The next step in renewable energy? Molten metal batteries

Every day, hundreds of kilowatts of electricity generated by wind turbines goes to waste. They generate too much power that cannot be stored by the limited capacities of existing battery infrastructure. In 2010, however, Donald R. Sadoway, a renowned professor of material chemistry at the Massachusetts Institute of Technology, invented a liquid metal battery that might be able to solve this problem 

In 2011 Sadoway created a startup company named Ambri, and after some recent technological breakthroughs the first commercial battery prototype is finished and is scheduled to be tested in late 2021. The liquid metal battery, or Ambri battery, could revolutionize the battery industry and mitigate the drawbacks of renewable energy in the near future because of its unique design. 

The power grid works in a different way than the gas or water grid. Water and gas can be easily stored in large tanks, but when it comes to electricity, there are no cheap, convenient or efficient methodof large-scale storage. Electricity is generated on demand; the grid can detect when it needs more electricity, and power plants respond to it by generating more electricityWhen too many power plants are feeding electricity into the grid, it signals for them to shut down or de-power.  

Power plants must always meet the power demand; when they do not, a blackout occurs. Blackouts can happen when not enough or too much power is being producedRenewable power plants cannot control when the sun shines, wind blows, or rivers flow, which means they cannot control how much power they generate. This is the largest drawback of renewable energy that the Ambri battery has the potential of fixing.  

In order to guarantee a stable power supply, power grids that have renewable energy power stations must also have conventional power stations that switch on when there is a lack of power. The alternate method of stabilizing the power grid is to store the excess energy being produced and to release it when the supply comes short. If you’d like to learn more about how power grids function, there is a video made by Real Engineering that covers all the bases 

The oldest method of energy storage is called pumped hydro which is simply pumping water uphill into a reservoir. It is very inefficient, and not everyone has millions of gallons of water to pump or the geographical requirements to build a manmade lakeThe best available solution we have right now for large scale energy storage are lithium-ion batteries. However, they have their own advantages and disadvantages. 

“For any application where you’re moving the battery under its own energy, you want a high energy density,” Mr. Robert DuBard, an engineering teacher at RE, said. You don’t want it to weigh a lot for how much energy it’s got.”  

Lithium-ion batteries are why electric cars like Teslas can accelerate to 60 miles per hour in as little as 2.3 seconds. But they are very impractical for storing hundreds of kilowatts at a stationary facility. Not to mention, they have a few safety concerns. 

“Pretty much with any kind of battery, if you discharge them below the minimum voltage it begins to damage the battery itself,” DuBard explained. “With lithium-ion batteries, the danger is that when you get below that minimum voltage, not only does it damage the battery, it also begins to get very hot very quickly and has the potential of igniting.”  

Even so, despite their many disadvantages, lithium batteries are currently the best solution for energy storage, due in part to their low cost. Now mass produced, lithium-ion batteries have gone from a price of $3,000 per kilowatt hour when they were first introduced in the ’90s to only $51.20 per kilowatt hour now 

The Ambri battery is currently more expensive than lithium batteries, but over time, as production technologies improve, the price is projected to drop down to only $17kW/hr

Unlike lithium batteries, the Ambri battery cannot be overcharged or undercharged. It also has a much lower rate of degradation. When a conventional battery is deep cycled (goes from 0% to 100% chargeit degrades over time. Lithium batteries, if deep cycled every day, will lose 20% of their capacity in only 2 years. The Ambri battery can be deep cycled daily for 20 years and lose as little as only 5-10% of its capacity. Deep cycling happens very often in energy facilities since they must regularly charge and discharge their batteries to make up for the fluctuations in the power grid. 

The Ambri battery is also only 80% efficient vs the lithium-ion battery, which is 90efficient but, since it is only a third of the price of the lithium-ion battery, it more than makes up for its lower efficiency. The initial costs will be drastically lower and will make up for the energy that is lost over time. 

The first test of the liquid metal Ambri battery is going to start in late 2021. A company called TerraScale designs, engineers, builds, and operates large scale, sustainable datacenters. They need an energy storage facility for their grid, which is made up of only renewable energy sources. The small-scale grid is the perfect test bench for the Ambri battery. The 250-megawatt battery will be able to power the facility for 12 hours straight. This is only the beginning, as they plan to have a 1 MWh commercial system developed, certified, and in trials by 2022 and production ready 250 MWh batteries ready for customers by 2023. It is possible that liquid metal batteries will revolutionize renewable energy in the near future