Feature Report: Electricity Storage

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Making Electricity Storage Accessible to Consumers

While we have known for some time how to store electricity on a large scale - with dams, for example - and on a small scale with batteries in cars and electric vehicles, phones and computers, storing electricity for an entire home or a neighborhood is still a challenge. New technologies should help to expand home storage by consumers and to promote the development of electricity generated from renewable sources

Batteries are essential for storing electricity in everything from factories to electric vehicles, electronic devices and, tomorrow, homes. ©Thinkstock

Batteries Have Made Storage Accessible to Everyone

Batteries are one of the primary electricityForm of energy resulting from the movement of charged particles (electrons) through a conductor... storage solutions available to consumers. With batteries, electrical energy is converted into chemical energy, which is the most suitable form for individual users. The concept is based on a reversible chemical reaction. When a battery charges, the flow of electrons, which are negatively charged, moves in one direction, resulting in a stream of positive ions. As a battery loses its charge, both the electrons and ions move in the opposite direction.

Mobile devices such as cell phones, laptops and electric vehicles run on batteries for several hours without recharging. Electricity storage must therefore meet significant technical constraints in terms of compact size, rapid charge/discharge cycles, useful life, etc. Most of today’s mobile devices are powered by lithium-ion technologyTechnology in which energy is stored in batteries containing lithium-ion electrolyte.... Lithium-ion batteries store energy thanks to the movement of lithium ions from one side of the battery to the other. Their drawbacks include high cost, the foreseeable scarcity of lithium in the more or less near future, and capacity fade over time. This technology is increasingly used for mobile applications due to its high energy densityThe amount of energy stored in an object, expressed in watt-hours per kilogram (1 Wh/kg = 3.6 kJ/kg).... However, the cost factor makes it unsuitable for stationary applications.

The batteries used by Bluecar, which were developed by Bolloré for the Autolib' car-sharing service in Paris, represent a notable exception to the dominance of lithium-ion batteries. The service’s electric vehicles feature a unique technology known as LMP (for Lithium Metal Polymer). The battery's maker claims that it is completely safe for the environment as it is made from non-polluting materials. At the end of the battery's life, all of its components can be recycled1. Since Bluecars are hooked up to charging stations whenever they are not in use, they store energy virtually non-stop thanks to their LMP battery, which has an announced service life of 400,000 km.

Stationary electricity storage for homes and neighborhoods has emerged as a promising market.

Stationary Applications

The competition among battery technologies for mobile devices points to the development of a new market for stationary storage applications. These differ significantly from mobile applications in that weight is not an important factor since portability is not a concern. On the other hand, it is essential to limit as much as possible the cost of investment for stationary storage technologies, which increases the cost of the electricity delivered to end customers.

The development of stationary applications is deeply interconnected with the development of photovoltaics and wind powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output..., and in particular electricity generation by consumers using renewable energyEnergy sources that are naturally replenished so quickly that they can be considered inexhaustible on a human time scale... from wind turbines, solar panels, etc. These types of energy have a major drawback, however, which is their intermittent availability. Electricity generation is directly dependent on the current availability of a given energy source (wind, sun or water), which may not always coincide with demand. Implementing stationary storage applications will remove the constraints related to intermittent supply and promote the use of photovoltaics and wind turbines to generate electricity for both single-family homes and entire neighborhoods.

Thinking Ahead

Energy storage may not be cost effective at the moment, but this could change very soon. The growing proportion of intermittent renewable energy sources in the overall energy mixThe range of energy sources of a region. creates a risk of instability for both the French and European power grids. Such disruptions hold back the development of solar and wind electricity. Individual energy storage offers a potential solution, as it helps to regulate and stabilize the injectionSecondary oil recovery method in which water or gas is injected into a deposit to increase pressure in the reservoir... of electricity from renewable sources into the power grid, while also giving people a certain level of energy independenceThe ability of a country or region to meet all its energy needs without having to import primary or final energy. . These advantages also explain why this promising solution is now being promoted by green energyPrimary energy is described as "green" or "clean" when only small amounts of pollutants are generated during its conversion... trailblazers like Germany and the United States.

 
 

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(1) Source Bluecar