Humans have harnessed renewable energy resources such as wind, running water, solar, or biomass for centuries. Their application has ranged from driving basic mill machinery to heating homes, or fueling various energy demands. Contrary to conventional fuels that can be burnt and used only once, renewables have the ability to be replenished within a very short span of time or are (like wind and solar) never exhausted.
The other significant benefit is their clean energy generation ability. According to 2019 statistics published by the United States Energy Information Administration, the U.S. electricity generation sector accounted for 1.72 billion metric tons of carbon dioxide emissions. That means for each unit of energy produced there was around one pound of toxic emissions generated with it. By comparison, renewables are carbon neutral, which makes them a highly sustainable option for future advancements in the energy sector.
Need For Renewable Energy Storage
A significant factor hindering the wider implementation of some renewable energy sources is the inconsistency of generation. Unlike the predictability of fossil fuels, renewable energy resources vary on a daily basis—such as wind speed, sunlight intensity, etc. This presents a challenge to manage energy generation in such a way that a stabilized supply could be assured. Renewable energy storage options address this shortcoming.
Renewable energy storage (RES) can be described as the mechanism for storing energy generated from renewables during times of maximum production and then supplying it when it is required or allowing backups of this energy supply. Energy storage can play a substantial role in renewable energy integration as it is beneficial for the entire supply chain mainly due to ensuring enhanced electric power quality, dependability, and grid stability. RES decreases power fluctuations by providing reliable, uninterrupted support for sustainable energy buildings and infrastructure that are located even at remote installation sites or other locations dependent on the aging, legacy energy generation grid.
Renewable Energy Storage Techniques
There are many methods of storing renewable energy, permitting excess energy produced during peak hours to be accessed when needed. These include:
Battery Energy Storage Systems (BESS)
Battery energy storage systems utilizing Li-ion or Lithium Iron Phosphate batteries have been a commonly adopted energy storage technique for domestic and microgrid applications where renewables such as solar PV or small-scale wind turbines are involved. During the peak production hours in the day, the energy produced by the PV panels can be utilized to charge the batteries and, in the hours when the sunlight or wind speed drops down—the batteries provide the stored energy to the grid or home. In this way, an uninterrupted supply can be assured. The capacity of these systems can be altered and customized as needs dictate.
Liquid Air Energy Storage Systems
Liquid air energy storage systems work through the utilization of extra-generated energy to drive liquefiers. The liquefiers liquify the available air and store them in the storage tanks. When the energy storage system is needed to supply back this stored energy, the liquified air is allowed to expand. The pressurized air expands to drive turbines coupled with generators to produce energy. According to the reports of Research News, the first energy storage facility of this kind is about to be built in Vermont with a 50MW capacity and eight hours storage capacity totaling400 MWh.
Molten Salt Energy Storage
Molten salts can be heated up easily to high temperatures and heat energy can later be extracted from them. The thermophysical properties of salts such as nitrates of sodium and potassium allow them to be heated to their molten form when energy need is low. When energy extraction is required, their heat is used to power a steam generator. This form of thermal energy storage has found wide applications in Concentrated Solar Power (CSP) and solar PV farms globally. From a study funded by the German Federal Ministry for Economic Affairs and Energy (BMWi) in 2019, it was revealed that molten salt energy storage systems have an electrical storage capacity of 21 GWh including a dispatchable power of 7 GWh from CSP. The average storage time was calculated around 3 to 15 hours for this technology.
Pumped-storage Hydroelectric
These systems consist of two water reservoirs that are located at alternative heights. At the time of excess production, pumps are used to transfer the water to a relatively higher reservoir creating a “potential energy” source. In the hour of need, the water is released down to the lower reservoir, driving the turbines to generate electricity. The statistics from the Energy Information Administration have shown that the installed capacity of pumped hydroelectric storage is around 22.9 GW with California having a highest capacity of 3.9 percent in this affair.
What is in the Future for Renewable Energy Storage?
The future is bright for renewable energy and the storage systems that support them. Researchers are working to further optimize energy storage technologies. Significant advancements have been made in battery technology—such as lowering the costs and improving the efficiency of lithium-ion batteries as well as development of higher energy-density lithium-sulfur batteries. Cost reductions and increased efficiencies in both renewable energy generation and storage will drive expanded adoption of renewable energy systems.
There is a growing array of other emerging energy storage options, including electrolyte liquid-based flow batteries, chilled water thermal energy storage (similar to Molten Salt covered above), flywheels, and ultracapacitors for short duration power. Energy storage needs are site-specific, driven by varying requirements for generation, storage duration, cost efficiency, and many other factors. Designing, financing, sourcing, and delivering the right microgrid for a specific location is a complex process. VECKTA is the leading global marketplace for design, optimization, and procurement of complete Distributed Energy Systems (DES), with a special focus on industrial microgrids.
Contact VECKTA today to learn more about taking control of your energy future.
Photo credits: (RawFilm / Unsplash) (Szabolcs Toth / Unsplash)
