The Pearl Street Station, invented by Thomas Edison in 1882, is the first steam powered electrical distribution plant, and because of competition between him and George Westinghouse, the technology increased rapidly in the following years. By 194o middle class homes had a lot of the conveniences we have today, like refrigerators, air conditioning and telephones. Today, as the demand for renewable energy increases, we have to develop a new way store all of it, revolutionizing the use of batteries.
The Lithium Ion Revolution
In The Powerhouse, author Steve Levine explains how when John Goodenough first discovered the principles of lithium-ion batteries in 1979, it was little more than an academic curiosity and hardly anyone took notice. By the early 1990’s though, improved microchips created demand for more powerful portable devices and Sony developed a commercial version.
Since then, as researchers from the Joint Center for Energy Storage Research (JCESR) point out in a paper explaining the issues surrounding energy storage, Lithium ion technology has continuously improved over the past 25 years. This has lead energy densities to improve on earlier technologies by a factor of six and costs to drop by a factor of 10.
In a conversation, George Crabtree, Director of JCESR, explained what the ramifications of these improvements have been. “Batteries take up 90% of the weight and volume of a laptop,” he told me. “So imagine what they would look like if they were 6 times bigger.” Wireless technology, as we know it, simply wouldn’t be possible.
Yet today, Lithium ion batteries are doing far more than simply power laptops and smartphones, but are being used in high performance cars like the Tesla Model S and the Chevy Bolt. They are also being deployed to overcome the intermittency of renewable energy sources like solar and wind and to replace inefficient peaker plants that run only in times of high demand.
Still, while there has been enormous progress, Lithium ion batteries are still too expensive to displace conventional technologies such as gasoline engines for cars and gas turbines for electricity. Prices need to fall by an additional 50%-80% to be economically compelling for cars and the grid.
Theoretical Limits Approaching
In some ways, Lithium is a perfect material for batteries. The lightest metal on the periodic table, it is able to achieve high energy densities by insinuating itself into other materials through a process called intercalation. So to create a battery, you store the Lithium ions in an anode, which discharge through an electrolyte to a cathode on the other side of a circuit. To charge back up, you simply reverse the process.
Over the past 25 years, we’ve been able to improve battery performance by modifying or replacing materials to create batteries that operate more efficiently and degrade more slowly. But the dominant factor has been cost, which has fallen by a factor of ten since lithium-ion batteries were introduced.
These two factors, increased performance and dramatically lower cost, are what’s gotten us to the point where electric cars can go 200 miles on a single charge and Lithium ion grid storage has become competitive for some applications. What’s more, efficiencies continue to improve, often faster than most observers had predicted.
However, there are some difficulties. First, the process of intercalation causes the battery’s components to degrade as it charges and discharges. Second, due to its basic chemistry, there is only so much Lithium you get to fit in between carbon atoms in the anode and cathode, so there is an upper limit to how much energy density you can achieve.
So now, battery technology, much like Moore’s law in information technology, is approaching its theoretical maximum performance. Crabtree predicts that it we might be able to get 50% to 100% better performance, but certainly no more than that. To create a true energy transformation, we will have to create new and different technological strategies.
Going Beyond Lithium
With the theoretical limits of Lithium ion batteries approaching, researchers are hard at work pursuing three basic strategies. The first is to simply replace Lithium with another metal, such Magnesium, Calcium or Zinc. These are much cheaper materials and may have dramatically higher energy density potential than the present technology.
Another strategy is to replace intercalation with a chemical reaction that can store and then release energy, such as when Lithium and Sulfur combine to form Li2S. Crabtree believes that Lithium Sulfur batteries may be able to increase the energy density potential by a factor of five using far cheaper materials.
The final strategy is to use liquid flow batteries. These tend to be much heavier and larger, so are less suitable for car batteries, but have tremendous potential to provide utility-scale grid storage that can help make renewable energy both practical and affordable. While they may not improve energy density, early indications are that flow batteries can lower costs enormously.
All of these strategies are being aggressively pursued. The JCESR already has developed working test cells and is looking to develop viable prototypes in the next few years. Several grid storage startups, such as Fluidic, Energy Storage Solutions and Primus Power are already offering solutions for the commercial market or have them in development.
The truth is that nobody really knows what the answer to the energy storage problem will be, but it’s become one of the hottest areas for research investment, both public and private.
Innovating The Innovation Process
It’s been over 150 years since Alessandro Volta built the first battery, so any significant improvement will test the bounds of human knowledge. As Eric Rohlfing, a Deputy Director at ARPA-e told me, “Folks like Tesla and others are pushing the boundaries, but we know there are limits to Lithium ion.” Sowe need to think differently about innovation to create a serious impact.
One new strategy is Rohlfing’s agency itself, which he says “supports ideas in the high risk, high return ideas in the concept stage and push them to where they can attract further funding.” So far, it’s been an enormous success,attracting $1.25 billion in private follow-on funding, nearly five times the agency’s annual budget of about $280 million.
Another novel approach is Crabtree’s JCESR, which combines the efforts of researchers from government labs, academic research institutions as well as private companies. It aims to not only accelerate the discovery of new batteries, but their commercialization as well. “Our aim is to create something transformative, not merely competitive,” he says. And so, we might very well be at a similar point that we were in 1882, when Thomas Edison opened his first power station. It’s doubtful that anyone could have predicted what it would lead to, but it touched off nearly a century of unprecedented productivity growth. With a little luck, history might repeat itself.\