Inventor Ray Kurzweil is known for developing the text-to-speech reading machine and one of the first musical synthesizers. He is also a futurist, responsible for the “Law of Accelerating Returns,” which says the rate of change in most technology increases exponentially.
His theory was built on Moore’s Law, which states that the total amount of transistors that can be embedded into integrated circuits doubles every two years. While this holds true for the semiconductor and photovoltaic, there is one laggard in the mix—one that underpins modernity and is crucial to renewable energy. That slacker is the battery.
The first scientifically described battery was created in 1799 by Alessandro Volta using zinc and copper plates with a saltwater-brine electrolyte. The lead-acid battery used in most automobiles was developed in 1859. Its longevity can be attributed to its low cost of production and high specific power or discharge rate.
It wasn’t until 1957 that a patent was granted for the disposable alkaline battery. The lithium-ion technology that powers everything from smartphones to airplanes was initially described in the 1970s, but wasn’t fully commercialized until the early ’90s.
In the 130 years since the introduction of the lead-acid combo, energy density (i.e., the amount of available power) has increased five-fold. While 500 percent seems like a lot, it is not the kind of exponential growth described by Kurzweil or Moore.
Why are advancements in battery technology important to green energy? The amount of solar energy falling on Earth each day is many orders of magnitude greater than what is consumed on an annual basis. But there are several roadblocks to converting this daily gift into electricity beyond the construction of solar/wind farms.
What happens when the sun don’t shine and the wind don’t blow? The ability to provide extra power during periods of peak consumption also raises issues. Without a method to store excess production for later use, fossil fuels will remain a core component of electricity.
Currently, lithium-ion technology provides the biggest bang for the buck, due to its comparatively high energy density, which has doubled over the last 30 years. Improvements in manufacturing have seen prices fall dramatically over that same period. But lithium does have drawbacks. There is only a finite amount, and it has to be mined. Experts estimate total global reserves are somewhere between 3.5 and 40 million metric tons.
Copper ore, which has been mined for millennia, still holds reserves more than ten times lithium’s highest figure. It’s also highly reactive in the presence of oxygen and can explode from defects in manufacturing.
The perfect storage device would be made of low-cost, commonly sourced materials, have high energy density and output, zero toxicity, and resolve long-standing issues with liquid electrolyte use. One technique is replacing the liquid electrolyte with a solid-state medium. Solid lithium, sodium, and magnesium compounds with high ion mobility are currently being put through their research paces.
The inventor of the lithium-ion battery, John Goodenough, is working with the University of Texas to develop a lithium-glass electrolyte with reworked electrodes. The result is a battery that has three times the energy density and a longer lifespan. Substituting sodium for lithium should be a smooth transition: Sodium—one of the elements in salt and seawater—hardly requires much environmental disturbance to obtain.
Still, solid-state batteries do not lend themselves to delivering immediate power to the grid during peak consumption. A Superconducting Magnetic Energy Storage (SMES) device would be a perfect fit were it not for the cost of the components and having to cool them. The power stored in this type of battery can be discharged into the grid almost instantly. Aside from their high power output, they also provide a low self-discharge rate due to the absence of electrical resistance and zero moving parts.
Researchers at the Heidelberg University Center for Quantum Dynamics have discovered that when confined to a two-dimensional plane, electrons tend to pair up and exhibit superconducting properties. Current high-temperature superconductors are known to have a layered structure, but its importance was not recognized until now.
This same team also noticed that electron pairing occurred at temperatures much higher than the critical point. Extrapolating into the future, one could imagine a layered solid-state high temp superconducting battery with an energy density comparable to fossil fuels like gasoline.