The Power Plant
Liquid Metal Battery Stores Power After Sun Or Wind Retreat

Liquid Metal Battery Stores Power After Sun Or Wind Retreat

Ambri, a Cambridge, Massachusetts startup founded by MIT researchers, is working to turn a new renewable-energy concept into a commercially viable product. Employing Liquid Metal Batteries, their goal is to store power for significantly less than current battery technologies. “If we can Get Liquid-Metal batteries down to $500 a kilowatt-hour, we’ll change the world,”Donald Sadoway, chief scientific adviser at Ambri Inc., said.

This new technology promises an alternative to the massive pumped-water systems that make up 95 percent of U.S. energy-storage capacity. At the lower price, developers will be able to build wind and solar projects that can deliver power to the grid anytime, making renewable energy as reliable as natural gas and coal without the greenhouse-gas emissions.

A major difference between Ambri’s technology and other batteries is its all-liquid design. As shown in the figure, Ambri’s cells are made of three simple components — a salt (electrolyte) which separates two distinct metal layers (electrodes). Cells operate at elevated temperature and, upon melting, these three layers self-segregate and float on top one another due to their different densities and levels of immiscibility. Initially, researchers at MIT worked with magnesium (Mg) and antimony (Sb) electrodes; Ambri is commercializing a chemistry with a higher voltage and lower cost. In a charged state, there is potential energy between the top metal layer and the bottom metal layer which creates a cell voltage. To discharge the battery, the cell voltage drives electrons from the Mg electrode, delivering power to the external load (e.g., light bulb), and the electrons return back into the Sb electrode. Internally, this causes Mg ions to pass through the salt and alloy with Sb, forming a Mg-Sb alloy. To recharge, power from an external source (e.g., wind turbine) pushes electrons in the opposite direction, pulling Mg from the Mg-Sb alloy and re-depositing Mg back onto the top layer, returning the system to three distinct liquid layers. The cell design is simple, uses low-cost materials, and the all liquid design avoids the main failure mechanisms experienced by solid components in other battery technologies.

Another major difference between Ambri’s Liquid Metal Battery and other battery technologies is its capital efficiency in manufacturing. Ambri’s factories will require one fourth to one tenth of the capital investment to produce an equivalent amount of electricity storage per year as other technologies. The active components of Ambri’s cells are housed in steel containers and cell tolerances are in millimeters not microns. Cells are put together in systems using steel racking and other basic components. Consequently, Ambri will be able to leverage workers that have experience building and assembling steel parts, a ubiquitous skill set. This gives rise to its manufacturing strategy of building Ambri’s Liquid Metal Batteries around the world through a network of manufacturers that will serve local and regional markets on a global basis.

image In the world of electricity storage, the Liquid Metal Battery technology performs like both a tractor and a race car. It can respond to regulation signals in milliseconds and can store up to twelve hours of energy and discharge it slowly over time.

Liquid electrodes offer a robust alternative to solid electrodes, avoiding common failure mechanisms of conventional batteries, such as electrode particle cracking. The all-liquid design avoids cycle-to-cycle capacity fade because the electrodes are reconstituted with each charge.

The Liquid Metal Battery operates silently, is emissions-free and has no moving parts.

Ambri’s Liquid Metal Battery technology is unique - it has distinct properties and performance capabilities - and is unlike any other battery technology in the world. As a result, Ambri has secured a strong intellectual property position. The company has filed or has licensing rights to more than 30 domestic and international patents and patent applications and continues to pursue broad coverage.

Supporting the Grid

Today, the electric grid is the largest supply chain in the world with no warehouse. The electricity we use is generated moments before we use it. To keep the lights on, power grids are to meet the highest levels of demand, which occur only a few hours per year. It is hard to get enough electricity into certain areas, like big cities, leading to price spikes and threats of blackouts and brownouts. In addition, no one can control when the sun shines or when the wind blows, making it hard to operate the grid when wind and solar resources are significant contributors. As worldwide consumption is increasing and grid infrastructure is aging, a new solution is required.

The solution is Ambri’s Liquid Metal Battery — a novel grid-scale electricity storage technology. The Liquid Metal Battery will fundamentally change the way power grids are operated on a global basis. It will provide numerous benefits to multiple stakeholders across the electric system value chain:

·     Electric Utilities

·     Independent power producers

·     Transmission operators

·     End-users

The new battery will help integrate renewable resources like wind and solar, creating a cleaner electricity infrastructure; it will offset the need to build additional transmission, generation and distribution assets, which will lower electricity costs; it will enable users to reduce their electricity bills; and it will improve reliability in the face of an aging grid. Ambri’s Liquid Metal Battery will reduce the amount of generation, transmission and distribution infrastructure by enabling the electric grid to be built to meet average demand instead of peak demand.

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