Renewable energy sources like solar and wind are intermittent in nature, only usable when the sun is shining and wind is blowing. To compensate for the times when solar and wind are down, electric companies have to balance with other energy sources, usually natural gas, or coal, or other. The intermittency of renewables has been the greatest challenge in adopting cleaner energy sources. To solve this barrier, different viable solutions have been researched including electrical energy storage, which includes battery storage.
Electrical energy storage technology is the process of converting electrical energy into a storable form saving it in various mediums so that the stored energy can be converted back into electrical energy when needed. One of those mediums are rechargeable batteries, which is one of the most commonly used type of electrical energy storage.
A battery storage system consists of several electrochemical cells connected to produce electricity with a desired voltage from an electrochemical reaction. There are different types of batteries based on their chemical reaction: lithium-ion, lead-acid, sodium-sulfur, and nickel-cadmium among others. A battery storage installation can provide today around 4 hours of electricity. However, picking a battery storage system is not easy as some chemistries work better than others in certain environment; but based on a report by the U.S. Energy Information Administration from 2018, lithium-ions batteries represent “more than 80% of the installed power and energy capacity of large-scale energy storage applications”.
The value of battery storage and electrical energy storage in general is that it alleviates the intermittency of renewable sources for power generation, solves remote and vehicle load needs, and improves power reliability by reducing electrical energy import during peak electrical demand periods.
For years, low cycling times and high maintenance costs were considered the main barriers to implementing large-scale facilities. Not anymore, renewable energy and battery costs are both falling and pairing both of them has become cost competitive. This July in California, officials will approve a deal for a massive solar farm backed by one of the world’s largest batteries at a cost of 2 cents per kWh for the solar power and 1.3 cents per kWh for the battery. That is cheaper than fossil fuels. And according to Bloomberg, utility-scale cost for lithium-ion batteries has fallen by 76% since 2012 and by 35% in just the past 18 months. This drop in cost has prompted several projects across the United States, expecting to triple its utility-scale battery storage power capacity with 1623 MW of new additions to go online by 2023.
Furthermore, batteries do not just enable the energy transition toward renewable energy; but they are triggering the revolution in vehicles as well. There are 3 million electric cars on the roads around the world today; and by 2030, that could increase to 125 million based on industry predictions.
A limiting factor for more people to switch to electric vehicles is range, cost of the battery, as well as recharging time. More important is the number of charging stations and accessibility you can find where you live, which is increasing in developing countries but nonexistent in others. An electric car with a full charge can have a driving range of between 70 to 100 miles. That is quite enough for a day of driving in most cities. Research keeps advancing in trying new battery technologies and chemistries. One example is Sila Nanotechnologies, which is developing a new lithium-ion battery replacing graphite (standard anode today) with silicon improving battery density by 20%.
Lithium-ion batteries will continue being the most used type of battery for the next five to ten years and technology improvements will allow batteries to store energy for longer. However, in the case of renewable energy at least, it will require to explore beyond lithium-ion batteries and other forms of energy storage. It is uncertain how much costs will drop, but the incentives in different countries to reduce carbon emission will continue to propel innovation in energy storage technology.
Xin Luo et al. Overview of current development in electrical energy storage technologies and the application potential in power system operation (2014), Sciencemag.org, Solar Power World, Electrek, The Energy Podcast, The Energy Gang Podcast
Featured image: Solar Power World