Making grid energy storage a reality?

Grid energy storage cannot be scaled with traditional lithium-ion technology.

Some challenges with lithium-ion batteries:

• Thermal runaway due to generated heat.

• High commissioning costs

• Complex maintenance requirements

Ambri’s Liquid Metal Battery technology was founded in 2010 by Donald Sadoway, David Bradwell, and Luis Ortiz with seed money from Bill Gates and the French energy company, Total S.A. It's working towards commercializing grid-scale storage batteries using its technology.

Cost of energy storage

Ambri cells utilize commonly available electrode materials that cost 1/3 of those in NMC lithium-ion cells. The manufacturing of Ambri cells is far simpler and requires 1/3 to 1/2 the capital expense per MWh of production than lithium-ion.

Furthermore, Ambri-based systems do not have cooling, fire suppression, or module- and rack-based BMS equipment as lithium-ion systems require. For these reasons, long-duration Ambri-based battery systems are a fraction of the cost of lithium-ion when comparing 20-year, eight-hour-duration systems.

Pricing claims:

Lithium-ion batteries are projected to drop in price from current levels to less than $100/kWh at some time in the mid to late 2020s. Even compared to this low future lithium-ion price of $100/kWh, these energy storage systems will be significantly more expensive than Ambri-based battery systems.

Ambri and its alternate chemistry technology

The liquid metal battery is comprised of a liquid calcium alloy anode, a molten salt electrolyte, and a cathode comprised of solid particles of antimony, enabling the use of low-cost materials and a low number of steps in the cell assembly process.

How does it work?

The active materials in Ambri’s cells reversibly alloy and de-alloy while charging and discharging. The electrolyte is thermodynamically stable with the electrodes, avoiding unwanted side reactions such as film-formation that can degrade the performance of other cell chemistries. Furthermore, the negative electrode is fully consumed when discharged, and then is reformed on every cycle, resulting in a highly repeatable process with no memory effect.

With these unique operating characteristics, Ambri’s liquid metal battery technology avoids common degradation mechanisms that cause capacity fade in other chemistries.

Temperature response

At room temperature, Ambri’s cell is non-conductive and its active materials are solid metals and a solid electrolyte. Upon heating to 500˚C temperature, Ambri-based battery systems operate at maximum performance level no matter the external temperature and require no power-hungry air conditioning.

Ambri-based systems generate their own heat during use, thereby eliminating the need for auxiliary power for temperature control. These systems like to be used – a full charge/discharge cycle at least every two days will keep the system at its operating temperature and higher duty cycles will not increase degradation

Combustibility and Safety concerns?

To date over 20 lithium-ion energy storage systems have resulted in explosions or fires.

Ambri batteries are not explosive, combustive, or temperature sensitive. No level of overcharging, over-discharging, short-circuiting or temperature has caused any safety concerns with these cells.

Ambri has engaged with Underwriters Laboratories to develop an appropriate set of safety tests for the certification of Ambri cells. Ambri’s cells have demonstrated passing these tests with ease.

Commissioning challenges

On-site installation of pre-fabricated Ambri-based systems is more rapidly deployed than today’s energy storage technologies that require on-site system assembly. This more closely aligns the installation of Ambri’s energy storage systems with the speed of solar installations.

100MW of solar power plus Ambri storage would be installed within six months. Conventional power plants require over five years.

Modular configuration allows scalability to meet the demand for GWh-sized deployments. For GWh-sized deployments, Ambri-based 1-MWh systems are modular and scalable to meet demand.

Ambri’s commercial systems will be packaged in 550 – 1150 VDC containers with up to 1 MWh of capacity. These containers will be factory assembled and shipped to the site fully populated and sealed. Each of these containers will contain no replaceable or serviceable components. This eliminates on-site maintenance and means that the container becomes the modular and replaceable system component.

For projects with 10 or more containers connected in parallel at the DC side of site PCS, system reliability is enhanced through N+1 redundancy at the container level.

Transportation

During transportation, cells are shipped at ambient temperature and are inactive; they have zero cell voltage and are unable to pass current, offering significant safety advantages during assembly and transportation. Once delivered on-site, heaters within the system bring the cells up to their operating temperature, which activates them and allows them to start storing or returning electrical energy.

Although the system is expected to remain at operating temperature continuously for the life of the system, cells are designed to undergo dozens of thermal cycles, from room temperature to 500 °C, without impacting cell performance.

Ambri also claims that these cells are highly tolerant of over-charging or over-discharging and are not subject to thermal runaway, electrolyte decomposition, or electrolyte off-gassing, each of which could lead to significant safety events with other cell chemistries.

Ambri is currently building one of its first battery storage facilities in Aurora, Colorado to demonstrate the efficacy of its technology in partnership with  Xcel Energy. You can learn more about Ambri on their social media. 

What technology/ startup do you think can support grid energy storage? Comment below.