will be for wind and solar energy, but there are also possible applications for wave power, given its intermittent and fluctuating nature.

The next steps are to find ways to reduce costs and have many more deployments of the system. We also need to do extensive work to define where such technology should be located.

At the same time, our researchers need to identify ways to increase storage capacity, as the current battery is only suitable for small -scale applications (i.e. less than one MW), so we need to be find ways to store into the tens of megawatts.

Our vision is 24-hour, seven-day a week continuous power from renewables and this battery is a step in the right direction.