System upgrade - The world of tomorrow [Energy storage]
Energy storage is the capture of energy produced at one time for use at a later time. A device that stores energy is sometimes called an accumulator. Energy comes in multiple forms including radiation, chemical, gravitational potential, electrical potential, electricity, elevated temperature, latent heat and kinetic.
Because of the popularity of electrical devices and sources and the global electrical grid network, this article is about electricity storage.
Many type of electrical storage technologies are avaible, the most popular technologies avaible are batteries and fuel cells.
The best technology depend on the need, we can separate the need in three categories:
- Low powering rate [0 - 1kWh] (smartphone, laptop, etc...)
- Medium powering rate [1 - 100kWh] (bicycle, motorcycle, car, etc...)
- High powering rate [100kWh - 1gWh] (power backup for building, network load regulation)
A laptop battery is around 66Wh, a full electrical car battery is around 84kWh, a 1 day power backup for a medium home is around 42kWh.
To regulate network load, huge electrical storage capacity is needed, we need to talk about mWh and even gWh. By example, at midday, the power bid is huge and electricity sources offer a quite stable or unregular production, it's often pumped hydro power storage that stabibilize the power provided to suit the bid and give everyone the possiblity to cook.
Plenty of technologies are avaible, but only a few suit the actual need and are competitive.
Lithium-ion battery
Lithium-ion batteries are common in home electronics. They are one of the most popular types of rechargeable batteries for portable electronics, with a high energy density, tiny memory effect and low self-discharge. Beyond consumer electronics, LIBs are also growing in popularity for military, battery electric vehicle and aerospace applications.
- Specific energy: 0.36–0.875 MJ/kg
- Energy density: 0.90–2.43 MJ/L
- Charge/discharge efficiency: 80–90%
- consumer price: $300–500/kwh
- Self-discharge rate: 8% at 21 °C, 15% at 40 °C, 31% at 60 °C per month
- Cycle durability: 400–1200
Suit for: Low powering rate - Medium powering rate.
Lithium-ion batteries have a great energy density and charge/discharge efficiency, however the discharge rate and cycle durability make them weak and still costly and the technology is at it's near peak of efficiency.
Lithium-ion batteries can pose unique safety hazards since they contain a flammable electrolyte and may be kept pressurized. An expert notes "If a battery cell is charged too quickly, it can cause a short circuit, leading to explosions and fires".
Lithium-ion batteries require cobalt that can pose some serious humanitarian and environment issues.
Solid-state battery chemistry with glass electrolyte
A team of engineers led by 94-year-old John Goodenough, professor in the Cockrell School of Engineering at The University of Texas at Austin and co-inventor of the lithium-ion battery, has developed the first all-solid-state battery cells that could lead to safer, faster-charging, longer-lasting rechargeable batteries for handheld mobile devices, electric cars and stationary energy storage, the battery is still in development but has already be tested.
The researchers demonstrated that their new battery cells have at least three times as much energy density as today’s lithium-ion batteries. A battery cell’s energy density gives an electric vehicle its driving range, so a higher energy density means that a car can drive more miles between charges. The UT Austin battery formulation also allows for a greater number of charging and discharging cycles, which equates to longer-lasting batteries, as well as a faster rate of recharge (minutes rather than hours).
- Specific energy: ? But higher than LIBs
- Energy density: ~ 2.7–7.29 MJ/L
- Charge/discharge efficiency: ? But higher than LIBs
- consumer price: ? But lower than LIBs
- Self-discharge rate: ? But lower than LIBs
- Cycle durability: 1200+
Suit for: Low powering rate - Medium powering rate.
This new battery will replace Lithium-ion battery, but some tests and manifacturing process improvment must be done before commercialization.
Hydrogen fuel cell
Fuel cells work like batteries, but they do not run down or need recharging. They produce electricity and heat as long as fuel is supplied. For hydrogen fuel cell, the fuel supplied is generally contained into high-pressure tanks.
The module that transform the hydrogen into electricity using chemical transformation is called a Polymer Electrolyte Membrane or Proton Exchange Membrane, often cited as PEM or PEMFC for Proton Exchange Membrane Fuel Cells.
The transformation use hydrogen and oxygen and produce heat and water.
- Specific energy: Depend the hydrogen storage medthod and size
- Energy density: Depend the hydrogen storage medthod and size
- Charge/discharge efficiency: 50-70%
- consumer price: Lower than LIBs for medium powering rate, higher than LIBs for low powering rate.
- Self-discharge rate: 0
- Cycle durability: ∞
Suit for: Low powering rate - High powering rate.
Specific energy and energy density are in general higher for medium powering rate. While the charge/discharge efficiency is lower than lithium-ion batteries, the technology is still very young and the efficiency can go up to 83%.
Recharging is an hydrogen fuel cell is instantanous as long as the hydrogen is already produced. Hydrogen production time depend on the electrolysis module size.
source 1, source 2, source 3, source 4
Pumped hydro power storage
Pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost surplus off-peak electric power is typically used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power.
This technique is currently the most cost-effective means of storing large amounts of electrical energy, but capital costs and the presence of appropriate geography are critical decision factors in selecting pumped-storage plant sites.
- Specific energy: ?
- Energy density: ?
- Charge/discharge efficiency: 70-80%
- consumer price: Lowest cost for high powering rate.
- Self-discharge rate: 0
- Cycle durability: ∞
Suit for: High powering rate.
The main disadvantage of PHES is the specialist nature of the site required, needing both geographical height and water availability. This technique is currently the most cost-effective means of storing large amounts of electrical energy, but capital costs and the presence of appropriate geography are critical decision factors in selecting pumped-storage plant sites.
Cool stuff!
Thanks ^^