In the January issue of Farm Equipment we explored the variety of fuels and technology that will power farm equipment during the mid-21st Century and beyond. Electricity promises to be a major player, particularly as battery technology continues to evolve.
To imagine what electrical technology will power off-road equipment in the coming decades, one needs to pay attention to the automotive industry.
Industry watchers who track the improvement in battery technology speak of step increases and incremental increases, with step increases highlighting new technology rather than improvements on existing designs.
Currently, lithium-ion batteries are undergoing regular incremental improvements which in the past year have allowed Tesla to launch its famed electric “X” roadster with a 220 mile range based on Tesla and Panasonic engineers’ work to further tweak the design of the 30 year-old Li-ion battery.
The technology has advanced to the point where Anheuser-Busch and Pepsi have both announced, with much fanfare, they each will be buying a dozen or so over-the-road Tesla semi-trailer rigs powered with Li-ion technology in the coming year.
Such success points to significant design improvements for the Lithium-based battery for electric vehicles, but even Tesla’s CEO, Elon Musk, says lithium technology — which was a step increase in electrical storage when it was new — is likely near its maximum development for EV use.
In fact, Panasonic engineers, responsible for the Li-ion batteries in Musk’s new X vehicle, say Li-ion batteries can likely be tweaked another 20-30% for range improvement, but freely admit the technology is approaching its theoretical maximums.
Similarly, Toyota, a pioneer in automotive hybrid technology, is currently concentrating its research on solid-state (no liquid electrolyte) and lithium-air batteries.
Toyota says its target is a vehicle with a 500 km range (roughly 300 miles), and that will require batteries that can generate 800-1,000 watt-hours per liter volume — roughly 2-3 times the output of current Li-ion batteries.
Enter the Next Step
When lithium batteries replaced nickle/cadmium and nickle metal hydride batteries, they provided a significant leap in development. Today, lithium may well be looking at retirement with the advent of sodium-based storage cells similar to one recently unveiled by researchers led by Dr. John Goodenough, none other than the inventor of the Lithium-ion battery, himself.
Goodenough, 94, still works at the University of Texas in the Cockrell School of Engineering, where he, Dr. Maria Braga and their associates have developed a solid-state sodium battery with 3 times as much energy density as lithium-ion batteries — a development that could double or triple the range of EVs.
Automotive engineers say when EVs have comparable range to current fossil-fuel vehicles, a tipping point in buyer-thinking and auto sales likely will occur. Goodenough’s new battery might just be what causes the tip.
Goodenough says cost, safety, energy density, rates of charge and discharge and cycle life are all critical for electric cars to be more widely adopted. “We believe our discovery solves many of these problems (inherent in even the most current Li-ion batteries),” he explains.
Upside of Sodium Batteries
The UT sodium battery allows for a greater number of charging and discharging cycles, which equates to longer lasting batteries, plus they can be charged much faster (minutes vs. hours) than current EV batteries, Braga says.
Also, because the new battery uses solid glass instead of a traditional liquid electrolyte found in Lead-acid and Li-ion batteries, it can perform well in subzero-degree weather.
In addition, the new sodium cell is non-combustible, unlike early versions of Li-ion batteries. It likely can be produced at a much lower cost than current Li-ion batteries, say its inventors.
Braga says the glass electrolyte allows alkali metals (lithium, sodium or potassium) to be plated on both the cathode and anode of the battery which sidesteps “dendrite formation” found in many of today’s cutting-edge Li-ion batteries, a condition which tends to short out the cell after frequent recharging.
The sodium batteries developed at the University of Texas have demonstrated they are capable of more than 1,200 charge cycles.
Braga says their experimental cells also enjoy the advantage of being made from “earth friendly” materials. “The glass electrolytes allow us to substitute low cost sodium for lithium, and sodium can be readily extracted from sea water,” she explains. “Lithium comes primarily from strip mines in South America and China.”
