Introduction           

The topic of our nation’s energy and how we should get it has been hotly debated in politics and the news. It is only getting hotter as more and more research about global warming links energy to climate change. America is currently very dependent on oil, gas, and coal for our energy needs. These forms of energy release carbon dioxide as a byproduct. But we now have the technology to switch to other energy forms that do not emit carbon dioxide and can help reverse global warming.[1] There are three primary carbon-free ways to collect energy that I will talk about in this blog: solar, wind, and nuclear. I am convinced that solar is the best way to create our electricity because it is renewable, the fastest developing technology, and the cheapest. However, this energy needs to be stored. The sun and people are not on the exact same schedule for solar energy to properly power the grid, we must store it and then release it back into the grid during times when the grid needs more energy than solar can produce at that time.[1] But how should we store this energy? Currently, batteries are the most developed and popular form of storing solar energy, then hydroelectric storage and supercapacitors, and gravitational potential energy. My research has led me to support gravitational potential storage as the best form of storing solar energy because it has a high efficiency of energy stored to energy produced, and it is less expensive than other forms of energy storage. It is being developed in multiple different prototypes by different companies. For the remainder of this blog, I will argue and explain how solar energy stored via gravitational potential energy has the capability to be the future of a sustainably renewable energy grid.

The Current Source of Our Energy

Currently, in the world, we get the majority of our energy from oil, coal, and natural gas. Which science shows leads to the carbon emissions that are causing global warming. If we want to keep our earth habitable we need to find a way to get the energy we need without pumping pollutants like carbon dioxide into the air. This is where sustainable forms of energy come into play. Solar, wind, and hydroelectric energy are all forms of renewable energy that with new developments in technology are now capable of being alternatives to oil, gas, and coal. In 2018 renewable sources made up approximately 15% of the total primary energy and over 20% of electricity generation.[2] It did this while producing 0% of the carbon emissions while oil, gas, and coal produced 100% of them. Oil companies know that there is a change starting to come and they have nearly doubled their investment in renewable sources of energy generation.[2] They specifically have begun to invest heavily in one form of renewable energy: solar energy. They have increased their investment in solar energy from 500 million dollars in 2015 to just over 1 billion dollars in 2019.[2] Solar energy makes up 48% of the new power-generating technology installed in 2021.[3] The impact of all this investment is that we are seeing a change in how our nation will soon be switching to reliance on solar. As the old fossil fuel energy plants start to break down they will be replaced by solar plants. As time continues to pass the 15% of energy and 20% of electricity will continue to grow as more and more solar plants are built and fewer and fewer fossil fuel plants are. But why are the oil companies choosing to invest in renewables and specifically solar? Well, building solar is now cheaper than building a new power plant that uses fossil fuels.[4] Not only is it cheaper right now solar has dropped to 1% of its original price in the past 30 years and will continue to drop as we develop better and better technology.[4] In such a capitalistic and competitive market whatever is cheapest will get these companies’ attention. If they can get a competitive advantage by building solar and getting the same amount of energy for less, obviously they will do it. This means that their already increasing investment will continue to grow as solar becomes to make more and more economic sense with it’s continually shrinking price. 

The largest issue facing solar energy is storing it. It is already cheaper to make and produce than fossil fuels. The main advantage that fossil fuel plants have is that they can be operated to produce energy at any time. This means that energy companies can create more or less to match the energy demand on the power grid. Solar energy does not have that convenience. It peaks around noon, dips around peak hours of demand, and is useless at night. Since the production and electricity demand of solar energy do not match, energy companies have to store the energy as it is produced and release it when it is needed. But because conventional electric generating technologies do not need to be stored there has been very little research and development of large-scale energy storage. Rapid progress is now underway in creating large-scale affordable energy storage. The amount of new storage that is being applied to the energy grid is projected to increase by 15x, and the amount of funding going towards building energy storage is projected to increase by 3.5x. [5] Such a rapid increase in storage shows that we have the capability to create enough of it that we can switch to solar energy in the near future.  

Other forms of energy production that produce no carbon emissions are; wind and nuclear. The wind is another form of energy that is becoming popular making up 14% of new power-generating technology installed.[3] It is now 4.5% of its original price 30 years ago making it similar to solar in the fact that it has a decreasing price.[4]The difference in growth is indicative of a recourse-based technology. For a wind power plant to make economic sense for a company to invest in it, there have to be favorable wind conditions in that area that allow for the turbines to be producing energy a large portion of the year. But these areas of ideal wind are not widespread and the areas that do exist are typically far away from where the energy is needed. For example, one of the best places to get wind energy is from turbines built on the ocean. Therefore, the source of our energy will be very far from where it is actually needed. This means that the grid would have to be expanded costing extra money. Nuclear is another form of energy that does not emit carbon dioxide plus it avoids issues that solar and wind power face. But it does face its own set of challenges that make it less effective and less sustainable than solar energy. The main issue is the radioactive waste that is a byproduct of producing energy. While newer-generation nuclear reactors are reducing waste there will always be a non-disposable byproduct. [6] Radioactive waste is even worse than carbon dioxide emissions because managing the waste is already starting to become an issue with nuclear power only making up around 5% of energy production.[2] If we wanted to use enough nuclear power to replace all fossil fuels we would have no way to store all of the dangerous waste that is a byproduct.

Forms of Energy Storage

The most popular form of storing energy currently is rechargeable batteries. Due to them currently having the most development in their technology and therefore most convenient. The two main forms of rechargeable batteries are lithium-ion and lead batteries. They are used in most electronic devices and now they are making their way into electrical storage. The main issue with this style of storage is that it is not fully renewable. It requires either lithium or lead to make the battery which we have to mine from the earth. The process of mining for these materials emits carbon dioxide. So as we switch to solar energy, the amount of emissions from mining will increase as we need to make more batteries. Not to mention it is also a limited resource on earth. As we continue to mine and lead or lithium becomes scarce we will run into the same issues that oil has; fluctuations in price based on supply and a constant need and search to find more of it. Some people might argue that since the lead in the lead acid batteries is recyclable we could just keep reusing the same lead and not have to keep mining. The main flaw in this argument is that the demand for batteries keeps going up and it takes some batteries a decade or more before they need to be recycled.[7] The lead we have mined now is going to be in use so as the demand for more and more batteries increases we will still need to mine new lead to meet the growth. Lithium-ion batteries have another issue as well. In a presentation by Christophe Pillot, a partner and director of Avicenne Energy which is a battery consulting company that has been around for the past 20 years. He discusses the future of batteries. When talking about batteries he is very positive about the market and thinks that the lithium-ion battery market will explode. But he does acknowledge that “Their further development has for a long time been slow because of a low cycle efficiency and safety issues: High chemical reactivity and a low melting point enable strong chemical reactions, even explosions. In the charging-discharging process, lithium metal can form dendrite and accumulate on electrodes. The growing lithium dendrite could puncture the separator and result in an internal short circuit… In case of overcharging or short-circuit (contact between anode & cathode) a chain reaction starts -> heating & gasing -> fire”[8] This quote is explaining how lithium-ion batteries can possibly explode from charging and releasing energy. Something that they would be doing daily as our energy storage. Not only would the batteries blowing up cause a loss in human lives from the explosion it would also result in a power outage on the grid because we would have nothing to store the energy. This would require the entire storage system to be built again, an expensive and time-consuming process. A battery already exploded on a 787 plane and Boeing had to ground all of the planes and fix it. Another event that could cause an explosion is the weather. In Florida, this summer after Hurricane Ian many electric cars exploded after they became waterlogged and the batteries corroded. [18] Grounding planes would cause an airfare issue for a while and the exploding cars required lots of attention from firefighters. If this were to happen to the energy grid it would be devastating for everyone involved and there could be even more casualties from people having to live without any form of electricity for an extended period. While batteries may be the most developed form of storing electrical energy we have at this moment. It is not the best option because of the fact that it is not truly renewable and it has the chance of completely failing and taking human lives in the process. 

            Another technology that is in use is storing electricity with hydroelectricity. It works by taking the solar energy and using it to pump water upwards into a higher elevated reservoir. Then when the energy is needed, releasing the water through turbines and using the energy generated from that to power the grid.[1] It is a very efficient process and works very well where there is a natural connection between a higher and lower reservoir of water. For example, there is a project to turn the Hoover Dam into a large hydroelectric storage battery. But there are issues with hydroelectric storage. One is that it can only work in a select number of areas on earth. There are very few areas that naturally work and most of them are already being used for hydroelectric storage and we still need more storage. Environmental groups and people living near these operations are also not keen on hydroelectric storage. They are worried that because these storage facilities need to pump the water back and forth. This will affect the flow of the rivers. This can be devastating to the wildlife that lives in the river and also potentially cause flooding making it a risk to those who live near these rivers. Others may argue that we can just create man-made reservoirs. That way we have more places to build them and there would be no wildlife living there so environmental impact would be insignificant. While this is a very true point there is a major issue facing it. The ability to finance this much hydroelectric storage. The Hoover Dam project which is taking an already-in-use dam that already has the technology installed to get energy from when water flows through it cost 3 billion dollars and 10 years just to build the infrastructure to pump it back up.[9] If we wanted to get enough man-made reservoir systems built to store all of the energy we need it would cost an exorbitant amount and take more time than we currently have to save our planet from global warming. Even though it does work at a high efficiency, it is too much of a financial challenge as well as an environmental issue to be the optimal solution to the our nation’s electricity storage problem. 

The last form is by storing the energy with supercapacitors. A capacitor is anything that is two conductors that are near each other but energy does not flow between them. A supercapacitor is what you would expect, the same thing as a regular capacitor but sized up to store even more energy. They are very durable and last a long time before needing to be replaced. Regular capacitors are very safe and tested. Even I used one in high school physics class. Supercapacitors, especially to the scale needed to store enough energy to be used in the grid, are far less tested than the other forms of energy storage. Only two types of supercapacitors have even been tested and neither one of those was meant to store enough energy to support the grid.[10] Those in favor of capacitors may argue that a capacitor’s main job is to hold energy and then release it when needed. It makes sense that we would use them to store solar energy. But the issue is that the largest capacitor that has been successfully tested was made for cars and military systems, two things far smaller than the amount that would be needed. Another issue is that their effectiveness varies based on the temperature.[10] Energy storage being affected by temperature is another way to continue the issues we have had in Texas in winter 2021 and the blackouts that California has had over the past few summers. The small scale that current supercapacitors are at; combined with the variation depending on temperature means that it should not be used to store our energy for the grid. 

Gravitational Potential Energy Systems

            Here I will explain why gravitational potential energy is likely the best option we have to store significant amounts of electricity. With the technology we have now it has already proven to be the most efficient way to store energy with some systems being able to store energy at 90% efficiency while boasting a lifespan of up to 50 years.[11] This means that we can save money by not needing to build extra solar panels to get the amount of energy we need because gravitational potential energy is so efficient at storing it. Gravitational potential energy storage typically operates for about 50 years compared to batteries which last around 5-10 years. [8] Having to build 5-10x less frequently due to gravitational potential energies system durability saves a large amount of money. Furthermore, creating the electricity from gravitational potential energy is also cheaper. According to preliminary reports from the gravitational potential storage company Gravitricity, their system can cost less than half the price of each megawatt hour than lithium-ion batteries. [13] This is a great incentive that will encourage companies to move towards gravitational potential as their preferred way to store energy. All companies love saving money without having to lose anything and that is what gravitational potential energy is giving them the opportunity to do. A benefit that gravitational potential energy has over hydroelectric power is that it can be built anywhere as well. This means that the storage facilities can be built right next to the grid that needs power or solar energy system making it allowing for easy and efficient transitions into the grid. 

            With all of its benefits, many companies are working to develop their own version and get into the market. One of the new companies is Energy Vault which uses 35-ton bricks made from recycled materials which an AI-controlled crane raises and lowers to store and release energy when needed. This system manages to get an 80-85% efficiency but it can store 27 GWh on only 14 acres of space.[12] There is another exciting start-up company that I have already mentioned called Gravitricity. This company has a similar idea of lifting up blocks with excess energy and then dropping them when energy is needed in the grid. This system uses 500-ton bricks which require a much larger foundation so the system is designed to be used in abandoned mines where there is already some infrastructure for it. So while it may not be able to be built everywhere, there will be a lot of abandoned coal mines appearing in the future once solar starts to dominate the market, and then they can turn the now abandoned mines into places to store energy. The storage will also be underground so that there is still room above the ground for solar panels. This makes extremely efficient use of the area. Both of the companies systems have less than half of the cost of what it takes lithium-ion batteries to store the same amount of energy.[12,13] This is very important as more storage development occurs; the price tag to create each kind of storage will greatly influence investors in a capitalist market like America.

            Naysayers may argue that there are very few actual gravitational potential storage systems set up and it is still a technology in development. How could we rely on it for our energy grid? This is a very good question and they are right, it is still in development and very new compared to technologies in batteries and even hydroelectric. Even though the systems themselves are new, the science behind them is not. Gravitational potential energy has been known by humans for far longer than they have known about lithium-ions, lead acid, and hydroelectricity. Meaning developments in gravitational potential energy storage are coming from applying science we already know. However for technologies like lithium-ion batteries research and then trial and error must occur for every new development. It typically takes 10-20 years to commercialize a new breakthrough and even Christophe Pillot admits that “The research and development in this industry is very long and time consuming.”[8] However, energy vault was a company that was founded in 2017, and by 2020 they had their first system up and running in Switzerland.[12] Gravitricity follows this face pace as well, with them planning the first model of their system in 2019 and they are planning on having their first system up by 2023.[13] This speed in development and construction shows how even though it at present may trail batteries in development and readiness at the present, it will not be long before this technology surpasses batteries and hydroelectricity as an effective and efficient energy storage device. 

Solar and Gravitational Potential Energy is The Future

            Our nation faces a large decision ahead, with the transformation of our energy system on the horizon. There are arguments for all sides of this debate and they are all valid. But the best possible solution for our environment seems to be to transition to solar. It has a low and constantly decreasing price, it gives off no carbon emissions. Most importantly its largest issue, storage, is clearly fixable in the near future with new developing technologies. Specifically, gravitational potential energy because it is the best option for addressing the storage issue. While batteries may be convenient to use now; their development is slow, they are not renewable, and they are more expensive. Hydroelectric storage is another alternative that is possibly good in small amounts but due to its environmental impact and the limited number of places where it can be effectively installed. But it is not able to meet the entirety of our storage needs. Supercapacitors are an alternative solution but due to the current development and the variation based on the weather, it is not dependable enough to be the answer. We need gravitational potential energy storage to be developed quickly as we expand our grid with low-carbon-emitting renewable energy sources. Gravitational potential energy is rapidly developing with multiple companies developing systems, it is cheaper, and it has no environmental or safety drawbacks.

Bibliography:

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