Charge It!

There are many things in life which we are only aware of when they don’t work — including batteries. We all know the feeling where you are using a device, be it a phone or computer, only to realize that the battery is low and that you suddenly have to find somewhere to plug in (presumably, so that you can continue to procrastinate from doing your assignments by spending just 10 more minutes on Instagram, Youtube, or the Student Movement). This is just one example of how important batteries are to our modern world. The very possibility of portable electronic devices depends on battery technology, and as we continue to move towards a renewable energy future, batteries and all types of energy storage will become ever more important. As such, let’s take a few minutes to talk about energy storage: How do the main current energy storage technologies work? How are they used? Why is battery technology so important? And what are current problems that we are facing with energy storage and batteries?

So, how do energy storage technologies, such as batteries, work? The big picture is that some forms of energy are easier to store and are more stable, while others are much harder to store and tend to decay away or dissipate into the environment. For example, electrical energy (the flow of electrons through wires), is extremely difficult to store. This is because as electrons move through a wire, they tend to bump into atoms in the wire, turning the electrical energy into heat, or thermal energy. As such, all batteries and energy storage convert energy that we don’t need to use at the moment into another form that is more stable, which can then be converted back to be used later. Several of the most common types of energy that we store are chemical energy (what is in the batteries our devices use), gravitational energy (with systems like pumped-storage hydropower, which we will discuss later), and thermal energy (where we heat up a reservoir of material, and then try to contain the heat to be converted back to electrical energy later). So while batteries are the energy storage technology we are most familiar with, there are also many others.

Given this information, why do we need so many different types of energy storage? How are each of them used, and why is battery technology so important? Battery technology is important for two primary reasons: portability, and load balancing. The reasons why we need portability are fairly obvious, as we don’t want to have to carry around generators in order to use our phone or computer; the need for load balancing, however, comes from our increased usage of renewable energy sources like wind and solar. The wind isn’t always blowing, and the sun isn’t always shining, so we need to be able to store excess energy produced for later. These different functions of battery technology are exactly why we need many different types, because they all have a very different range of situations where they are useful. For example, the chemical batteries are almost perfect for anything that is portable, as they can be made lightweight, are easily charged and discharged, don’t have any moving parts, and last longer without maintenance. However, chemical batteries are often more expensive than other alternatives, and while there are types of chemical batteries (eg. flow batteries) that are better suited for large scale electrical grid storage, they still require, as the name implies, often much more artificial chemical manufacturing than some of the other storage systems that are being developed, causing them to be more expensive, as well as making them harder to recycle once they reach the end of their lifetime (as some of the chemicals in them are toxic, and need to be disposed of specially).

Pumped-storage hydropower is most useful for solving a slightly different problem: long term storage of lots of energy. Essentially, pumped-storage hydropower can be thought of as a two-way dam. Near a body of water that is on some lower ground, there is a pumping/generating station that is connected to a closed off water reservoir that is high up above the pumping station, possibly on a hill. When there is excess power in the electrical grid, the pumping station spends that excess power pumping water into the reservoir, and when there is more electrical demand, the pumping station turns its electrical pump into a generator, allowing gravity to pull the water down through a turbine, generating electricity that can go back into the electrical grid. This is of course, a massive structure, and so is only really useful for electrical grid scale systems, being completely impractical for anything that an individual could ever use. However, pumped-storage hydropower is cheaper per amount of energy stored compared to batteries, and also doesn’t have many of the environmental problems that chemical batteries have, meaning that there are certainly situations where it is the better choice.

The third primary type of energy storage that is used is thermal energy storage. This type of storage is similar to pumped-storage hydropower — it is only really practical for large scale systems — but it is quite different in how energy is stored and released. With pumped-storage hydropower, the pump and generator can be switched between rather quickly, so large amounts of energy can be stored and released as needed. Thermal energy is quite different. With thermal energy systems, energy is usually harnessed using one of two systems: boiling water to produce steam to spin a turbine, or by absorbing the light that the heated object emits. In the systems that boil water to create steam, heating the heat storage material with electricity, which would then be stored to boil steam and then ultimately spin a turbine, would be extremely inefficient, and so these systems are usually paired with electrical generation facilities that work using heat anyway. For example, concentrating solar-thermal power. These solar power plants focus sunlight onto a receiver which then heats up to incredibly hot temperatures. While they are often used to boil steam immediately, the thermal energy can also be stored for later use. But, with systems that heat hot objects, often liquid metals, those metals release their heat as light rather slowly, and as such, these systems are best suited for situations where energy is needed to be released over long periods of time, and so work best when a low level, but consistent output is desired.

While each of these technologies have individual problems, there are some important issues that are common to all energy storage technologies. The most important of these is efficiency: whenever you convert energy from one form to another, there will always be some waste energy that is lost. This makes energy storage much more inefficient than just producing energy as needed, since energy is lost both during charging as well as discharging. As such, while a great deal of progress has been made, there are still many scientists working to make even more efficient energy storage. However, if we think about all of the potential that renewable energy sources have, how the sun is pretty much just constantly throwing free, practically unlimited energy at us for us to harness through both the light, as well as winds, which are driven by the sun’s energy, waste to charging and discharging batteries and other energy storage system is not much of a problem. After all, as solar panels and other renewable energy sources become ever cheaper and cheaper, it will become all the easier to simply generate more power. That is why renewables are nice, they don’t run out. Renewable energy generation of all kinds are constantly becoming more efficient and less costly, and as such, since renewable energy sources are very scalable (it is really easy to just put down another set of solar panels) the inefficiency of storing energy will become less of an issue as we become capable of generating more and more renewable energy.

The continued development of energy storage technology is essential for humanity as we move towards a green future. As we depend more on renewable energy, and more technologies that still depend on fuels, such as cars, become electric, we will need much improved battery technology. For chemical batteries, we need improved efficiency (so that less energy is lost from charging), improved lifetime and recyclability (so that we aren’t doing as much ecological damage from having to dispose of batteries), as well as better rechargeable large scale chemical cells. We need improved thermal and hydropower energy storage, so that the energy produced by renewable sources can be saved for when it is most needed. There are many other potential directions we could go in, from using compressed air to making solar fuels directly in solar panels which can then be used to later produce energy, or what is more likely, a wide range of different solutions. But no matter what directions we go, batteries and energy storage technologies will be central to our journey to preserve our planet.