QA &

Q: WHAT GOT YOU INTERESTED IN RECYCLING BATTERIES?

A: As a research associate at Princeton University working in 2018 on renewable energy, electrification was seen as a big opportunity, especially lithium-ion (li-ion) batteries. People first think about making better batteries, but with the environmental and safety issues associated with mining the materials, along with their limited recycling and likely disposal into landfills, I saw recycling li-ion batteries as an underexplored sector. In the U.S., only about 5% of used li-ion batteries are currently recycled. Today, there are about two million electric vehicles on the road, a figure expected to jump to roughly 26 million by 2030! The demand for energy storage for grid stabilization, as well as solar and wind energy is growing rapidly as well. Some experts estimate that over 80 metric tons of li-ion batteries will need to be recycled in the U.S. in 2030 alone. This is just the beginning!

Q: WHY IS IT SO DIFFICULT TO RECYCLE THEM?

A: Unlike more commonly and easily recycled lead-acid batteries, li-ion batteries are extremely complex. The cost of recycling often outstrips the value of recovered battery components. Most current methods use acids to leach out metals — cobalt, nickel and lithium. This process is typically slow and energy-intensive, produces wastewater

New Lives for Discarded Batteries

Chao Yan ’17 Ph.D. Research Associate, Princeton University’s Keller Center for Innovation in Engineering Education contaminated with toxic metal ions, and loses critical battery materials. The cost of then refining the recovered metals is very high and often involves using toxic organic solvents. Additional transportation, material inventory and energy costs complicate traditional recycling processes. Combining these costs with elevated demand and prices of pure materials, we have a critical shortage of materials. This makes recycling — smartly — a true imperative.

Q: HOW DOES PRINCETON NuENERGY TACKLE THIS PROBLEM?

A: Rather than reducing batteries to their source compounds, we use a simpler method to separate valuable materials and advanced plasma technologies to clean them — minimizing impurities for direct return to battery manufacturing. We can produce battery-grade materials that are just like virgin materials.

Q: WHAT ARE SOME NOTEWORTHY MILESTONES IN THE HISTORY OF THE COMPANY?

A: In 2021, we were awarded the U.S. National Grand Prize by CleanTech Open, the world’s largest clean technology accelerator program. We then received grant funding from the U.S. Department of Energy and formed a partnership with the Fortune Global 500 electronics manufacturer, Wistron Corp., to bring our technology to market. In

Founder, Princeton NuEnergy

October 2022, our 500-ton pilot line with Wistron was launched.

Q: WHAT ARE YOUR NEAR-TERM GOALS?

A: Over the next five years, we plan to build more than five additional discrete recycling facilities containing 10+ production lines with capacity to process over 50,000 tons of spent batteries and manufacturing scrap. Each facility will reduce CO2 emissions by up to 80%, water use by 70% and the overall cost by 50% compared to current industrial recycling processes.

Q: HOW CAN WE IMPROVE THE SUSTAINABILITY OF THE LI-ION INDUSTRY?

A: For example, when switching from the internal combustion engine to electric cars, the idea was to reduce emissions and energy use. Recycling was an afterthought. Going forward, we need to think more carefully about technology decisions and best practices we take in recycling li-ion batteries to optimize cost and minimize environmental concerns. We believe that direct recycling and Princeton NuEnergy can make a substantial positive impact to this new electrified world.

Sustainability Modelers Are Reshaping Architectural Design

Erin Heidelberger ’20, M.S. Georgia Tech ’22

Environmental Performance Analyst, Kohn Pederson Fox

Q: WHAT DOES YOUR JOB ENTAIL?

A: As a member of the environmental performance team, I work with designers to improve the performance and sustainability of projects, from individual buildings to urban planning initiatives. By running simulations, I give them options to consider, such as how to orient a building to access more daylight and reduce energy use, or if there’s too much sunlight, how to shade it. More comprehensively, I advise them on ways to minimize the carbon footprint of a building’s operations.

Q: WHAT ELEMENTS OF A BUILDING OR DEVELOPMENT DO YOU EVALUATE?

A: I take a holistic approach to design improvement, such as analyzing the way a building’s shape, orientation and envelope impact energy use; how the thermal properties of windows and window-to-wall ratios affect cooling need; and how to maximize sunlight for longer periods of the year. examine water consumption, including the potential to reuse wastewater on site, stormwater management solutions and flooding risk mitigation. Clients are also starting to look at the embodied carbon content of materials and how to use them more efficiently.

Q: HOW DO YOU ANALYZE A BUILDING’S PERFORMANCE?

A: One of the primary tools I use is a program called Grasshopper within Rhinoceros, the 3D modeling tool. It allows me to manipulate building geometries, which in turn lets me examine the relationship between shape and sun angle, the ratio of grass to pavement with respect to flooding, and to test options for lowering a building’s embodied carbon by varying parameters, such as the type of cladding, room heights and windows, among other simulations. We need to make these calculations in a reasonable amount of time. If an architect asks you how to handle X, Y and Z and you take three weeks to get back, the design may be completely new at that point.

Q: WHEN DO PERFORMANCE MODELS FAIL?

A: We make assumptions in our simulations that can miss entire populations. One example is occupancy schedule inputs to energy models — when people are home — which is typically based on the premise of 9-5 office jobs. This fails to capture a range of living and working situations: people working multiple jobs, part-time, at night and on the weekend. Another is the condition of peoples’ houses. The models are predicated on buildings being up to code in insulation and air tightness, but in lower-income neighborhoods, with lots of deferred maintenance, this is not the case.

Q: HOW DO WE EVALUATE AND IMPROVE THE PERFORMANCE OF EXISTING BUILDINGS?

A: Designers need to focus more on this. Within adaptive reuse, we can upgrade buildings’ envelopes and systems, or we can expand existing buildings, rather than knock them down, and even reuse materials.

Q: HOW HAVE ARCHITECTS’ ROLES CHANGED IN THE SUSTAINABILITY SPACE?

A: There’s a greater sense of urgency around sustainability and architects are starting to take ownership of this. For a long time, we focused on design, leaving the technical aspects of performance to engineers. Because we’re involved in the early stages of design, we can have a big impact — the farther along, the less you can do. As an adjunct at NJIT, I stressed to my students, for example, that if they’re dealing with a building’s embodied carbon, they need to think about it before they’ve selected materials, not after.