Battery Chemistry and Gravity : Energy Storage Series 2

As the immediacy of the climate crisis becomes ever more apparent, batteries hold the key to transitioning to a renewable-fueled world. Renewables will play a greater role in power generation, but without effective energy storage techniques, it’s an incomplete puzzle.

Chemical engineers have always been fascinated by the periodic table since our introductory days to materials, right from the days of ‘Baghdad battery’ almost 2000 years ago which was made up of ceramic jar, a tube of copper, and an iron rod and a lot of mystery around 'presence of acid' to today’s new age. 

We are looking at all materials available on the earth, which can provide the competitive advantage, chemically and logically, we need to look at cost competitive elements for a more sustainable production and consumption.

This is the Series 2 where we look into companies which could shape future in battery and hydro.

Click here for Series 1 where we had set the introduction to energy storage.

Click here for Series 3 where we look into companies which could shape future in thermal and crystal ball gazing. 😊

There are dozens of chemistry being looked at today. There are hundreds of companies working on scaling up and manufacturing new battery technology. Lithium ion has done remarkable things for technology and much has been talked about it but I would like to focus on other alternatives rather than lithium in this series.

A main alternative being explored is a flow battery, which looks into vanadium redox, polysulfide bromide, and zinc bromide chemistry.

One of the ways of using chemical (vanadium) flow storage technology is to use electrolyte across an ion exchange membrane. The advantages of this type of storage are safety, scalability and long term operations. Vanadium electrolyte used in this battery is non-flammable and allows the battery to operate at room temperature.

British startup RedT Energy produces storage machines that use proprietary redox flow technology to store energy in liquids without degrading. Inflow energy storage electrolyte is stored in tanks, outside of the cell stack making storage solutions scalable, as more electrolytes or stacks can be added on a modular basis. Moreover, these batteries have a long lifespan of over two decades.

Another one for the future is the zinc-iron flow batteries. These batteries are suitable for utility scale wind and solar applications. They are non-explosive, non-flammable, non-toxic, recyclable at the end of their life, and made from globally abundant materials. 

ViZn Energy is deploying a zinc-redox flow battery solution. Its batteries experience zero capacity fade over 20 years and are warranted for up to two cycles per day, giving them significantly more usable output than competitive batteries. The zinc-iron chemistry uses globally abundant materials and is non-flammable, non-toxic, and 100% recyclable at the end of its life.

Unlike lithium ion, flow batteries store liquid electrolyte in external tanks, implying that the energy from the electrolyte and the actual source of power generation are decoupled. The electrolyte is stored within the battery itself. 

Electrolyte chemistries vary, but across the board, these aqueous systems don't pose a fire risk and most don't face the same issues with capacity fade. Once they scale up their manufacturing, these companies say they'll be price competitive with lithium ion.

Primus Power has been working in this space since 2009, and uses a zinc bromide chemistry. It's raised over millions of dollars in funding, including a number of government grants from agencies like the Department of Energy and the California Energy Commission.

Primus's modular EnergyPod provides 25 kilowatts of power, enough to power five to seven homes for five hours during times of peak energy demand and for 12 to 15 hours during off-peak hours. The secret is in simplicity. Primus is able to separate the electrochemical species by taking advantage of the density differences between the zinc bromine and the bromine itself, and the more aqueous portion of that electrolyte.

Another interesting company is ESS Inc, an Oregon-based manufacturer of iron flow batteries, founded in 2011. They're basically batteries in a shipping container and they can provide anywhere from100 kilowatts of power for four hours to 33 kilowatts for 12 hours, using an electrolyte made entirely of iron, salt and water.

ESS is backed by some major players like SoftBank Energy, the Bill Gates-led investor fund, Breakthrough Energy Ventures, and insurance company Munich Re. Its systems, called Energy Warehouses. It's also in the process of developing its Energy Center, which is aimed at utility-scale applications in the 100 MW plus range. That would be 1,000 times more power than a single Energy Warehouse. A lot is to be seen … with hopeful intent.

But for all their potential, flow battery companies like Primus and ESS Inc still aren't really designed to store energy for days or weeks on end.

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Many of those flow battery technologies still suffer from the same fundamental materials cost challenges that make them incapable of getting to tens or hundreds of hours of energy storage capacity. 

Other non-lithium ion endeavors, such as the M.I.T spinoff Ambri, face the same problem with longer-duration storage and Form energy, a battery company with an undisclosed chemistry, is targeting the weeks or months long storage market, but commercialization remains far off.  

Let's look at one of the most basic and ideally one of the oldest ways of stored energy process - Pumped Hydro.

Currently, about 70-80% of the world's energy storage comes from pumped hydro.

When there's excess energy on the grid, it's used to pump water uphill to a high-elevation reservoir. Then when there's energy demand, the water is released, driving a turbine as it flows into a reservoir below. The flaw in the system is that it requires a lot of land, disrupts the environment and the natural working of the geography and can function in specific geographies.

My gut feel says that in the next decade we are going to explore this energy storage process in the places where the geology and the environmental features support it.

Energy Vault, a Swiss gravity-based storage company founded in 2017, was inspired by the concept but thinks it can offer more. Instead of moving water, Energy Vault uses cranes and wires to move heavy (35ton) bricks up and down, depending on energy needs, in a process that's automated with machine vision software. The system tower crane utilizes excess solar or wind to drive motors and generators that lift and stack the bricks in a specific sequence. Then when the power is needed from the grid, that same system will lower the bricks and discharge the electricity.

It can store energy at around half the cost of existing grid-scale storage solutions on a low levelized cost of energy basis, including operations and maintenance costs and parts replacement and can run to 3 to 4 decades with high efficiency and almost zero degradation. This system is sized for utility-scale operation.

A standard installation could include 20 towers, providing a total of 350 megawatt hours of storage capacity, enough to power around 40,000 homes for 24 hours. The trick for this segment will be scale at very large deployments of multiple systems so that they'll have that power on demand for weeks if not months.

It has received funding of $110M from SoftBank Vision Fund, and it's building out a test facility in Milan, Italy in 9months and less than $2 million and a plant for Tata Power for 35MWh.

https://www.ft.com/content/5b06a392-be9b-11e9-89e2-41e555e96722

End of Series 2.

In the next series, let’s look into thermal store energy and some crystal ball gazing into the future.