Grid-Connected Energy Storage: the Key to Sustainable Energy?
Professor Tony Vassallo, Delta
Electricity Chair in Sustainable Energy Development, School of Chemical
& Biomolecular Engineering, University of Sydney, NSW 2006
Date: Wednesday, 2nd November, 2011 at 6:30 pm
Venue: New Law Lecture Theatre 106, New Law Building, University of Sydney
Grid-connected Energy Storage: the Key to Sustainable Energy?
Many countries in the world are committing large amounts of research resources to the development of sustainable energy generation technologies. One major disadvantage in using electricity as an energy source is that it is difficult to store. Renewable energy sources have the added problem that they are only available at certain times. For example, solar energy is only generated when there is strong sunlight.
At the meeting of the Society in Sydney on 2 November, Professor Tony Vassallo, the Delta Energy Professor of Sustainable Energy Development at the University of Sydney, gave a comprehensive coverage of the issues, challenges and potential advantages of having energy storage that can be directly connected to the electricity distribution grid.
There are important technical and economic reasons for wanting to store energy so it is quickly accessible to the consumer via the grid. Electricity demand varies quite substantially over the day, with this pattern also depending on the time of year. In summer, air-conditioning loads in the afternoon are high, while in winter loads peak in early evening and early morning. Most of Australia's electricity is generated in large, coal-fired power stations and these can take hours to react to changes in demand, so for these to be able to respond without the risk of blackouts, a lot of energy is wasted. Currently, the only means of providing reasonably responsive energy to the grid is via the Snowy Mountains hydroelectric system.
Many technologies are currently being developed to provide energy storage capacity. These include thermal storage using molten salt (for example, in Spain), hydroelectric storage, compressed air, superconducting magnets, ultra-capacitors, high-energy/high-efficiency flywheels and a range of battery technologies.
One promising technology avenue is integrating battery technology with renewables. For example, used in conjunction with wind energy generation, battery storage can reduce short-term fluctuations and allows dispatch when the load is high. It also allows a higher proportion of the total wind generation capacity to be included in the calculation of base-load capacity and lowers the capital cost of transmission equipment because the variability in load is reduced. The question Professor Vassallo addressed was: is battery technology feasible?
Currently large battery banks have been installed in pilot installations in other parts of the world, for example a 34 MW battery bank in a 50 MW wind-farm in Japan. But it may not be necessary to install such large battery banks that have high capital cost. For example, batteries can be distributed throughout the grid to zone substations and local substations. Another innovative concept is to use the batteries in electric cars to provide storage – during the times when demand is high and cars are not being used (for example early afternoon on a hot day), car batteries connected to the grid could provide localised storage capacity. Commercial models of these concepts are currently under development.
Professor Vassallo's own research programme relates to developing advanced battery and super capacitor technologies, such as graphene/nanotube capacitors, the use of regenerative fuel cells and the role of distributed storage in electricity networks.