Most everyone who is invested in solving climate change is aware that one of the most important steps we must take is to move away from oil and gas as our main energy forms and towards renewable energy such as solar and wind. However, renewable energy faces intermittency issues that make it difficult to fully transition to renewables as our primary energy source. For example, demand for power heavily misaligns with when the sun is out, in a phenomenon known as the “duck curve.” This makes it nearly impossible to compose a stable grid solely of renewable energy without large quantities of energy storage. Currently, there is no low-cost, large-scale energy storage that is able to support a full transition to renewable energy.
The Duck Curve: This graph shows energy usage throughout a day. Energy demand is lowest in the middle of the day when solar energy generation is the highest leading to overgeneration. Energy demand peaks in the evening when it is dark meaning that the demand is too high for solar energy to account for (The Duck Curve | NuScale Power)
There are a few battery technologies currently being considered in development for large-scale energy storage. These include lithium ion-batteries, sodium-sulfur batteries, and redox-flow batteries. My research is in redox-flow batteries, an incredibly exciting technology with high industrial potential.
In general, batteries work by moving electrons from one material to another via an external circuit. The materials that the electrons are moving between are called electrodes. Each battery has two electrodes referred to as a cathode and an anode. The movement of electrons creates current. Redox-flow batteries work by converting chemical energy, the energy stored in the bonds of the chemical compounds, into electrical energy, the movement of electrons, using reduction and oxidation reactions of liquid electrolytes.
If you haven’t taken general chemistry (or if you have and forgot it all!) redox stands for reduction and oxidation, which refers to an atom gaining or losing an electron. The liquid electrolytes consist of a metal such as vanadium or chromium along with molecules called “chelates” attached which are then placed in water. The chelates are usually large organic molecules that can attach to the metal in multiple places. These chelates are often common, cheap, and nontoxic chemicals such as EDTA which is found in many fertilizers, foods, and medicines. Chelates can improve the stability of the molecules and speed of the reactions which allows the metal-chelate complexes to have the reduction and oxidation reactions necessary to move electrons through the circuit.
Diagram of a redox flow battery. Tanks hold the liquid electrolytes which are denoted here as the anode and the cathode (“Solid Dispersion Redox Flow Battery”)
Redox flow batteries have high potential in large scale energy storage because they are easy to scale up; by simply increasing the volume of the liquid electrolyte, you can increase the battery capacity. Already, these batteries are beginning to be deployed for energy storage. In South Africa, an entire electrolyte manufacturing plant is being built to produce Vanadium flow batteries on a large scale (Vanadium Producer Bushveld Minerals Begins Building Flow Battery Electrolyte Plant in South Africa | Energy Storage News). In the United States there is a severe lack of energy storage but of the energy storage available 90% is lithium-ion batteries (Battery Storage in the United States: An Update on Market Trends). Lithium-ion batteries have many shortcomings including toxicity and safety concerns. The toxic and expensive materials needed to make the lithium-ion batteries contribute to issues with using them on a larger scale. Ideally, they could be replaced by safer and less toxic redox-flow batteries.
This science is extremely promising but is it enough to help us transition our energy system? To answer this, we must consider not just the science, but also how redox-flow batteries will be incorporated into our electrical grid. In integrating this technology, we must be mindful of the larger societal shifts that can lead not only to a more sustainable world, but also a more just one. The ongoing transition to renewable energy provides an exciting time to correct many global inequalities.
The Organization for Economic Cooperation and Development (OECD) has put together a report on a just transition to incorporate sustainability and equality into the fight to solve climate change. Some of the guidelines in that report include establishing new infrastructure that considers marginalized communities and strives to be inclusive. For example, workers in the oil industry must be retrained in renewable energy jobs so that entire communities don’t experience crippling job losses. Additionally, current materials for batteries are often sourced from unethical mines in developing countries. Taking these unjust impacts on communities and land while sourcing materials for batteries into consideration is something that must happen for a renewable energy transition to truly benefit everyone.
All told, without better energy storage it will be very difficult, if not impossible, to solve the climate crisis. The electrification of our energy sources is a key part of many climate plans, and this will take massive amounts of energy storage. If battery storage is not thought about in the context of environmental justice, many communities will likely be harmed in the process of transitioning to these systems. However, if implemented properly, battery storage is a crucial tool in transitioning to a more equitable, and sustainable, world.
Vanadium Producer Bushveld Minerals Begins Building Flow Battery Electrolyte Plant in South Africa | Energy Storage News. https://www.energy-storage.news/news/vanadium-producer-bushveld-minerals-begins-building-flow-battery-electrolyt. Accessed 14 July 2021.