The storage of renewable energy is a significant challenge for wind and solar energy to become the primary source of electricity. While they currently offer unprecedented efficiency – with photovoltaics exceeding 20% – the stability of production is still affected during night-time or windless periods. Luckily, researchers at MIT have developed a unique semi-solid battery that could provide a solution to this challenge.
In addition to discussing the innovative MIT battery in this article, we will also explore other renewable energy storage solutions, such as the following:
The “molasses” battery
The MIT device is technically a semi-solid flow battery, resembling molasses in consistency and color. Recent research published in the scientific journal Joule demonstrates that this solution could be cheaper, more efficient, and scalable than current options. These new batteries are designed to store electricity from variable renewable energies using zinc-manganese oxide as the main ingredient.
One of the challenges in flow batteries, such as vanadium batteries, is the high cost of chemicals used for storing electricity on a megawatt scale. To address this, researchers combined manganese with carbon black to create a unique solution that reacts with a conductive zinc solution. The viscosity of these electrolytes allows them to flow while preventing the electroconductive particles from settling at the bottom when not in use. This balance between cost, performance, and durability was achieved during the prototyping phase.
The zinc-manganese battery is an advancement in flow batteries, offering high charging and storage capacity in a short period. Below, we will discuss other renewable energy storage techniques.
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Redox flow batteries
Flow batteries were first investigated in the 19th century and have evolved over time. NASA developed the first redox flow battery in 1973 for a potential electrically powered lunar base project. In the 1990s, vanadium redox flow batteries gained industrial use, primarily based on iron and chromium. These batteries can have high production costs, but advancements in using organic materials are making them more sustainable.
Redox flow batteries operate based on liquid electrolytes and a process of reduction and oxidation. Different oxidation and reduction states are applied to allow ion exchange through membranes. Vanadium, and now bromide, are commonly used in redox flow batteries, with the goal of creating environmentally friendly systems for storing renewable energy.
In addition to vanadium, other redox batteries have been developed based on organic materials, closing the ecological circle in renewable energy storage.
Green hydrogen
Another method of storing renewable energy is through green hydrogen production. Electrolysis processes can generate hydrogen using renewable energy sources, such as water. Countries like Spain and the USA are investing in green hydrogen as a stable renewable energy solution. By 2040, the cost of green hydrogen is expected to rival that of hydrogen produced from fossil fuels.
Pumped-storage hydroelectricity
Pumped-storage hydroelectricity involves using renewable energy to pump water to higher reservoirs during surplus electricity periods. This water is then passed through turbines during times of need. Various reservoir types, including natural, artificial, seawater, and underwater, can be utilized for this storage method.
Compressed air
Ontario, Canada, houses a compressed air renewable energy storage plant capable of producing 1.75 MW/hour for six hours, with plans for expansion. This technology utilizes compressed air stored in cavities to drive electric turbines, offering a cost-effective and environmentally friendly storage solution.
Molten salts
Molten salt systems store energy using heat generated from a solar thermal power plant. Various salts, such as sodium, potassium, and calcium, are heated using a solar concentrator and stored in tanks for later use. The heat retained in molten salts can provide energy for an entire week, making it a promising technology for renewable energy storage.
If you want to learn more about alternative renewable energy sources and storage solutions, we recommend reading this article. It provides insights into innovative approaches to harnessing the potential of renewable energies.
Sources: MIT
