What is "intermittency" really?
Written By: Lauren Rosenthal, Edited by: Vanessa Lu Langley
The role of renewables in our energy systems is growing at a rapid pace. Increasing global awareness about the need to transition away from fossil fuels paired with increasingly cost-competitive technology have provided tremendous momentum to plans to shift towards sources like solar and wind energy (Gowrisankaran et al., 2016). However, these sources still have a major shortcoming that remains unresolved: intermittency. Intermittency refers to power that is not consistently and continuously available. This is the case for sources such as solar and wind, as they are non-dispatchable, meaning that they, and consequently, their energy output, cannot be controlled on command. This leads to a potential mismatch between the amount of energy available and society’s grid demand at any given moment.
For instance, in the case of solar energy, the sun does not shine all day at one location, and its rays can easily be dampened by cloud cover (Hanania et al., 2020). Typically, the sun tends to shine brightest in the middle of the day, while people tend to consume the most energy in the evening after arriving home from work. This means that in the middle of the day, there will be an excess of solar energy available compared to the demand, while at the end of the day, once the sun has set, there will be insufficient energy to meet the demand (Susser, 2018). Similarly, for wind energy, the presence of wind and its intensity at a given location are highly variable (Hanania et al., 2020), meaning that a peak in wind energy generation may not coincide with a peak in energy demand.
The most commonly proposed solution to this problem is energy storage: surplus energy produced compared to the demand can be kept for a future time when energy output is lacking. As of now, existing technologies are unable to tackle this problem at the spatial and time scales required while also being economically viable (Spector, 2020). For instance, while large lithium batteries have been proposed as a storage solution, they can only store energy for weeks at most, making them unable to preserve energy from one season to the next (Rathi, 2017). Finding truly viable energy storage options for intermittent, renewable energy sources is a rapidly developing area of research. Although there are some potentially promising ideas floating around, such as the use of compressed air to store energy to be re-released later, the problem of intermittency is far from resolved (Spector, 2020). However, the 2020s have been dubbed the “energy storage decade” (Balaraman, 2021), as this sector is rapidly growing as people recognize not only the economic potential of renewable storage, but the need to make renewables work over the long-term. The future of the transition towards sustainable energy depends on it.
Balaraman, K. (2021, November 17). “The energy storage decade”: Global market poised to reach 1 TWh by 2030, BNEF finds. Utility Dive. Retrieved November 19, 2021, from https://www.utilitydive.com/news/the-energy-storage-decade-global-market-poised-to-reach-1-twh-by-2030-b/610211/
Gowrisankaran, G., Reynolds, S. S., & Samano, M. (2016). Intermittency and the Value of Renewable Energy. Journal of Political Economy, 124(4), 1187–1234. https://doi.org/10.1086/686733
Hanania, J., Stenhouse, K., & Donev, J. (202–04-28). Intermittent electricity. Energy Education. Retrieved November 19, 2021, from https://energyeducation.ca/encyclopedia/Intermittent_electricity
Rathi, A. (2017, December 14). Batteries can’t solve the world’s energy storage problem. Electrochaea thinks archaea could. Quartz. Retrieved November 19, 2021, from https://qz.com/1133123/batteries-cant-solve-the-worlds-biggest-energy-storage-problem-one-startup-has-a-solution/
Spector, J. (2020, April 1). The 5 Most Promising Long-Duration Storage Technologies Left Standing. Green Tech Media. https://www.greentechmedia.com/articles/read/most-promising-long-duration-storage-technologies-left-standing
Susser, J. (2018, March 13). Why is Peak Demand a Concern for Utilities? Advanced Energy. Retrieved November 19, 2021, from https://www.advancedenergy.org/2018/03/13/why-is-peak-demand-a-concern-for-utilities/