Batteries

Did you know Alessandro Volta is credited with inventing the first functioning battery, called a voltaic pile, in the year 1800?! There are several types of batteries that are used in everyday life and across many industries, and batteries are becoming increasingly significant for both renewable energy and electric vehicles, two crucial innovations in the fields of climate science and clean energy.

All batteries, whether they are in your car or smoke detector, function with the same basic idea: they store chemical energy and convert it into electrical energy (aka electrochemistry). A battery does this with an electrochemical cell, which contains two terminals called the anode and the cathode and a chemical medium called an electrolyte that lies between the two terminals. The cathode and anode are separated by a semi-permeable barrier. The battery is connected to an external circuit, which is the transmission line that gives energy to the electrochemical cell through electrons. Both an electrochemical cell and an electric circuit are required to store and release energy in a battery. Electrons move through the circuit and ions move through the electrolyte. As the electrons move from the cathode to the anode, the chemical potential energy of the electrolyte increases, which charges the battery. If the electrons move in the opposite direction, from the anode to the cathode, this energy is converted into electricity in the circuit and the battery runs. When the battery is fully charged, the circuit can disconnect and the battery is ready to be used at a later time.

Electric vehicles (EVs) are rising in popularity, and with that, there is also increasing demand for highly efficient batteries to power these cars and trucks. Instead of an internal combustion engine that requires gasoline to run, EVs are charged with electricity that is stored in a battery, and an electric motor moves the vehicle. EVs are desirable because they produce no tailpipe emissions. Emissions may be generated at a power plant in order to charge EVs with electricity, but as renewable energy continues to develop, EVs will become virtually emissions-free. Batteries also make EVs preferable because they don’t require gasoline, so there are added savings after the initial purchase: driving a battery electric vehicle can save drivers about $700 annually in gas money.

Battery technology is also expanding in order to provide an energy storage solution for renewable energy sources (check out our pages on renewable energy to learn more about this type of energy!). Because the sun is not always shining and the wind is not always blowing, there is a push to store any extra energy that is generated from renewable sources. Batteries connected to renewable energy generators store excess energy to be used on days when renewable energy cannot be created because it is cloudy or not windy.

In Kaua’i, Hawaii, the AES Lawa’i Solar Project has a 100 megawatt-hour battery energy storage system paired with a solar photovoltaic system. Image source: AES Distributed Energy

Battery storage for renewable energy is growing rapidly. According to the U.S. Energy Information Administration (EIA), the number of solar and wind generation sites co-located with batteries has grown from 19 in 2016 to 53 in 2019, and an additional 56 facilities with renewable energy and battery storage are slated to be operational by the end of 2023. By 2025, there will be an estimated 7.5 gigawatts of energy storage in the U.S. Single batteries are also reaching a size (about 200 megawatts) that allows renewables to replace typical gas generators. As these trends continue, battery storage will be a key player in switching from fossil fuels to renewable energy.

Lithium-ion Batteries

Lithium-ion batteries are the most common type of battery found in both electric vehicles and renewable energy storage systems, and they can also be found in laptops and cell phones. First created in the 1970s, lithium-ion batteries later became popularized by Sony in 1991 with their video recorder. In a lithium-ion battery, the anode and the cathode contain lithium ions, and the same movement of ions between the anode and cathode occurs.

These batteries are unique and popular because of their high energy density, meaning they can store a lot of energy in a smaller battery. Lithium-ion batteries are also able to power high-powered applications, such as EVs, by delivering up to 3.6 volts, which is 3 times higher than other batteries such as nickel-cadmium and nickel-metal hydride batteries. They are also more lightweight and compact compared to other rechargeable batteries.

A surge in lithium-ion battery production over the past 10 years has led to an 85% decline in battery prices, making makes the production of electric vehicles and renewable energy storage economically feasible.

Environmental Impacts

While batteries are crucial to reducing CO2 emissions and combating climate change, they do not come without their flaws. Mining lithium requires 500,000 gallons of water per metric ton of lithium. In addition, lithium-ion batteries are incredibly hard to recycle, although there are companies working to do so! Lithium cathodes cannot be reused because they degrade over time, so once the battery needs replacement, which is usually required every 8 years for EVs, that lithium is lost. Newly mined lithium is necessary for every battery built. The Union of Concerned Scientists also found that manufacturing an electric vehicle produces about 15% more emissions than its gas-powered counterpart because of the energy required to produce lithium-ion batteries, which are still predominantly powered by fossil fuels. These emissions will decrease as renewable energy grows, but for the time being, battery production creates its own emissions.

Lithium-ion batteries are currently the most popular rechargeable battery in the industry, but there are constantly new technologies being explored and developed in order to find the most efficient, long-lasting, and environmentally friendly solutions. A few examples of emerging battery technologies include:

• Redox flow batteries use fluids to store electrochemical energy. The electrolytes that are found in a typical battery are located in tanks outside of the electrochemical cell, and the solution is pumped into the cell.

• Compressed air energy storage converts electrical energy into highly pressurized condensed air which can be stored, and then released when needed to power a turbine and produce electricity.

• Gravity-based batteries use principles of physics to store energy as gravitational potential energy. Large masses are moved higher as electricity is generated, and that electricity charges the battery and becomes stored as gravitational potential energy. When the energy is ready to be used, the weights are lowered, which converts the gravitational potential energy into kinetic energy.

It will be exciting to see how battery technology grows and evolves as both renewable energy and EVs continue to lead the energy transition!

The sizes of the batteries depicted in the images above are largely dependent on their varying uses. These images show batteries ranging from those used in electric vehicles to single-family houses and industrial buildings.

Image 1: Standard all-electric vehicle battery. Image source: U.S. Department of Energy; Image 2: Tesla Powerwall. Image source: Dennis Schroeder; Image 3: 4 Megawatt battery installed at Schweitzer Engineering Laboratories. Image source: UniEnergy Technologies