Energy storage plays an essential role in enabling companies to leverage green energies such as wind and solar. By charging during periods of excess renewable generation and discharging at times of higher demand, companies can maximize their utilization.
Electricity storage comes in many forms. Hydroelectric dams – both conventional and pumped hydro – dominate bulk grid storage solutions currently.
Hydrogen
Hydrogen can be extracted from renewable electricity during periods of lower demand by electrolysis and stored until needed for use in fuel cells to generate power with zero emissions and efficiency.
Hydrogen has the potential to replace batteries in electric vehicles (EVs), but due to energy inefficiencies associated with hydrogen production, storage, and refueling. Researchers are searching for solutions that make hydrogen production and use more practical and cost-efficient.
One option for storing hydrogen underground in salt caverns, depleted oil and gas fields or aquifers has not been tested on a large scale; an alternative approach could use materials which bind hydrogen more securely such as metal hydrides or carbon nanotubes or surfaces, to achieve higher volumetric energy densities than liquid hydrogen; these may also be better suited to long-haul shipping where weight and space restrictions apply.
Batteries
Batteries convert chemical energy to electricity through an electrochemical process, where electrons move back and forth between anode and cathode to generate voltage – this potential electrical charge stored as current by batteries is then released as DC electricity when needed. At PNNL scientists are working hard to develop new materials and improve existing ones to make batteries more cost-effective at grid scale.
These systems can offer the same services provided by dirty peaker plants, helping communities avoid outages and high electricity prices during periods of increased demand. Furthermore, battery storage systems offer load shifting functionality: charging when energy costs less and discharging during peak demand times.
Battery Energy Storage System (BESS) technology adoption is on the rise as businesses seek ways to become energy independent, no longer tied to fluctuations of their local utility grid. BESS systems consist of swappable battery modules with onboard sensors, control components and an inverter.
Flywheels
Flywheels were first utilized as potter’s wheels before expanding their use to large engines and machines during the Industrial Revolution. More recently, flywheels are once again being promoted as eco-friendly alternatives to batteries for power quality applications.
Similar to electrochemical batteries, an electromechanical flywheel energy storage system (FES) consists of a rotating mass with an attached motor/generator that stores electrical energy by converting kinetic into mechanical energy and back again. A FES also requires power conversion system components as well as bearings capable of supporting higher speeds as well as monitoring systems, utility interface equipment and transport features.
Materials with high strength and low density, like composites, are desirable to maximize kinetic energy storage in the rotor. Flywheel systems generally cost the most over their life cycles in terms of capital costs; annual operating costs tend to be determined by capital expenses alone. Schoenung and Hasselzahn (2003) conducted an investigation of three high speed flywheel systems optimized for one second discharges to assess life cycle cost analysis.
Supercapacitors
Supercapacitors provide an efficient energy storage option that optimizes costs, size and efficiency in electronics. Their high power capacities, thermal stability and longer charging cycle life make them superior alternatives to batteries.
Supercapacitors store energy by employing electrostatic methods within their electrode materials. Positive and negative charges are separated via an insulator/dielectric layer sandwiched between their electrode plates to produce static electricity that can be released quickly as needed, unlike batteries which degrade over time and require periodic maintenance to stay efficient.
People have begun using supercapacitors as replacement batteries in consumer devices like laptop computers, mobile phones and digital cameras that require short bursts of power to activate zoom functions. Supercapacitors also enable faster charging of electric vehicles as well as greener, more efficient wind turbines with variable speed capabilities – people even find ways to make them more versatile by selecting various electrode materials like carbon, MXenes MOFs or transition metal-based compounds as electrode materials for these supercapacitors.