The question of energy storage is very much in the news now due to the already developed systems or those that are promising, but under development. The concept became more important since the wide spread of renewable energy.
But energy storage is not new. When a car battery is charged, a clock spring is wound, a car tank is filled with gasoline, natural gas compressed and filled in pipelines or caverns are all forms of energy storage. On a larger scale, the most mature and widely used is pumped storage where surplus electricity from hydroelectric dams is used to pump water to an elevated reservoir only to be drained later in the day to generate further electricity when the load increases.
However, this column is concerned about the more substantial use of modern devices to store electricity or heat.
The variability of solar and wind energy necessitated the need to create a buffer between the generated electricity from these sources and the grid they are connected to. Lithium ion batteries are the most widely used for the purpose now. This trend is benefiting from advances in battery technology and reduction of cost as the use increased.
Therefore, electricity is generated when the sun is rising or the wind is blowing and the surplus is stored for later needs.
Even on a household scale, the technology is finding a market among those having solar panels or wind turbines. In Australia for example, the “Guardian” reported that “more than 1.1 million new battery storage systems will be installed in Australian households by 2035. And battery storage capacity is expected to grow 50-fold in under a decade.”
At the grid level, the load changes all the time as users switch applications on and off and storage can smooth the operation and prevent frequency variations or upsets. The problem is that lithium is still expensive and its supply is limited and therefore the search for other battery technologies goes on.
Research and development is well under way to replace lithium with the more available and much cheaper aluminium and to develop other batteries such as sodium-sulphur and zinc-bromide or even the traditional lead-acid.
Nevertheless, the world’s largest lithium ion storage system of 30MW was commissioned last February in California to augment a natural gas electricity generation plant. The same company is targeting 165- and 330MW storage by 2020 and 2030 respectively. The UK announced a tender for 201MW battery storage system costing $86.4 million.
The other form of energy storage is in thermal systems where renewable electricity or electricity purchased from the grid at off-peak rates is used to heat and melt salt or silicon to a high temperature of 1,414 degrees and later recover the heat for power generation or district heating or cooling.
The same system can be used directly by the heat generated from concentrated solar collectors. The system is said to be cheaper than battery related applications, especially as its working medium is inexpensive and battery life is limited.
McKinsy & Co takes a dimmer view as they said that “storage will not be economical any time soon” and that “storage constitutes a very small drop in a very large ocean.” Yet in 2015, a record 221MW was installed in the US and that capacity would grow to more than 1GW by 2019 compared to a generation capacity of 1000GW.
The same consultant says that the US energy storage market could be worth $2.5 billion in 2020 and global potential for storage could reach 1,000GW in 20 years.
In the future, it is expected that energy storage will be integrated with large-scale power stations to satisfy surges in demand and thereby reducing the need and substituting for standby generating units.
Storage manufacturers in the US installed 70MW in just six months compared to years needed to install gas turbines. The fact that batteries are made in modules of one MW increments makes installation highly scalable.
Naturally, the storage systems are likely to contribute to the reduction of carbon emissions from power generation facilities by storing energy from intermittent renewables or by reducing the number of on and off traditional generating units depending on fossil fuels.
This will encourage energy storage applications in countries who have made commitments to reduce carbon emissions.
In our region, there is a need to research what the most appropriate storage system should be pursued, especially that summer heat is likely to affect battery based systems. With increasing plans to use renewable energies in many countries, energy storage is a necessary complement.
To start with, energy storage should be incorporated with new power projects and contractors asked to submit options that may give decision-makers good ground to make appropriate selection.