Energy Storage Systems — Way towards Renewables
Energy Storage Systems are the set of methods and technologies used to store energy. The stored energy can be drawn upon at a later time to perform useful operations or to produce electricity. In this blog, we’ll be discussing three kinds of ESS. Particularly we’ll focus on the design concepts of companies/ startups that are working in this domain to bring up a breakthrough in the power sector.
- Thermal Energy Storage Systems
- Compressed Air Storage Systems
- Flywheel Energy Storage Systems
Ever heard that renewables are the future of energy? Today, we’ll discuss some of the developments in the energy storage sector that can make this shift towards renewables possible… Wait, What?… How can development in storage systems make the shift towards renewables possible? If you are wondering about this, then let me tell you that renewable resources specifically wind and solar are not consistent. This means that by utilizing these resources consistent power supply can’t be generated. Like the sun is not always at noon. Similarly, the winds aren't always blowing. Neither the demand is consistent, it varies throughout the day. So, How can we rely on these renewables?
That's where storage systems come into play. Imagine storing the excess energy when the sun is at noon, or when the winds are blowing at full speeds that can be used to reproduce electricity whenever needed. At this point, if you are wondering why can’t we simply use Battery Energy Storage Systems? Well, that's a fair point. Lithium-Ion batteries are booming these days, as per the US Energy Information Administration’s (EIA) 2020 report, the worldwide lithium-ion battery industry is expected to treble to $91.9 billion. But thing is that we have limited resources in this domain. They have significant environmental impacts and many techno-economic limitations. Also, Electric vehicles are the major consumers of Battery systems. So, using Battery storage won’t be cost-effective in the longer run, and neither it is sustainable. Therefore we need another medium of storage and here is when mechanical storage comes into play. The world has already realized the need for these unconventional storage systems and different companies/ startups are working on the design concept of an unconventional, efficient, sustainable, modular, and scalable storage system that can resolve the storage issue of the power sector and can make this shift towards renewables possible.
Thermal Energy Storage
The basic idea of thermal energy storage is to store excess energy in form of heat energy and to utilize this thermal energy whenever needed. Antora Energy a company founded in 2018, has come up with a design concept of Thermal storage in which the aim is to use the excess electricity to heat blocks of carbon so they glow red-hot like inside a toaster. This thermal energy is then delivered to customers as electricity or industrial process heat up to 1500°C, on-demand. In this methodology, Antora Energy has also cracked the process of converting back heat energy to electric energy. For which Antora has selected thermophotovoltaic cells. The main purpose of the thermophotovoltaic cell is to convert heat radiations to electricity, just like photovoltaic cells convert solar energy to electricity. But one of the major problems with the thermophotovoltaic cells is their low efficiency. However, Antora Energy has designed a thermophotovoltaic that operates with an efficiency of about 30 percent.
The design concept of Antora Energy is described in the following figure,
It is believed that this concept of Antora would be a major player in the decarbonization of heavy industrial processes which require process heat that comes from Natural gas boilers. The concept of Antora Energy is so concrete that even Bill Gates is backing this startup. In his 2021 book, “How to Avoid a Climate Disaster,” Gates wrote that the process of making things like cement, steel, and plastic is the single biggest contributor to greenhouse gas emissions worldwide.
Antora Energy has also raised a funding of $50 million. Also, Antora Energy was added to the “50 to Watch List” of Cleantech Group. Antora Energy can be a major player in electrifying heavy industry with thermal energy storage for zero-carbon heat and power. But for now, Antora is still a lab project. CEO Andrew Ponec said he doesn’t expect deployments to begin until late 2023.
Compressed Air Energy Storage (CAES)
The main design concept of Compressed Air Energy Storage (CAES) is to use the excess electricity to compress air, and this compressed air can be used to produce back electricity whenever needed. CAES has been operational in its conventional form for over decades now. The first CAES plant was a 290 MW power generation unit built in Hundorf, Germany, in 1978. But one of the major problems with this conventional design concept of CAES is the site feasibility. Because we need some underground caverns, where this compressed air can be stored. So, this limits the use of CAES. Another major problem with this conventional design concept is the rise in temperature during the compression of air, which ultimately leads to the low overall efficiency of the plant.
These two major issues of CAES have been well addressed by Augwind Energy, which is an Israeli technology company aimed to revolutionize energy storage by storing compressed air underground. Augwind Energy is working on the design concept of Air-Batteries, where Air is stored in underground tanks made of unique polymer material. Water is pumped into the system, which compresses the air, and as water is used to compress the air the temperature rise doesn’t take place because water also acts as a heat sink absorbing all the heat due to compression. Now, this compressed air is used to push back water to run a hydroelectric turbine to produce electricity whenever needed. In this process, the overall efficiency achieved is about 81%. So, the AirBatteries are modular, scalable, and can provide storage capacity with minimal environmental footprints. The following video describes the design concept of AirBatteries.
Flywheel Energy Storage Systems (FESS)
The next storage system on the list is Flywheel Energy Storage System (FESS), and its main idea is to store excess energy in form of kinetic energy in a rotating mass which is used to produce back power whenever needed. The major advantage of this storage system is that the supply is instantaneous, which is because you have to just make a connection of rotating mass with the shaft leading to the generator and you get the power output. Sounds easy, right?
But the one major drawback of FESS is the high self-discharging time. As FESS consists of a rotating mass, with time the speed of its rotation decreases due to friction offered by the surroundings. This means a significant loss of energy, which ultimately makes this whole system very inefficient or incapable of long-duration storage.
However, Amber Kinetics is a company that manufactures grid-scale kinetic energy storage systems (KESS) and they claim to be the only provider of long-duration flywheel energy storage. Amber Kinetics started its journey in 2008 and to date, Amber Kinetics’s fleet of installations has accumulated over 578,000 hours of run time and an installed capacity of 916 MWh around the world.
The Flywheel system of Amber Kinetics consists of a vacuum-sealed container in which Rotating flywheel mass is held with the help of magnetic levitation and special bearings that minimizes the friction. In these conditions, the Amber Kinetics design can serve a roundtrip efficiency of 86%. Such a system can be effectively used to meet the buffer load requirements or to handle energy imbalance by storing energy during off-peak hours and delivering power during the peak hours of load. The following video defines the concept of the design of Amber Kinetics.
Well, If you are still reading it, then Thank You. I hope you find it interesting and very informative. If you have any feedback, suggestions, or comments do share. I’m more than happy to hear.
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