How CO2 could be the future of energy storage?

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CO2 is widely recognized as the primary cause of climate change; however, what if this iconic greenhouse gas could be repurposed as a renewable energy source instead? If you can believe it, carbon dioxide may be an essential ingredient in the creation of a new environmentally friendly battery that can be rapidly distributed all over the globe. You won’t want to miss this if you have any suspicions that I’m simply trying to get a rise out of you. Would enormous CO2-storage tanks be able to solve our issue with energy storage? Let’s see if we can conclude this, shall we?

Would enormous CO2-storage tanks be able to solve our issue with energy storage?
CO2 is widely recognized as the primary cause of climate change

You may already be aware of this, but carbon dioxide is one of the most important greenhouse gases (GHG) in the atmosphere. More explicitly, CO2 is responsible for about three-fourths of the world’s total emissions caused by man. The natural presence of carbon dioxide (CO2) and other greenhouse gases (GHG) in our atmosphere insulate our planet. We must have this blanket, yet it seems as though it is becoming more cumbersome and is trapping an unhealthy amount of heat. Even though carbon dioxide is the obvious villain in this scenario, there is still a chance that it might have a happy ending. 

The use of renewable energy sources is one of the most effective tools at our disposal for combating global warming and lowering greenhouse gas emissions. However, the fact that it is intermittent lowers the amount of climate change it can help prevent. As a result, we need an energy storage system that is both cost-effective and durable to deal with its peaks and valleys. Carbon dioxide may be the answer we’ve been hunting for all along.

In June of this past year, an Italian startup company called Energy Dome successfully demonstrated the functioning of the world’s first CO2 battery on a pilot scale in the island of Sardinia. This remote location is producing a wealth of prospects in the field of renewable energy because of the abundance of sunlight and wind. Although the storage capacity of their demonstrated device was only MWh4, their first commercial scale plant will have 200 MWh, and it is anticipated that it will be online by the end of the year following the one in which it is built. After only two years of testing, the Energy Dome’s battery seems ready to store clean energy and send it all over the world for up to twenty-four hours at a time.

In addition to the recent financing effort of $11 million that the startup company undertook to commercialize its utility-scale long-duration batteries, the company has already signed a few contracts. For example, they intend to construct a facility with a capacity of 20 MW-5h for A2A, the second biggest utility company in Italy. Ansaldo Energia also hired them to work on developing energy storage systems in Italy, Germany, the Middle East, and Africa.

Using CO2 as a weapon against climate change certainly raises some eyebrows, doesn’t it? So, how exactly does it function? The technology behind the Energy Dome is based on a thermodynamic system with a closed loop. In the course of the charging procedure, the plant draws from the excess of renewable power provided by the grid. This operates a motor that draws carbon dioxide (CO2) from a large dome-shaped double membrane gas container, which is essentially a gigantic bladder. The gas is kept at the standard temperature and pressure in this location. After going through a turbo compressor and being pressured, carbon dioxide is converted into an extremely thick liquid. This liquid is then held in something like a fire extinguisher at ambient temperature at a pressure of 70 bar (1015 psi). The charging process is responsible for storing renewable energy as high-pressure liquid CO2. At the same time, the system can recover and store the heat generated by the compression in two separate thermal units. After the electricity has been discharged, the heat recovered is then used again in the process of turning the liquid CO2 back into a gas. This gaseous stream goes through an expander first, then powers a turbine, resulting in the generation of energy that is then sent back into the grid. In order to finish what has to be finished, the CO2 is taken to the dome, where the next charging cycle will begin.

Do not be concerned that carbon dioxide will escape from the system or that you will need to add large amounts of CO2 to it over time continuously. According to Energy Dome, there are no CO2 gas escapes. I got the opportunity to speak with Claudio Spadacini, the CEO of Energy Dome, and the following is what he had to say regarding the configuration of the system. 

When the system is first put into operation, we add CO2 to it; after that, we do it just once every 30 years. As a result, we do not continually utilize CO2. It works similarly to the refrigerator or the air conditioner in your vehicle; you just need to charge it once initially. And the carbon dioxide that we make use of is only the operating fluid of our batteries. -Claudio Spadacini

Their system will only need a few hundred tons of CO2 to get started but will not need any further gas once it is fully operational. This is a drop in the bucket compared to the amount of carbon dioxide our plants that run on fossil fuels produce yearly. It is not so much the CO2 that is consumed by the system that makes this a “green” system as much as it is the CO2 that is not created via the use of fossil fuels for the production of electricity. However, the fact that CO2 is even a factor in this at all lends an air of irony to the situation.

CO2 battery: Way more than a gassy speech

CO2 battery: Way more than a gassy speech
CO2 battery: Way more than a gassy speech

If you feel like you’ve heard this fundamental idea before, it’s probably because you have. A number of different gases may be used as storage media; CO2 under pressure is only one of them. Utilizing a conceptually similar method, you may make use of compressed air instead. It is possible to have systems that store energy as compressed air (also known as CAES) or as liquid air (also known as LAES), depending on how the air is compressed. Instead of employing a compressor to lower its volume, the second approach involves cooling air to a temperature of -196 degrees Celsius; this is one of the reasons why it is also known as cryogenic energy storage. If you’re interested, I have another video that covers the same subject.

So, how does CO2 compare to air for storing energy?

Let’s take a look at energy density as an example; this will give you an idea of how many kilowatt hours may be stored in the same amount of space. The data that can be seen on Energy Dome’s website indicates that the company’s CO2 battery packs have an energy density that is up to 11 times greater than that of CAES. After doing some research, I can confirm that they are, for the most part, correct. Even when the greatest value of CAES energy density stated in the literature is considered, the Energy Dome’s density is still six times higher. Because of this, CAES systems need very large storage areas, such as the deep salt caverns, in order to properly house the low-energy-density compressed air. These can only be discovered in certain regions, limiting the CAES’s expansion potential. On the other hand, compared to the Energy Dome system, the LAES can pack almost twice as many kWh into each cubic meter. However, in order for LAES to operate, the temperature in the room must be lowered to an absurdly low level so that air may be liquefied. In addition, in order to make electricity, you will need to bring the temperature of the liquefied air back up to room temperature. This extreme cycling of chilling and warming has a negative impact on the round-trip efficiency (RTE) of the process, which typically ranges from 45 to 70 percent. The CO2 utilized in the Energy Dome system, in contrast to the air used in LAES, is kept at the same temperature as the surrounding air, which decreases both operating costs and energy penalties. Compression and evaporation are the only two processes involved in the design of the Energy Dome, hence its construction is rather straightforward. This more efficient design, in conjunction with lower operating temperatures, helps to decrease energy losses, ultimately resulting in an RTE that is anywhere from 75% to 80%.

CO2 has the potential to be a viable alternative to batteries that are based on metals, and it does it in a more effective manner than air does when it comes to storing energy. According to a press release issued by Energy Dome, their product would be half the price of a lithium-ion battery of comparable size.It would seem that after their 25MW/200MWh facility was operating at full capacity, they anticipated that the levelized cost of storage (LCOS) would be as low as $50 per megawatt-hour of energy that was stored. At this time, we will have no choice but to put our faith in them about that number. Nonetheless, Lazard said that they projected the LCOS of a 4-hour 100MW/400MWh lithium-ion battery system to fall somewhere in the region of $131-$232/MWh. The LCOS for LAES may reach up to $300/MWh, making it much more expensive than LAES.

I can already make out your voice. What is pumped hydro storage, or PHS, for short?

Aside from the fact that they are the biggest long-duration utility-scale power storage systems in the world, they also have a lifespan of up to 150 years. However, the price of their LCOS is now set at $186/MWh, which is far more than what Energy Dome is providing. In order to determine whether or not the cost of Energy Dome will wind up being more than anticipated, we will need to wait at least until the end of 2023 or the beginning of 2024.

In addition to being one of the most sought-after fugitives in the world, the essential component of Energy Dome is far more environmentally friendly than the raw materials used in conventional batteries. For instance, the extraction of one ton of lithium requires the use of a total of 500,000 gallons of freshwater. Nickel is another important component of the cathode, and the mining of nickel is the activity that produces the largest carbon dioxide emissions. Regarding cobalt, around 70% of the world’s supply originates from the Democratic Republic of the Congo (DRC), which has a terrible track record regarding the use of forced labor, child labor, and safety.

Steel, carbon dioxide (CO2), and water are the only components required for Energy Dome batteries; hence, the CO2 battery may be constructed using off-the-shelf equipment procured from the preexisting supply chain. Because of this, the system is very easy to scale. For instance, the oil and gas sector has adopted their compressor as the de facto standard for such equipment. This may provide Energy Dome with a competitive edge.

“I don’t see any type of difficulty in the supply chain,” the person said. The fact that this technology is based on an existing industry gives us a significant competitive edge. Vessels, heat exchangers, a compressor, a turbine, and a generator motor all belong to this industry, which is an industry that can be found almost everywhere. is present in the region of North America, is present in the region of Europe, and is present in the region of the far East. Therefore, I do not perceive any limitations, such as many other technologies. A wide variety of other technologies face bottlenecks in the supply chain. -Claudio Spadacini

The passage of time is another disadvantage of lithium-ion batteries. Most systems reach their maximum capacity after around six hours, for the greatest possible savings in terms of storage costs. Evidently, it is not enough to serve as a backup for the system during prolonged times of low output from renewable sources of energy or throughout the night. The electricity dome would come in handy in this situation due to the fact that its CO2 battery could provide energy for up to 24 hours straight. In addition to having short-term limits, the lifetime of lithium-ion batteries is at most 15 years due to the fact that their performance decreases with increasing numbers of charging cycles. On the other hand, the Energy Dome system is designed to survive for as long as thirty years. Another advantage offered by the Energy Dome technology is its adaptability. They can change the size of their batteries and meet various storage needs by using a modular design strategy.

What is bursting the Energy Dome bubble?

It seems that this Italian business has successfully combined two tasks into a single carbonated solution. making use of the same gas contributing to some of our issues to develop a potentially useful long-term energy storage alternative. There are certain obstacles to overcome, despite the fact that it seems quite promising. An energy dome, sometimes known as a dome, is an above-ground inflatable gasholder that stores carbon dioxide at the same pressure as the surrounding air. In contrast, CAES stores pressured air below. In the words of its chief executive officer, Claudio Spadacini, it is “just like a CO2-filled tennis-court bubble.” The problem that may arise is one of space. How well does this system perform when increased in size? However, he did reveal that one of the Energy Dome’s drawbacks compared to lithium-ion batteries is its limited space.

“Our technology is not the most space-efficient out there in terms of its size. This is the only drawback we have seen compared to lithium ion batteries. The amount of land required by the CO2 battery is around seven to eight percent of the amount required by the solar PV plant, which should provide us with the electricity we can store. -Claudio Spadacini

Even while space isn’t much of an issue, technological difficulties might potentially burst the Energy Dome bubble. According to a specialist who studies energy systems at Loughborough University, the heat exchangers that the Italian firm is now employing may have trouble performing effectively throughout the course of the expected lifespan of the plant. This indicates that they may be required to put in some more effort in order to reengineer and modify the technology, which may cause their scale-up to be delayed. As mentioned before, Energy Dome is striving to achieve an RTE of between 75% and 80%. Prior research that evaluated the performance of a plant that was quite comparable to the current one looked to be less positive. According to the findings of Chinese experts, the optimum level of performance for both the compressor and the turbine was at around 67%. In light of this, Claudio has the following to say:

Consequently, at this point, there were a great many individuals who did not believe in us. It went by much too quickly. So, we are making the claim that we are 75% effective, but there are still a lot of individuals who don’t trust us. They assert that it is not doable. But now, we have something to deliver on our promise. We want to keep our word in all that we say and do. Therefore, we set out to provide evidence that supports our claims. -Claudio Spadacini

This has been the focus of Energy Dome’s efforts with the pilot facility. If we assume that Energy Dome will achieve an RTE of between 75 and 80%, this indicates that they will waste between 20 and 25% of the energy they put into their battery. On the other hand, the RTE of lithium-ion batteries may reach up to 90%, indicating that you only lose 10% of the energy you put into the battery. If you do the arithmetic, you’ll realize that the Italian start-up is wasting 2.5 times as much energy via the RTE as the other company. On the other hand, this is not something that should inherently cause us concern. Even the biggest pumped hydro energy storage systems in the world are only able to attain an efficiency level of approximately 80%. To put it another way, batteries still have the upper hand when it comes to short-term energy storage of up to six hours, but when it comes to long-term energy storage, the Energy Dome holds its own rather well. Claudio did, however, bring out an important issue that should be recalled: since lithium ion batteries gradually lose capacity over time, it is important to keep this in mind. Systems that store energy like the Energy Dome and Pumped Hydro do not lose any of their potential storage capacity over time.

When it comes to innovations with a longer lifespan, direct rivals all over the globe are pushing on the throttle, and they may soon catch up with the competition in Italy. For instance, the United Kingdom-based company Highview Power has said that the $50/MWh goal may be met by its 100MW wind-powered LAES by the year 2030. Echogen made the same claim on the other side of the pond, except that they’ve discovered a formula for thermal storage that includes sand, ice, and supercritical CO2.

In the case of the Energy Dome, we won’t have to keep waiting for an excessively lengthy period of time to find out how well it operates. Not only did they complete their pilot test in a short amount of time, but they are also taking a highly proactive approach to their next initiatives. Their high level of trust comes in part from the fact that they have streamlined their supply chain and the parts they use.

“…because our product is a standardized product, and we will repeat it. Just by economy of scale, we will be able to cut that delivery time below one year, including construction, in less than a couple of years.” -Claudio Spadacini

What is bursting the Energy Dome bubble?
What is bursting the Energy Dome bubble?

Although the claimed speed seems to be impossible to achieve, this would not be the first time that Energy Dome has increased its turbo speed. It is thrilling to think that Energy Dome may be able to redeem CO2 as a climate savior, and the company seems to know what it is doing. Nevertheless, until we see the actual cost of their first plant operating at commercial scale, it is in everyone’s best interest to dial down the hype machine. It’s possible that this won’t be the magic solution to the problem of climate change, but it might lessen the demand for fossil fuels as a backup source of power for renewables, and it could cut down on the amount of mining needed for metallic batteries. Regardless, CO2-based storage systems will not be able to fully replace lithium-ion batteries, which will continue to be the most cost-effective alternative for lower-scale applications with shorter run times. So, a mix of the two technologies might be the best choice for the environment in the years to come.

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