Energy storage provides multiple advantages to electricity grids. Energy storage technologies include rechargeable lead-acid and lithium-ion batteries, flywheels (which store kinetic energy), pumped hydro storage systems such as Llyn Stwlan dam in Wales and more.
Many of these systems are integrated with solar photovoltaic projects or built into urban areas as resiliency hubs, providing another option to replace fossil fuel peaker plants that only operate during select times of the year and can have adverse health impacts in overburdened communities.
Electricity
Electricity storage offers multiple energy services, from frequency response, reserve capacity and black-start capability, to smoothing electricity consumption for end-user demand charges (peak shaving) or even reducing them altogether. Electricity storage may be deployed at various segments of the grid – transmission networks, distribution networks or behind the meter. Fast response ESSs like lead-acid or lithium-ion batteries provide fast response ancillary services at second-by-second intervals while improving power quality by reducing momentary spikes, surges and sags from happening across the grid.
ESSs can be deployed at the distribution network level to support distributed renewable generation and reduce end-user demand charges, or be combined with solar or wind power plants to bridge any output gaps that arise between their variable output and electricity demands. They may also be integrated with microgrids for greater resilience or used residentially to decrease reliance on fossil fuel peaker plants (known as “dirty peakers”).
Heating and Cooling
Energy storage uses thermal systems to collect cold or heat at one point for use later, such as an ice storage air conditioning system using off-peak electricity to freeze water in large vessels and reduce compressor use during peak demand for cooling. More advanced energy storage techniques include solar thermal electric power plants that use molten salt storage to store solar heat before producing electricity when required.
Fossil fuels such as coal and gasoline serve as energy stores by storing ancient solar radiation chemically. Other long-standing technologies for energy storage include pumped hydro storage – using water reservoirs to store gravitational potential energy; rechargeable batteries; and flywheels which make use of inertia – among others.
Compressed air energy storage, another recent innovation, converts surplus electricity to hot, pressurized air using excess energy stored underground chambers before running it through a turbine linked to an electric generator and running it through an electric turbine generator. Compressed air can later be reheated as necessary in order to produce additional electricity when required.
Transportation
Energy storage comes in many forms. While much of today’s storage capacity comes in the form of pumped hydro and batteries, other technologies also play a vital role.
Rechargeable batteries like lead-acid, lithium ion and nickel-metal hydride batteries store chemical energy that can quickly be converted to electricity. Other technologies, including sodium-sulfur metal air flow batteries are rapidly improving cost and lifespan while supercapacitors provide higher power density with faster charging and discharging times than rechargeables alone.
At utility scale, energy storage systems (ESS) can help augment intermittent solar and wind power plants by providing dispatchable capacity when most needed–like during evening peak demand. On a smaller scale, behind-the-meter battery storage can help households reduce electricity demand on the grid while commercial/industrial-grade versions may even replace natural gas or fossil fuel peaker plants altogether.
Community Resilience
Community resilience is an emerging concept that is receiving increasing consideration by disaster planners and government agencies. Going beyond disaster preparedness, community resilience seeks to address the many systems which contribute to community health and wellbeing.
An example of a resilient community would include having an established local job economy and stable money flows within it, residents with strong pride for the community supporting each other and an ability to cope with natural disasters or environmental stresses.
But community resilience can be hard to define; research shows 57 distinct definitions (see online supplementary table). At the National Institute of Standards and Technology, research into community resilience aims at understanding integrated performance of physical infrastructure systems as they relate to social and economic systems as well as developing methodologies for assessing it based on time to recover function or other metrics.