It’s taken 40 years for lithium-ion battery technology to evolve into its current state, powering everything from the smallest electronic devices to Tesla’s 100MW battery farm in southern Australia. But utility-scale Li-ion batteries are rare. 99% of grid storage today is pumped hydro, a solution that will always be limited by geographical and environmental constraints. For utility-scale chemical batteries to take off they need a new technology, says Jim Conca, and that technology is the Vanadium Flow Battery. He explains how the V-flow battery outcompetes Li-ion, and any other solid battery, for utility-scale applications. They’re safer, more scalable, longer-lasting, and there’s much more Vanadium than Lithium in the Earth’s crust. But commercialisation suffers from the high cost of Vanadium extraction. So researchers are working on how to store more electricity through improved chemistry, and improved cell and stack designs. And, of course, lowering the cost of that Vanadium extraction. Conca plots a pathway to making V-flow batteries less than half the cost of Li-ion per kWh.
The efforts to lift our power generation and electrical grid into the 21st century is a multipronged effort. It needs a new generation mix of low-carbon sources that include hydro, renewables and nuclear, ways to capture carbon that don’t cost a zillion dollars, and ways to make the grid smart.
But battery and storage technologies have had a hard time keeping up. And they are critical for any success in a carbon-constrained world that uses intermittent sources like solar and wind, or that worries about resilience in the face of natural disasters and malicious attempts at sabotage.
Research into bigger, better storage
This was pressed home this week by the U.S. Department of Energy’s decision to build a multimillion dollar electric grid research complex at the Pacific Northwest National Laboratory. And better, larger batteries are a main component of this research.
Jud Virden, PNNL Associate Lab Director for energy and environment, noted that it took 40 years to get the current lithium-ion batteries to the current state of technology.
We don’t have 40 years to get to the next level. We need do it in 10.
It’s not like we’ve been idle. We just haven’t been wildly successful. Battery technologies do keep getting better. Recently, Jack Goodenough, the inventor of the Li-ion battery, came out with a new fast-charging battery technology that uses a glass electrode instead of a liquid one, sodium instead of lithium, and may have three times as much energy density as lithium-ion batteries.
And in addition to batteries, we do have other technologies for storing intermittent energy, such as thermal energy storage, which allows cooling to be created at night and stored for use the next day during peak times.
At present, the most widely used storage method is pumped hydro storage, which uses surplus electricity to pump water up to a reservoir behind a dam. Later, when demand for energy is high, the stored water is released through turbines in the dam to generate electricity.
Pumped hydro is used in 99% of grid storage today, but there are geologic and environmental constraints on where pumped hydro can be deployed.
We’ve even looked at other gravity-based energy storage systems, like Advanced Rail Energy Storage, that uses surplus wind and solar energy to move millions of pounds of rock uphill in special electric rail cars that roll back downhill, converting this gravitational potential energy to electricity that goes out onto the grid.
We need utility-scale chemical batteries
But we really need utility-scale chemical battery storage to deal with rapid intermittency in both generation (renewables) and demand (rapid changes in use throughout the commercial day). These need to be very large but very stable and long-lasting.
Lithium ion batteries are what we know now. They can pack a lot of energy storage in a small, light battery, making them the battery of choice in small electronics such as laptops and cell phones.
But Li-ion batteries have too short an operating life and have issues such as rapid heat generation. For the near-future, they will dominate the small-volume niche such as personal devices and electric vehicles, but for the utility-scale commercial battery market, we need bigger systems that last longer.
The latest technology to emerge is the vanadium redox battery, also known as the vanadium-flow battery. And the best one seems to be from WattJoule, especially because their cost is so much lower than other V-flow batteries.
V-flow batteries are fully containerised, nonflammable, compact, reusable over semi-infinite cycles, discharge 100% of the stored energy and do not degrade for more than 20 years. The Earth’s crust has much more vanadium than lithium, and we produce twice as much V as Li each year.
Most batteries use two chemicals that change valence (or charge or redox state) in response to electron flow that converts chemical energy to electrical energy, and vice versa. V-flow batteries use the multiple valence states of just vanadium to store and release charges in a water-based electrolyte containing vanadium salts.
V can exist as several ions of different charges in solution, V(2+,3+,4+,5+), each having different numbers of electrons around the nucleus (see figure above). Fewer electrons gives a higher positive charge. Energy is stored by providing electrons making V(2+,3+), and energy is released by losing electrons to form V(4+,5+).
Flow batteries consist of two tanks of liquid, which simply sit there until needed. When pumped into a chemical reactor, the two solutions flow adjacent to each other past a membrane, and generate a charge by moving electrons back and forth during charging and discharging.
This type of battery can offer almost unlimited energy capacity simply by using larger electrolyte storage tanks. It can be left completely discharged for long periods with no ill effects, making maintenance simpler than other batteries.
Commercialisation of vanadium flow battery systems has suffered from the high cost of the V. So you have to either store more electricity in the same amount of V through improved chemistry, and improved cell and stack designs. Or lower the cost of V.
Making Vanadium extraction cheaper
Said Greg Cipriano, VP Business Development and Co-Founder of WattJoule, “Working with our strategic partners, our proposed integrated, multi-metal extraction approach is the key to lowering vanadium prices. The old conventional way of metal extraction is inefficient and wasteful. Going forward this simply does not make economic or environmental sense.”
Extracting multiple metals from the vanadium rich input source, either fresh ore dug out of the ground or slag, used catalyst or oily fly ash – what are considered industrial waste products – provides additional revenue. The non-vanadium metals, such as iron, titanium, and nickel, are then sold at market prices which subsidises the vanadium extraction.
There is a lot of oily fly ash and coal waste to be had. This subsidy has been found to substantially offset the vanadium cost, and in some cases it can reduce the cost to zero.
Contrast that with today’s sale of vanadium into the highly competitive, cost driven commodity metallurgical market today which is a one-off transaction.
These V-flow batteries can be quite large and best suited to industrial and utility scale applications. They could never fit in an electric car, so the Tesla battery is safe for now. But the V-flow battery outcompetes Li-ion, and any other solid battery, for utility-scale applications. They’re just safer, more scalable, longer-lasting and cheaper – less than half the cost per kWh.
Storing energy for the future is becoming more important as power generation evolves and we need to be more creative, and less costly, than we’ve been so far. We have the tools – batteries, pumped storage, thermal – we just have to deploy them fast.
Hence, the importance of the V-flow batteries.
Dr. James Conca is an earth and environmental scientist and a regular contributor to Forbes magazine