Our recent blog posts have focused on CCS as a solution for the reduction of greenhouse gases. We are now turning our attention to another issue associated with the move to a more diverse energy mix, the issue of energy storage.
Over 80% of global primary energy is supplied by fossil fuels, with demand set to increase by over 2% per year from 2015 to 2040 (Abdin et al., 2019). Diversification of the global energy mix by the introduction of green energy sources (e.g. wind and solar) is required to help reduce our reliance on oil and gas. The major drawbacks of renewable energies have been the exorbitant cost of the new technologies, and their intermittent nature; the sun only shines in the day, and wind energy is only produced when it is windy.
Source: DECC via BBC News
Figure 1 above shows how the increase in renewables as a share of the UK electricity mix may create issues of scale, as overall global energy demand continues to rise in tandem. Compounding this issue is the fact that energy production from renewable sources such as diurnal photovoltaic cells, does not line up with the peak demand times for energy – put simply, we cannot make energy from the sun after it sets. Herein lies the challenge: increased levels of energy sourced from renewables requires a significant increase in energy storage capacity.
Energy storage concepts have existed in one form or another for thousands of years. What was potentially the first primitive battery was discovered in Baghdad (Figure 2), and dates back to the days of the Parthian Empire (247 BC – 228 AD). This contraption used a rod of iron and tube of copper attached to a clay pot, to conduct electrons and generate a low-voltage current from fermented juice within. Its original purpose is unknown, but it serves as an example of ancient thinking on battery usage and energy storage (Dănilă, 2010).
Source: Dănilă, 2010.
The development of more modern batteries in the 19th & 20th Centuries heralded an age of increased energy storage capacity, in line with the ever-increasing demand for energy consumption. Rechargeable lead acid batteries were first developed in 1859 as the first rechargeable method of electrical energy storage (Chen et al., 2009).
Energy storage exists primarily to bridge the gap between production and consumption, enabling a consistent output, which is often cheaper and more efficient. The primary concept behind this is that of peak load ‘shifting’ or ‘shaving’; when the generation of energy by a system is shifted to align with peak demand, even when the source itself (such as a photo voltaic cell), is not generating enough energy to cover said peak demand. Energy Storage Systems can also increase the ‘power quality’ of energy facilities; by maintaining a consistent voltage and frequency, the output can offset any fluctuation in power reliability. Figure 3 below shows energy demand in blue, with energy generation following peak shifting in red. When the red line exceeds the blue line, energy is stored, and used to feed those times of increased demand (when the blue line exceeds the red).
The implementation of Energy Storage Systems solutions can reduce operating costs of facilities when it is working at a sufficient efficiency. With the need for mitigation of variable load and renewable energy supplies, power quality and storage options play a critical role, and Energy Storage Systems presents potentially the most important option for managing our energy through the low-carbon transition (Abdin et al., 2019).
A supply of electrical energy must always have its generation and consumption demand matched in order to prevent blackouts or costly energy wastage. An electrical power grid contains no inherent storage capacity, so a mix of solutions and sources known as an Energy Mix, must be employed to meet fluctuating demand across nations and globally. This is in contrast to the physical nature of a gas grid, whereby gas supply can be readily increased, decreased, and stored within the grid itself (Crotogino et al., 2017).
Conclusion
As we need to increase the amount of renewable energy in the energy mix going forward, the requirement for energy storage solutions is imperative. These solutions help to bridge the gap between intermittent renewable energy production and consumer demand. If used properly, energy storage systems can also reduce the cost of facilities, by maintaining a consistent voltage and frequency.
Future blogs will discuss the viability of specific energy storage techniques, such as Compressed Air Energy Storage.
David Whitworth, Junior Geologist
References:
Abdin, Z., Khalilpour, K.R., 2019. Single and Polystorage Technologies for Renewable-Based Hybrid Energy Systems, in: Polygeneration with Polystorage for Chemical and Energy Hubs. Elsevier, pp. 77–131. https://doi.org/10.1016/B978-0-12-813306-4.00004-5
BBC, DECC, 2013. UK energy mix: Where does our power come from? URL https://www.bbc.co.uk/news/business-24823641
Chen, H., Cong, T.N., Yang, W., Tan, C., Li, Y., Ding, Y., 2009. Progress in electrical energy storage system: A critical review. Progress in Natural Science 19, 291–312. https://doi.org/10.1016/j.pnsc.2008.07.014
Crotogino, F., Schneider, G.-S., Evans, D.J., 2018. Renewable energy storage in geological formations. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, 100–114. https://doi.org/10.1177/0957650917731181
Danila, E., 2010. History of the fist energy storage systems. Presented at the IEEI 2010 3 RD INTERNATIONAL SYMPOSIUM ON THE HISTORY OF ELECTRICAL ENGINEERING AND OF TERTIARY-LEVEL ENGINEERING EDUCATION, Unpublished. https://doi.org/10.13140/2.1.1564.7040
