Aurelia Butler

Ambitious goals are often called moonshots, but the challenge of addressing climate change will be even more monumental. This “Earthshot,” as MIT President L. Rafael Reif calls it in an op-ed published today in The Boston Globe, is an enormously complex problem with no single right answer, no clear finish line, multiple stakeholders with conflicting priorities, and no central authority empowered to solve it.

The “super wicked problem” of bringing the global economy to net-zero carbon and adapting to aspects of climate change we can’t prevent will require sustained contributions from every corner of industry, government, academia, philanthropy, and every individual, Reif writes.

To get there, he argues for pursuing two tracks at once. “On path one, we must go as far as we can, as fast as we can, with the tools we have now. And by tools, I mean not only science and technology, but also policy, infrastructure, behavioral and cultural changes, and more,” he writes.

“But the fact is,” he adds, “current technology alone will not get us to the 2050 target.”

Reif thus proposes a path two, involving the creation and deployment of new tools, including science and technology breakthroughs, to approach the many parts of the climate change problem, including aviation, supply chains, agriculture, environmental justice, jobs, and much more.

To meet this path two challenge, he writes, research universities have a special role: “to spawn ideas that meet the needs of different sectors, and to optimize a system for speeding the mind-to-lab-to-market flow of technological answers, while helping to shape policies and processes to support adoption at scale.”

For instance, MIT has launched the MIT Climate Grand Challenges, which has led to novel proposals, from capturing carbon dioxide by domesticating fast-growing microbes to developing plasma-assisted technologies as enablers of green aviation.

Universities can help “tough tech” ideas like these reach the market by creating specialized accelerators. In the MIT ecosystem, The Engine identifies entrepreneurs with bold new-science answers to deep societal problems and connects them with impact investors.

The Institute is also working to create an innovation marketplace based on collaboration, not competition. For example, the member companies of the new MIT Climate and Sustainability Consortium are working with MIT researchers and with each other to speed the creation, testing, and deployment of practical climate solutions within their production processes, supply chains, and service models.

“With a super wicked problem, nobody has all the answers. But if individuals and institutions in every part of the economy and society tackle the pieces of the problem within their reach and collaborate with each other, we have a real shot — an Earthshot ­— at preserving a habitable world,” Reif writes. More

Kiara Wahnschafft started her first company at age 16. After her classmate passed away from a drunk driving accident, Wahnschafft couldn’t stop thinking about ways technology could have saved a life. With two other students, she built a prototype for a car key that works only after the driver passes a breathalyzer test. Wahnschafft went on to create a company called SafeStart Technologies, ultimately patenting the product and winning several competitions.

The experience was Wahnschafft’s introduction to a unique way in which she could improve the lives of those around her. “I was always looking for an artistic outlet as a kid,” she says. “When I discovered programming, it was like I finally had this blank canvas on which to freely create potentially meaningful solutions.”

Wahnschafft arrived at MIT with the desire to continue pursuing product engineering for social entrepreneurship. She experimented with mechanical engineering classes through MIT D-Lab, a program focused on equitable design and development, and soon found herself surrounded by startups working to alleviate poverty and improve living standards around the world. One company, called Sanergy, stood out to her for its innovative approach toward improving sanitation in urban settlements. Through a PKG Center fellowship, she traveled to Nairobi, Kenya, and interned at Sanergy during Independent Activities Period (IAP) in January, 2020.

On her first day, Wahnschafft went with co-workers to the settlements where the company’s sanitation units were being built. Seeing the systems and meeting those operating them in person, as well as speaking with new co-workers and friends who had grown up in Nairobi, gave her a much deeper understanding of the challenge. While her engineering work focused on improving sanitation conditions, she learned more about the systemic reasons why settlements were expansive in the first place.

One of these such issues was job instability. Upon returning to MIT, Wahnschafft dove into an economics research opportunity focused on evaluating a program that teaches Kenyan workers skills needed for digital work. The findings revealed that the program helped to improve wages, employment, and life satisfaction. Wahnschafft then shared her findings with the program’s managers, providing them quantitative reasons to expand their work. The experience introduced her to an evidence-based method for tackling societal challenges.

Today, Wahnschafft is a junior studying both mechanical engineering and economics. In her career, she aims to help solve what she deems the greatest global challenge of our time: the climate crisis. In learning about and working on the energy transition, Wahnschafft often finds herself leveraging her two disciplines together. For example, she notes, “if we’re proposing the installation of heat pumps, it’s helpful to understand both the technical justification for their energy efficiency and the economic policies required for their widescale adoption.”

As a researcher in the MIT Environmental Solutions Initiative Rapid Response Group and the MIT Sloan Climate Pathways Project, Wahnschafft has written multiple briefs to inform Massachusetts and federal policymakers, often utilizing MIT climate research to do so. Both now and in the future, her goal is to ensure climate policy is backed by scientific evidence.

Wahnschafft has also collaborated with the student body and leaders in the administration to improve MIT. As the chief of staff of the Undergraduate Association (UA), the undergraduate student government, she has focused on pulling the student voice into Institute decisions in this unique year, particularly in the area of climate change. She worked with a large group of students, interviewing faculty and other stakeholders in the process, to develop recommendations for climate action at MIT, and is now working with the Institute’s administration to incorporate some of these ideas into MIT’s Plan for Action on Climate Change.

At a forum about MIT’s Climate Action Plan, Wahnschafft spoke on a panel focused on MIT’s role in the energy transition, and proposed ideas on ways to coordinate the wealth of climate research on campus. After working for a few different MIT climate-focused research centers, she has seen how “MIT has all this amazing research, but it’s often in silos.” After conversations with many faculty and students, she believes that MIT can “exponentially increase its impact” by connecting researchers with each other and with opportunities to influence climate policy.

Effective communication is also the theme of Wahnschafft’s favorite class, 11.011 (The Art and Science of Negotiation), for which she has served as a teaching assistant. She believes that the course should be an essential part of any MIT student’s curriculum. “I used to think negotiating meant sitting down at the bargaining table to haggle over prices,” she says. “Through the class, you learn that negotiation is so much more: It is practicing empathy and finding common ground. Especially in our polarized country, and especially on issues like climate that are so cross-cutting, we need to open up conversations to reach some mutual understanding.”

Wahnschafft plans on putting her negotiation skills to the test this summer, when she will be interning in Washington through the MIT Washington Summer Internship Program. She hopes to continue working on climate issues that sit at the intersection of evidence and policy. She feels “It’s going to take time to solve the climate crisis. But my everyday focus will be thinking about if the decisions I’m making are always socially and ethically responsible,” says Wahnschafft.

“I think that as MIT students, we need to be very thoughtful with where we choose to dedicate our minds. I know so many of my peers will go on to become incredible leaders in all types of important organizations,” she says. “We so often have such incredible opportunities at our fingertips during and after our time at MIT, and that’s amazing. So, we can and should be intentional with which of these we pursue and in the decisions we make as leaders, always considering the implications for our diverse local and global communities.”

Wahnschafft applies the same principles when looking the the future. “I’ve had the most incredible education and am very often thinking about where I can best apply it to make this world a little better. Applying my education to help combat climate change, one of the greatest global challenges in history, is the way in which I hope to make a difference.” More

Found in jewelry, car parts, pigments, and industrial chemical reactions, the metal chromium and its compounds are often employed for their color, finish, and anti-corrosive and catalytic properties. Currently, geoscientists and paleoceanographers from MIT and the Woods Hole Oceanographic Institution (WHOI) are looking to add another use to that list: as a way to examine chemical shifts in ancient Earth’s oceans and atmosphere that are preserved in the seafloor’s paleorecord. More specifically, they want to reconstruct rising atmospheric oxygen levels, which began around 2.4 billion years ago, and their effect on the seas. Since biology and the environment are intimately intertwined, this information could help illuminate how the Earth’s life and climate evolved.

While researchers have widely applied chromium as a tool to understand the rock record around this global transition, they’re still working out what different chemical signals mean. This is especially true for evaluating ocean sediments, which could reveal where and when oxygen began penetrating and was being formed in the oceans. However, paleoscientists have largely lacked an understanding of how trace amounts of chromium mechanistically interact and cycle in modern, oxygenated seas, let alone the early oceans — a key component needed for any interpretation — until now.

Research recently published in the Proceedings of the National Academy of Sciences and led by MIT-Woods Hole Oceanographic Institution Joint Program graduate student Tianyi Huang investigated the trace metal’s promise as a paleoproxy for oxygen. For this, the team tracked how oxygen-sensitive chromium isotopes circulated and how they were chemically oxidized or reduced within an oxygen-deficient patch of water in the tropical Pacific Ocean, an analog for early, anaerobic seas. Their findings help validate chromium tracking as a reliable instrument in geology toolbox.

“People have seen the that chromium isotopes in the geological records kind of track the atmospheric oxygen levels. But, because you’re using something that is buried in the sediments to interpret what is happening in the atmosphere, there’s a missing link in between, and that is the ocean,” says Huang. Further, “how that chromium cycles might change our interpretations of geological records.”

“The evolution of oxygen on Earth is only known in a coarse fashion, but it is crucial to the development and survival of complex multicellular life,” says Ed Boyle, professor of ocean geochemistry of MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS); MIT-WHOI Joint Program director; and study co-author, along with Simone Moos PhD ’18 of the Elementar Corporation. “In addition, there is ongoing concern about the past few decades of decreasing oceanic oxygen levels in the ocean, and we need tools to better understand the ocean’s oxygen dynamics.” 

Bridging a gap

Billions of years ago, when Earth and its atmosphere were essentially devoid of molecular oxygen (O2), chemical reactions and biological metabolisms would have occurred in a chemically reduced, anaerobic environment. During the Great Oxidation Event, which occurred over the course of millions of years, oxygen levels rose planet-wide, and life transitioned accordingly. Further, the environment largely became an oxidized one that grappled with stress processes like rusting and free radicals.

Some evidence has shown that chemical reactions involving chromium track this process, through effects on its isotopes, chromium-52 and chromium-53, and their oxidation states, primarily the trivalent, reduced form Cr (III) and a hexavalent, oxidized one Cr (VI). The latter is more likely to be found in oxygenated, surface seawater and is considered a health and environmental hazard. Previous studies have shown that the upper ocean tends to have more of the heavier isotope than the lighter one, suggesting some preferential uptake by marine microorganisms. The problem, Huang notes, is that after chromium enters the oceans from rivers, scientists don’t really know the mechanisms behind these observations and if the trends are consistent. In today’s oxygen-deficient waters, she says, “chromium could potentially be reduced, and we want to know the isotope signal of that and other chromium processes that might leave an isotope fingerprint.”

To investigate these phenomena, Huang joined two research cruises to the eastern tropical North Pacific Ocean’s oxygen-deficient zone (ODZ) and gathered vertical profiles of seawater samples down to 3,500 meters from across a transect of sea. Some of these seawater samples were frozen to be analyzed for concentrations of trivalent and hexavalent chromium. After being shipped back to the lab, these samples were thawed and purified. The team analyzed the isotope composition of the Cr (III) samples. They then acidified the Cr (VI) samples to convert them to Cr (III) before performing the same isotope analysis as before. The researchers also measured the total chromium in the samples to be able to account for any chemical transformations or migration within the ODZ. With the addition of data from another cruise, Boyle, Moos, and Huang examined the fraction of each isotope over the depth range, compared to an average partitioning, to see if there was any enrichment in a particular area of the ODZ and which oxidation state it existed in. They charted this against the samples’ oxygen levels and put the results in context of known ocean features to help explain how chromium is cycling.

A ground truth for chromium cycling

The oceanographers found a pattern. In surface, oxygenated ocean, hexavalent chromium was consumed, likely by microbial life, and transported deeper, into the ODZ. Around the 200-meter mark, the metal began to accumulate in the seawater, and the lighter isotope, chromium-52, was preferentially reduced. This depth happens to coincide with anaerobic, denitrifying microbes that produce nitrite. Huang says that this could be a sign that nitrogen and chromium cycling are entangled, but that doesn’t rule out other biotic or abiotic mechanisms, like reduction by iron, that could be affecting ocean sediment records.

Chromium doesn’t linger here forever, though. While data showed that most of it remained in oxygen-deficient zone, which extends from 90 to 800 meters, for about 20-50 years, a small portion of it attached to sinking particles, sank into the deep ocean where there is more dissolved oxygen, and later oxidized back to hexavalent chromium. Here, it could begin incorporating and interacting with sediments.

“I think it is exciting that we could determine the chromium [oxidation] species, and from that, we could calculate its isotope fractionation,” says Huang. “Nobody has done that in this way before.”

Their work, Huang says, helps validate chromium as an indicator of different redox environments. “We’re seeing this signal and it’s not vanishing.” Further, it seems consistent over the seasons. However, the team isn’t convinced yet. They plan to test this in other oxygen-deficient zones around the world to see if a similar chromium signature pops up, as well as investigate the composition of the sinking particles carrying the trivalent chromium and the surface of ocean sediments, in order to get a more complete picture of the ocean’s involvement.

For now, they advise against drawing conclusions, but are guardedly optimistic about its potential. “I think people need to interpret this proxy with more caution,” says Huang. “It might not be purely the atmospheric oxygen that is determining the measurement, but there could be other [biotic or abiotic] processes in the ocean that could alter their paleorecords.” So, they suggest not to read into the chromium signals in the paleorecord too much, yet.

This research was supported, in part, by the National Science Foundation. More

The ocean’s “biological pump” describes the many marine processes that work to take up carbon dioxide from the atmosphere and transport it deep into the ocean, where it can remain sequestered for centuries. This ocean pump is a powerful regulator of atmospheric carbon dioxide and an essential ingredient in any global climate forecast.

But a new MIT study points to a significant uncertainty in the way the biological pump is represented in climate models today. Researchers found that the “gold standard” equation used to calculate the pump’s strength has a larger margin of error than previously thought, and that predictions of how much atmospheric carbon the ocean will pump down to various depths could be off by 10 to 15 parts per million.

Given that the world is currently emitting carbon dioxide into the atmosphere at an annual rate of about 2.5 parts per million, the team estimates that the new uncertainty translates to about a five-year error in climate target projections.

“This larger error bar might be critical if we want to stay within 1.5 degrees of warming targeted by the Paris Agreement,” says Jonathan Lauderdale, a research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “If current models predict we have until 2040 to cut carbon emissions, we’re expanding the uncertainty around that, to say maybe we now have until 2035, which could be quite a big deal.”

Lauderdale and former MIT graduate student B.B. Cael, now at the National Oceanography Center in Southampton, U.K., have published their study today in the journal Geophysical Research Letters.

Snow curve

The marine processes that contribute to the ocean’s biological pump begin with phytoplankton, microscopic organisms that soak up carbon dioxide from the atmosphere as they grow. When they die, phytoplankton collectively sink through the water column as “marine snow,” carrying that carbon with them.

“These particles rain down like white flaky snow that is all this dead stuff falling out of the surface ocean,” Lauderdale says.

At various depths the particles are consumed by microbes, which convert the particles’ organic carbon and respire it into the deep ocean in an inorganic, mineral form, in a process known as remineralization.

In the 1980s, researchers collected marine snow at locations and depths throughout the tropical Pacific. From these observations they generated a simple power law  mathematical relationship — the Martin curve, named after team member John Martin — to describe the strength of the biological pump, and how much carbon the ocean can remineralize and sequester at various depths.

“The Martin curve is ubiquitous, and it’s really the gold standard [used in many climate models today],” Lauderdale says.

But in 2018, Cael and co-author Kelsey Bisson showed that the power law derived to explain the Martin curve was not the only equation that could fit the observations. The power law is a simple mathematical relationship that assumes that particles fall faster with depth. But Cael found that several other mathematical relationships, each based on different mechanisms for how marine snow sinks and is remineralized, could also explain the data.

For instance, one alternative assumes that particles fall at the same rate no matter the depth, while another assumes that particles with heavy, less-consumable phytoplankton shells fall faster than those without.

“He found that you can’t tell which curve is the right one, which is a bit troubling, because each curve has different mechanisms behind it,” Lauderdale says. “In other words, researchers might be using the ‘wrong’ function to predict the strength of the biological pump. These discrepancies could snowball and impact climate projections.”

A curve, reconsidered

In the new study, Lauderdale and Cael looked at how much difference it would make to estimates of carbon stored deep in the ocean if they changed the mathematical description of the biological pump.

They started with the same six alternative equations, or remineralization curves, that Cael had previously studied. The team looked at how climate models’ predictions of atmospheric carbon dioxide would change if they were based on any of the six alternatives, versus the Martin curve’s power law.

To make the comparison as statistically similar as possible, they first fit each alternative equation to the Martin curve. The Martin curve describes the how much marine snow reaches various depths through the ocean. The researchers entered the data points from the curve into each alternative equation. They then ran each equation through the MITgcm, a general circulation model that simulates, among other processes, the flux of carbon dioxide between the atmosphere and the ocean.

The team ran the climate model forward in time to see how each alternative equation for the biological pump changed the model’s estimates of carbon dioxide in the atmosphere, compared with the Martin curve’s power law. They found that the amount of carbon that the ocean is able to draw down and sequester from the atmosphere varies widely, depending on which mathematical description for the biological pump they used.

“The surprising part was that even small changes in the amount of remineralization or marine snow making it to different depths due to the different curves can lead to significant changes in atmospheric carbon dioxide,” Lauderdale says.

The results suggest that the ocean’s pumping strength, and the processes that govern how fast marine snow falls, are still an open question.  

“We definitely need to make many more measurements of marine snow to break down the mechanisms behind what’s going on,” Lauderdale adds. “Because probably all these processes are relevant, but we really want to know which are driving carbon sequestration.”

This research was supported, in part, by the National Science Foundation, the Simons Collaboration on Computational Biogeochemical Modeling of Marine Ecosystems, and the UK National Environmental Research Council. More

Gregory Norris is an expert on quantifying firms’ impacts on the environment over the life cycles of their products and processes. His analyses help decision-makers opt for more sustainable, Earth-friendly outputs.

He and others in this field of life-cycle assessment (LCA) have largely gone about their work by determining firms’ negative impacts on the environment, or footprints, a term most people are familiar with. But Norris felt something was missing. What about the positive impacts firms can have by, for example, changing behaviors or creating greener manufacturing processes that become available to competitors? Could they be added to the overall LCA tally?

Introducing handprints, the term Norris coined for those positive impacts and the focus of MIT’s Sustainability and Health Initiative for NetPositive Enterprise (SHINE). SHINE is co-led by Norris and Randolph Kirchain, who both have appointments through MIT’s Materials Research Laboratory (MRL).

Positive impacts

“If you ask LCA practitioners what they track to determine a product’s sustainability, 99 out of 100 will talk about footprints, these negative impacts,” Norris says. “We’re about expanding that to include handprints, or positive impacts.”

Says Kirchain, “we’re trying to make the [LCA] metrics more encompassing so firms are motivated to make positive changes as well.” And that could ultimately “increase the scope of activities that firms engage in for environmental benefits.”

In a February 2021 paper in the International Journal of Life Cycle Assessment, Norris, Kirchain, and colleagues lay out the methodology for not only estimating handprints but also combining them with footprints. Additional authors of the paper are Jasmina Burek, Elizabeth A. Moore, and Jeremy Gregory, who are also affiliated with the MRL.

“By giving handprints a defendable methodology, we get closer to the ideal place where everything that counts can be counted,” says Jeff Zeman, principal of TrueNorth Collective, a consulting firm for sustainability. Zeman was not involved in the work.

As a result, Zeman continues, “designers can see the positive impact of their work show up in an organization’s messaging, as progress toward its sustainability goals, and bridge their work with other good actors to create shared benefits. Handprints have been a powerful influence on me and my team — and continue to be.”

How it works

Handprints are measured with the same metrics used for quantifying different footprints. For example, a classic metric for determining a product’s water footprint is the liters of water used to create that product. The same product’s water handprint would be calculated by determining the liters of water saved through a positive change such as instituting a new manufacturing process involving recycled materials. Both footprints and handprints are measured using existing life-cycle inventory databases, software, and calculation methods.

The SHINE team has demonstrated the impact of adding handprints to LCA analyses through case studies with several companies. One such study described in the paper involved Interface, a manufacturer of flooring materials. The SHINE team calculated the company’s handprints associated with the use of “recycled” gas to help heat its manufacturing facility. Specifically, Interface captured and burned methane gas from a landfill. That gas would otherwise have been released to the atmosphere, contributing to climate change.

After calculating both the company’s handprints and footprints, the SHINE team found that Interface had a net positive impact. As the team wrote in their paper, “with the SHINE handprint framework, we can help actors to create handprints greater than, and commensurate with, their footprints.”

Concludes Norris: “With this paper, we hope that work on sustainability will get stronger by making these tools available to more people.”

This work was supported by the SHINE consortium. More

The cost of the rechargeable lithium-ion batteries used for phones, laptops, and cars has fallen dramatically over the last three decades, and has been a major driver of the rapid growth of those technologies. But attempting to quantify that cost decline has produced ambiguous and conflicting results that have hampered attempts to project the technology’s future or devise useful policies and research priorities.

Now, MIT researchers have carried out an exhaustive analysis of the studies that have looked at the decline in the prices these batteries, which are the dominant rechargeable technology in today’s world. The new study looks back over three decades, including analyzing the original underlying datasets and documents whenever possible, to arrive at a clear picture of the technology’s trajectory.

The researchers found that the cost of these batteries has dropped by 97 percent since they were first commercially introduced in 1991. This rate of improvement is much faster than many analysts had claimed and is comparable to that of solar photovoltaic panels, which some had considered to be an exceptional case. The new findings are reported today in the journal Energy and Environmental Science, in a paper by MIT postdoc Micah Ziegler and Associate Professor Jessika Trancik.

While it’s clear that there have been dramatic cost declines in some clean-energy technologies such as solar and wind, Trancik says, when they started to look into the decline in prices for lithium-ion batteries, “we saw that there was substantial disagreement as to how quickly the costs of these technologies had come down.” Similar disagreements showed up in tracing other important aspects of battery development, such as the ever-improving energy density (energy stored within a given volume) and specific energy (energy stored within a given mass).

“These trends are so consequential for getting us to where we are right now, and also for thinking about what could happen in the future,” says Trancik, who is an associate professor in MIT’s Institute for Data, Systems and Society. While it was common knowledge that the decline in battery costs was an enabler of the recent growth in sales of electric vehicles, for example, it was unclear just how great that decline had been. Through this detailed analysis, she says, “we were able to confirm that yes, lithium-ion battery technologies have improved in terms of their costs, at rates that are comparable to solar energy technology, and specifically photovoltaic modules, which are often held up as kind of the gold standard in clean energy innovation.”

It may seem odd that there was such great uncertainty and disagreement about how much lithium-ion battery costs had declined, and what factors accounted for it, but in fact much of the information is in the form of closely held corporate data that is difficult for researchers to access. Most lithium-ion batteries are not sold directly to consumers — you can’t run down to your typical corner drugstore to pick up a replacement battery for your iPhone, your PC, or your electric car. Instead, manufacturers buy lithium-ion batteries and build them into electronics and cars. Large companies like Apple or Tesla buy batteries by the millions, or manufacture them themselves, for prices that are negotiated or internally accounted for but never publicly disclosed.

In addition to helping to boost the ongoing electrification of transportation, further declines in lithium-ion battery costs could potentially also increase the batteries’ usage in stationary applications as a way of compensating for the intermittent supply of clean energy sources such as solar and wind. Both applications could play a significant role in helping to curb the world’s emissions of climate-altering greenhouse gases. “I can’t overstate the importance of these trends in clean energy innovation for getting us to where we are right now, where it starts to look like we could see rapid electrification of vehicles and we are seeing the rapid growth of renewable energy technologies,” Trancik says. “Of course, there’s so much more to do to address climate change, but this has really been a game changer.”

The new findings are not just a matter of retracing the history of battery development, but of helping to guide the future, Ziegler points out. Combing all of the published literature on the subject of the cost reductions in lithium-ion cells, he found “very different measures of the historical improvement. And across a variety of different papers, researchers were using these trends to make suggestions about how to further reduce costs of lithium-ion technologies or when they might meet cost targets.” But because the underlying data varied so much, “the recommendations that the researchers were making could be quite different.” Some studies suggested that lithium-ion batteries would not fall in cost quickly enough for certain applications, while others were much more optimistic. Such differences in data can ultimately have a real impact on the setting of research priorities and government incentives.

The researchers dug into the original sources of the published data, in some cases finding that certain primary data had been used in multiple studies that were later cited as separate sources, or that the original data sources had been lost along the way. And while most studies have focused only on the cost, Ziegler says it became clear that such a one-dimensional analysis might underestimate how quickly lithium-ion technologies improved; in addition to cost, weight and volume are also key factors for both vehicles and portable electronics. So, the team added a second track to the study, analyzing the improvements in these parameters as well.

“Lithium-ion batteries were not adopted because they were the least expensive technology at the time,” Ziegler says. “There were less expensive battery technologies available. Lithium-ion technology was adopted because it allows you to put portable electronics into your hand, because it allows you to make power tools that last longer and have more power, and it allows us to build cars” that can provide adequate driving range. “It felt like just looking at dollars per kilowatt-hour was only telling part of the story,” he says.

That broader analysis helps to define what may be possible in the future, he adds: “We’re saying that lithium-ion technologies might improve more quickly for certain applications than would be projected by just looking at one measure of performance. By looking at multiple measures, you get essentially a clearer picture of the improvement rate, and this suggests that they could maybe improve more rapidly for applications where the restrictions on mass and volume are relaxed.”

Trancik adds the new study can play an important role in energy-related policymaking. “Published data trends on the few clean technologies that have seen major cost reductions over time, wind, solar, and now lithium-ion batteries, tend to be referenced over and over again, and not only in academic papers but in policy documents and industry reports,” she says. “Many important climate policy conclusions are based on these few trends. For this reason, it is important to get them right. There’s a real need to treat the data with care, and to raise our game overall in dealing with technology data and tracking these trends.”

“Battery costs determine price parity of electric vehicles with internal combustion engine vehicles,” says Venkat Viswanathan, an associate professor of mechanical engineering at Carnegie Mellon University, who was not associated with this work. “Thus, projecting battery cost declines is probably one of the most critical challenges in ensuring an accurate understanding of adoption of electric vehicles.”

Viswanathan adds that “the finding that cost declines may occur faster than previously thought will enable broader adoption, increasing volumes, and leading to further cost declines. … The datasets curated, analyzed and released with this paper will have a lasting impact on the community.”

The work was supported by the Alfred P. Sloan Foundation. More