Energy Storage

Hydrogen Energy Storage

Videos from CNBC:

Sustainable Energy YouTube Channel

Why hydrogen is becoming a big deal, CNBC

Why hydrogen is becoming a big deal, part one | Sustainable Energy duration 15:49

Why hydrogen is becoming a big deal, part two | Sustainable Energy duration 10:38

Green hydrogen is gaining traction, but still has massive hurdles to overcome - CNBC - December 2020.

Gravity Energy Storage

Energy Vault

Energy Vault has created the world’s only cost-effective, utility-scale gravity-based energy storage system that is not dependent on land topography or specific geology underground. When energy is needed a tower of 36 ton blocks is disassembled, recovery energy as they are lowered from a tower. When energy is abundant the tower is rebuilt. Advance computer control makes this possible with round-trip efficiencies of 80 to 90%. See

Energy Vault

Gravitricity

The Gravitricity system suspends weights of 500 - 5000 tonnes in a deep shaft by a number of cables, each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed or generated by raising or lowering the weight. Unused mine shafts are candidate sites. See;

Gravitricity Ltd. - a company based in Scotland.

ARES Systems

Advanced Rail Energy Storage (ARES) energy storage technology employs a fleet of electric traction drive shuttle-trains, operating on a closed low-friction automated steel rail network to transport a field of heavy masses between two storage yards at different elevations. The facilities are highly scalable in power and energy ranging from a small installation of 100MW with 200MWh of storage capacity up to large 2-3GW regional energy storage system with 16-24GWh energy storage capacity. See;

Advanced Rail Energy Storage LLC. - based in Washington State

Chemical Energy Storage

Photoelectrosynthesis

Extracting clean fuel from sunlight, Phys.org - Richard Harth, Arizona State University - September 3, 2019

“In new research appearing in the Journal of the American Chemical Society (JACS), the flagship journal of the ACS, lead author Brian Wadsworth, along with colleagues Anna Beiler, Diana Khusnutdinova, Edgar Reyes Cruz, and corresponding author Gary Moore describe technologies that combine light-gathering semiconductors and catalytic materials capable of chemical reactions that produce clean fuel.”

Cryogenic Energy Storage

Liquid Air 'Batteries'

Air turns to liquid when cooled down to -196°C (-320˚F), and can then be stored very efficiently in insulated, low pressure vessels. Exposure to ambient temperatures causes rapid re-gasification and a 700-fold expansion in volume, which is then used to drive a turbine and create electricity without combustion. Such facilities are suitable for large scale storage and can compete with hydrokinetic storage (pumped water).

Highview Power claims round-trip energy efficiencies of up to 70%

Mechanical Energy Storage

Compressed Air Energy Storage

Industrial development of compressed air energy storage (CAES) has made some advances. Since the 1870’s, CAES systems have been deployed to provide effective, on-demand energy for cities and industries. While many smaller applications exist, the first utility-scale CAES system was put in place in the 1970’s with over 290 MW nameplate capacity. Care has to be taken since compressing air heats it up and releasing the pressure cools it down. Thermodynamics have to be managed carefully to the decompress phase doesn't require fuels to heat it up.

Unfortunately, large-scale CAES plants are very energy inefficient. Compressing and decompressing air introduces energy losses, resulting in an electric-to-electric efficiency of only 40-52%, compared to 70-85% for pumped hydropower plants, and 70-90% for chemical batteries. See;

"Ditch the Batteries: Off-Grid Compressed Air Energy Storage" - Low-Tech Magazine - no date.

Flywheel Energy Storage Systems

Flywheel energy storage systems (FESS) use electric energy input which is stored in the form of kinetic energy. Kinetic energy can be described as “energy of motion,” in this case the motion of a spinning mass, called a rotor. The rotor spins in a nearly frictionless enclosure. When short-term backup power is required because utility power fluctuates or is lost, the inertia allows the rotor to continue spinning and the resulting kinetic energy is converted to electricity. See;

"Turn Up the Juice: New Flywheel Raises Hopes for Energy Storage Breakthrough" - Scientific American - Chris Nelder - April 10, 2013

Aluminum-air Flow Batteries

Researchers at the School of Energy and Chemical Engineering at Ulsan National Institute of Science and Technology claim to have developed a new type of aluminum-air flow battery for EVs. The new battery outperforms existing lithium-ion batteries in terms of higher energy density, lower cost, longer cycle life, and higher safety. Aluminum-air flow batteries are primary cells, which means they cannot be recharged via conventional means.

"A novel catalyst for high-energy aluminum-air flow batteries" - Phys.org - Ulsan National Institute of Science and Technology - Oct 15, 2018

Conventional Battery Technology

Conventional battery technology includes a number of chemistries.

• Lithium-Ion
• Lithium-Ion Polymer
• Nickel-Cadmium
• Lead-acid
• Silver Oxide
• Alkaline

From IDTechX, a report on the future of battery technologies is available for purchase (from $5,750):

"Solid-State and Polymer Batteries 2019-2029: Technology, Patents, Forecasts" - undated

"This report covers the solid-state electrolyte industry by giving a 10-year forecast till 2029 in terms of numbers of devices sold, capacity production and market size, predicted to reach over $25B. A special focus is made on winning chemistries, with a full analysis of the 8 inorganic solid electrolytes and of organic polymer electrolytes. This is complemented with a unique IP landscape analysis that identifies what chemistry the main companies are working on, and how R&D in that space has evolved during the last 5 years."

Energy Density of Different Storage Technologies

The higher the energy density of a fuel or storage technology, the more energy may be stored or transported for the same amount of volume. The energy density of a fuel or storage technology per unit mass is called the specific energy of that fuel or storage technology.

The higher the numbers for renewable technologies the easier it becomes to replace fossil fuels in transportation, for example Gasoline has a specific energy of 12,888.9 Watt-hours/kg, while Lithium-Ion batteries are 100.00–243.06 Watt-hours/kg. However, available energy has to be considered. Internal combustion engines have a 20-40% efficiency, while the efficiency of batteries/electric motors are expected to be higher, and depends on other features like braking energy recapture.