Rethinking energy storage: Looking beyond batteries
June 17, 2024
Energy storage solutions are helping us reimagine how we create and store the energy we use every day. Here¡¯s how.
Given the highly intermittent nature of key renewable energy resources such as solar and wind, energy storage has become critical to the functionality of our power grid. At a high level, energy storage systems do precisely what their name suggests¡ªthey gather energy and store it for later use.
There is a wide variety of energy storage systems, each based on different technologies and forms of energy. While some of these technologies are well-established, there remains significant room for research and development. This has led subject matter experts across the energy industry to ask imaginative questions, such as: How can abandoned mine sites be converted into pumped storage energy facilities? And how can we leverage advances in thermal energy storage (TES) technologies to store energy more efficiently?
Let¡¯s delve into some emerging energy storage solutions that can help us reimagine how we create and store the energy we use every day.
Energy storage systems each have a unique set of characteristics that impact how they might be used to support a 100% renewable energy system.
Expanding pumped energy storage
Pumped storage, a modified use of hydropower technology, serves as a clean energy storage method suited for electricity grids. This is especially true for those that are increasingly dependent on intermittent energy sources like solar and wind. These projects manage energy by transferring water between two reservoirs at different elevations, capturing surplus energy during low-demand periods and releasing it during peak demand.
The deployment of pumped storage is geographically constrained due to the need for two reservoirs with a significant elevation difference. To expand deployment opportunities, experts are investigating the feasibility of converting retired mine sites into pumped storage reservoirs.
Mines with suitable characteristics could provide the ideal infrastructure for developing pumped storage projects after closure, potentially storing a considerable amount of renewable energy. For instance, a deep mine with a large pit or an extensive tunnel network could serve as a vast lower reservoir, utilizing the natural elevation gradient to facilitate the uphill pumping of water for temporary storage. Our teams in Queensland, Australia, are currently assessing the potential for establishing a pumped storage project at the Mt Rawdon mine.
Similar to conventional hydropower, pumped storage converts the energy of flowing water into electricity. The outcome is a 'rechargeable battery' that harnesses well-established technology for energy storage. Moreover, pumped storage projects are economically feasible, often utilizing low-cost excess grid power for pumping and generating electricity when the market price of power justifies the pumping cost.
Mount Rawdon Mine in Queensland, Australia could be a potential pumped storage site.
Thermal energy storage breakthroughs
Thermal energy storage (TES) technologies are pivotal in boosting energy efficiency and managing supply. They play an essential role in our shift towards a sustainable power grid. They offer huge potential in a variety of applications, from industrial processes and electricity generation, to the heating and cooling of buildings and homes. This makes them a potential cornerstone for clean energy economies and lifestyles. As we transition away from fossil fuels and increasingly depend on variable renewable energy sources, TES technologies offer a suite of solutions adaptable to various temperature ranges and storage durations.
Most solar energy generation comes from photovoltaic panels, which generate electricity only when the sun is shining. This results in no power production at night and reduced output on cloudy days. An alternative is concentrated solar power (CSP), which captures solar heat. CSP can be combined with molten salt thermal storage, enabling the system to produce electricity even after the sun sets. This method converts the sun¡¯s variable energy into a dispatchable energy source, ensuring a more consistent electricity supply to the grid.
Innovative technologies such as ¡®sand batteries,¡¯ currently under development in countries like Finland, also show promise. Heated sand retains thermal energy effectively due to its high specific heat capacity. When there¡¯s a demand for heat, the stored thermal energy is retrieved from the sand. A heat transfer fluid¡ªsuch as air or water¡ªis circulated through the sand bed, absorbing the heat and transporting it to where it¡¯s needed. For instance, in residential heating systems or industries that rely on fossil fuels.
A concentrated solar power site.
Unleashing the power
Energy storage systems each have a unique set of characteristics that impact how they might be used to support a 100% renewable energy system. These can include the scale of the system as well as the power capacity, duration, and efficiency of the energy storage system itself.
Just as pumped storage requires specific geographic conditions that may limit their deployment, the efficiency of different thermal energy storage systems will vary. For example, some loss of energy has been known to occur during the process of storing and retrieving energy, reducing the system¡¯s overall efficiency. Luckily, there is an entire body of research that explores how to develop energy storage for longer periods of time across days, weeks, or even seasons.
The uncertainties surrounding the deployment and economic viability of emerging energy storage systems are to be expected. They underscore the importance of continued exploration in this field. Energy storage systems have the potential to be transformative, serving as a reminder to those of us in the industry that we play an active role in reshaping the energy landscape.
By embracing these emerging technologies, we are on the path to a future where every watt of energy can be utilized to its full potential.
Harnessing the future
Delving into the energy storage systems discussed earlier provides potential solutions to the intermittent nature of renewable resources such as solar and wind. And it will be instrumental in transitioning to a more sustainable power grid. The potential of pumped storage, coupled with the advancements in TES, opens up a world of promising possibilities.
By embracing these emerging technologies, we are on the path to a future where every watt of energy can be utilized to its full potential.