Aaron Valentine
Sustainability Problems
Why Worry
9/16/12
The need for grid scale energy storage
Energy is an important resource in modern culture and society. Unfortunately the majority of
the resources used to generate it are in declining supply, therefore it is important to be as efficient as
possible when generating and supplying it. Grid scale energy storage helps in attaining both of these
goals, both by allowing current plants to operate at a higher efficiency, and to allow for easier
integration of renewables into the grid.
In order to understand the importance of grid scale storage, one must first understand how
power is generated and distributed. There are two basic types of plants, Base load plants such as coal
and nuclear, and peaker plants run on natural gas. Base load plants typically have a slow ramp rate and
long response times when compared to peaker plants, but provide cheaper electricity then peaker
counterparts when running at full capacity. As such base load plants provide the base load power as the
name implies, and peaker plants are used in response to fast changes in demand(1). Grid scale storage
takes the cheap excess energy generated by base load plants during off peak hours and stores it until
needed during peak hours. This allows the base load plants to operate at highest efficiency, while
reducing the demand for more expensive fuel used by peaker plants. Grid scale storage also allows for a
better transition into renewable energy as storage required for intermittent energy sources such as
wind and solar are already built into the system.
There are varying types of grid scale storage systems, the most common being pumped water
storage, but battery based systems and thermal systems also exist. Pumped water storage works much
like a hydroelectric dam, only during off peak hours water is pumped back into the reservoir thus storing
the energy. The US currently has about 16.5 GW of pumped storage capacity (2). Pumped storage has
the same strengths and drawbacks as hydroelectric, providing low response time, but requiring large
amounts of space and capital to construct. Battery storage is showing more promise, with new
technologies using cheap resources such as a liquid battery using magnesium and antimony (3) instead
of expensive rare earth elements such as lithium.
The benefits of including grid storage into the current system cannot be over stated, a report
released by Sandia National Labs in 2010 listed 26 benefits to building grid storage ranging from a more
robust grid, to better air quality to easier integration of renewable energy into the system(4). By storing
excess energy locally, it is possible to avoid inefficiencies caused by transmission losses, and reduces the
chances of cascade failures such as the 2003 power outage by reducing the reliance on a handful of
transmission lines to provide power.
So why worry? Well for one, there isn’t a lot of talk about grid scale storage happening right
now, most of the focus is on clean coal or natural gas, as such it is hard to find data on how much
investment is actually being done, only bits and pieces. However, it is known the benefits that increasing
the capacity of grid storage systems can bring, which is why further investments are necessary to
mature this technology and create a more efficient grid.
Bibliography
1)Eskom. Base and Peak Load Electricity. N.p.: Eskom, n.d. Generation Communication, June 2010. Web.
Sept. 2012. <http://recruitment.eskom.co.za/content/GX_0003BasePeakElecRev5.pdf>.
2)"Pumped Storage Projects." FREC. Federal Energy Regulatory Commission, 29 Aug. 2012. Web. 17
Sept. 2012. <http://www.ferc.gov/industries/hydropower/gen-info/licensing/pump-storage.asp>.
3)Bradwell, David J., Hojong Kim, Aislinn Sirk, and Donald Sadoway. "Magnesium−Antimony Liquid Metal
Battery for Stationary Energy Storage." Journal of the American Chemical Society 2012.134 (2012): 18951897.
4)Eyer, Jim, and Garth Corey. Energy Storage for the Electricity Grid: Benefits and Market Potential
Assessment Guide. Rep. no. SAND2010-0815. Albuquerque NM: Sandia National Labs, 2010.