Comparison of battery chemistries for energy storage solutions

Advanced battery energy storage solutions can improve renewable energy efficiency, and the need is growing exponentially. In 2021, approximately 20 percent of electricity production came from renewable energy sources. According to the International Energy Agency, this number must increase to two-thirds by 2030 to achieve net zero goals. To truly unlock the potential of renewables, we need larger energy storage systems, and it will take a wide variety of battery chemistries to meet that demand.

The three widely used battery technologies are lead, lithium, and vanadium redox flow. There are a number of factors to consider when selecting the most appropriate battery chemistry to meet your energy storage needs.

Commercial maturity

Like other technologies, batteries have evolved in design and manufacturing. Due to ambitious clean energy transition goals, the public and private sectors must make combined efforts to accelerate innovation, from research and development to the prototype and early adoption phases.

Invented in 1859, lead is the most mature of the three battery technologies and has been the primary energy storage solution for many years. Regardless of its longevity, there are still areas where further research could uncover even more potential capacity. Lead is also relatively inexpensive compared to other battery chemicals.

Lithium is another commercially mature technology on the scale needed today. It was originally used for consumer products in the early 1990s. With its high energy density, lithium is currently the dominant battery technology for energy storage. Lithium is available in a wide variety of chemical combinations, which can be somewhat daunting, with nickel manganese cobalt (NMC) and lithium iron phosphate (LFP) having the highest levels of maturity.

Although vanadium redox flow battery technology has been around for over 50 years, it is the least commercially mature of the three chemistries. The concept of vanadium flow batteries was developed by NASA to power satellites. This chemistry has the potential to become a cutting-edge solution for long-term energy storage.

Sustainability

Renewable energy must be efficiently acquired and distributed to be sustainable. The energy storage solutions used to achieve this goal must also have a low environmental impact.

Lead is the most durable of the three battery chemistries. Lead acid batteries have a 99% recycling rateand the lead acid battery industry is well developed circular economy which reuses and recycles lead, electrolyte and plastic components from used batteries.

Vanadium is almost infinitely reusable. The electrolyte that makes up most of a vanadium battery system can be dried, purified if necessary, and then used in another system. According to the US Geological Survey, about 40 percent of vanadium is recycled.

Currently, lithium is the least durable of the three chemistries. The recycling rate is less than five percent, due to the cost and complexity of the process. A lithium battery must be disassembled and crushed, then melted or dissolved in acid. Although recycling processes are not yet widely available, this rapidly evolving field will improve material capture from lithium batteries. These new solutions are already producing modest amounts of battery-grade materials at a fraction of the cost of virgin materials.

Operating time

Common applications for energy storage include energy transfer, such as storing renewable energy for use at another time or storing grid energy for use during an outage. Each of these applications has a different run time, and this duration is a factor when choosing the most appropriate battery chemistry.

Vanadium is best suited for long-term energy storage (six hours or more of run time). It has a larger footprint, but is easier to expand. In order to increase the duration, more electrolyte is added to the battery system. Size and weight must be taken into account for vanadium systems, but these systems can be approximated thanks to the high level of security offered by these systems.

Lithium is suitable for short to medium durations (from a few minutes to four hours of operation). In order to increase duration, additional cells are added to the battery system, increasing the footprint and planning needed to meet emergency access requirements in the event of a security event. There is a tipping point, as cells are needed to increase duration, where the footprint of a lithium system, with proper safety spacing, can exceed that of a vanadium system.

Lead also works best for short to medium duration, especially in situations where depth of discharge is quite low and low initial cost is a major trigger. It is possible to increase the duration by adding cells, similar to a lithium system. However, weight and space are important factors in increasing uptime.

Useful life

Useful life is a combination of life cycle, calendar life and operating environment. The useful life of a lithium battery is around 10 to 15 years, while vanadium can last over 30 years. Lead-acid batteries can have a useful life of up to 30 years, depending on design and applications.

Lead acid batteries are usually measured by life which is strongly influenced by depth of discharge conditions, with a capacity of 1200-1800 cycles at 80% depth of discharge depending on design. Lithium battery life is typically specified at much greater depths of discharge in the 80-100% range and provides two to three times the life of a lead-acid battery with approximately 3,000-10,000 rounds. In contrast, vanadium battery technology has an almost infinite lifespan. For all battery technologies, these lifetimes depend on proper maintenance.

Lead and lithium are sensitive to high temperatures. The ideal operating temperature for these battery systems is between 20°C and 35°C, with some impact on life beyond this range. Vanadium systems can tolerate higher heat, up to 50°C.

Photo credit: Stryten Energy

Security

All three battery systems are generally safe, assuming no faults or damage. Lithium batteries are sensitive to high temperatures and inherently flammable. If the temperature rises above a critical level or damage results in an internal short circuit, thermal runaway occurs. A battery management system ensures the lithium cells remain within their specified operating range. As an added precaution, lithium batteries should be separated as much as possible to prevent a fire from spreading throughout the system.

Safety issues with lead-acid battery systems are often determined by their design. Flooded systems contain liquid electrolyte, requiring containment in the event of a rupture and ventilation in the event of potential gassing. VRLA batteries require a well-designed charging system to monitor and manage voltage and temperature. Lead is also susceptible to thermal events, but these events are much more easily contained compared to lithium battery systems.

Compared to other battery technologies, vanadium is generally considered safer. Although the electrolyte itself is not flammable or subject to thermal runaway or deflagration events, it is corrosive and requires adequate containment strategies.

Supply Chain

Energy is vital to keep our economy moving. By diversifying our energy sources, our country is better protected from supply shocks influenced by foreign imports. Import dependence also leads to security vulnerabilities. Recent supply chain shortages and disruptions have proven that a national supply chain should be another important consideration for energy storage systems.

Lead is readily available and produced locally. Domestic recycling provides 73 percent domestic demand for lead. More 90 percent of domestic lead-acid battery demand is met by North American manufacturers. The U.S. lead-acid battery industry supports more than 92,000 jobs and more than $26 billion in overall economic benefits.

Lithium is one of 50 mineral raw materials listed as critical to the US economy and national security. Australia is the world leader in lithium mine production, followed by China and Chile. While the United States has about 4% of lithium reserves, we produce less than 2% of the global supply.

Vanadium is also on the list of critical minerals. China is the world leader in vanadium production, then South Africa and Russia. Currently, there is no domestic production of vanadium, leaving the United States dependent on foreign sources.

Conclusion

The energy sector is the source of 76 percent greenhouse gas emissions worldwide. Replacing fossil fuel with energy from renewable sources would significantly reduce carbon emissions. The United States has set an objective achieve net zero emissions by 2050 and create a carbon-free electricity sector by 2035.

To achieve this goal, emphasis will be placed on renewable energy sources such as wind and solar. This transition to clean energy will require multiple, reliable, sustainable and safe energy storage solutions. These solutions will depend on a variety of advanced battery technologies, and each chemistry will have its place to match supply with demand.

This article is supported by Stryten Energy.


 

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