The Sustainable City
The United Nations predicts that 70% of the world’s population will live in urban centers in the next 30 years. The city of the future will need to function differently than it does today, and the change over the next three decades will be rapid.
by Marisa Demers
Illustrated by Valerie Chiang
Caltech alumni thinkers, inventors, and engineers are helping with that transformation. They are questioning norms about how a city should operate—Do we have to import our water?—and are devising new solutions—Why not make asphalt good for the environment? By reinventing every element of a city, they are helping to lower the planet’s carbon footprint and possibly stave off the worst effects of climate change.
A Remedy for Range Anxiety
Talal Balaa, MS (MS ’89) traveled in his electric vehicle to a place few other plug-in drivers in 2011 would dare to go: Mt. Wilson.
To reach the summit, Balaa drove his first-generation Nissan Leaf through switchback curves and high elevations. He arrived at his destination with nearly zero driving range and no charging station in sight.
“As an EV driver, I should not have to avoid places because they are out of range,” says Balaa, who returned to his home in South Pasadena thanks to gravity, regenerative braking, and some luck. “There has to be a better option.”
Most Americans agree. Range anxiety and the limited stock of charging stations are the top reasons U.S. drivers are reluctant to switch to EVs, according to a Volvo study. Addressing these concerns could help reduce greenhouse gas emissions, too. According to the EPA, a typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year.
Balaa set out to devise a solution. He spent the next few years designing a portable, solar-powered EV charger that the average EV owner could use. His invention looks like a traditional car cover but is embedded with small solar Stirling engines that look like spinning bicycle wheels. The energy generated is funneled to a storage device and an inverter converts the power into the type of electricity that EVs need. Even better for Balaa, it meets his need for practicality: it weighs less than 20 pounds, is easy to assemble, and fits into a 9×18 parking space.
Balaa’s prototype is at the threshold of current technology, he says. With support from an angel investor, Balaa plans to manufacture his product after he has figured out how to extract as much power as possible from the solar engines in as little time as possible. It is a challenging problem that, if resolved, could change the future of transportation.
“No one believed the 4-minute mile could be broken until somebody did it. Then others started breaking the record, too,” Balaa says. “Once someone eliminates some of solar power’s downsides, other people will join in and find even better solutions.”
Deep Water
Thomas Fleming, MS (MS ’84) wants to make every drop of water count. As a senior sustainability analyst for Santa Monica, he is part of an ambitious effort to make the city water self-sufficient by the end of 2023.
Like most Southern California communities, this small but densely populated city imports a significant portion of its water from the Colorado River and Northern California watersheds. Yet, as droughts become more severe and long-lasting due to climate change—the western United States is currently in a 22-year megadrought—the water supply is dwindling. Other water districts, notably Costa Mesa’s, have taken note and made strides toward water independence.
Soon, Santa Monica will rely on its groundwater aquifer for more than 90% of its drinking water. The city spent millions on upgrading and building new facilities to improve stormwater harvesting and wastewater capture. A portion of that water will be purified and injected back into the aquifer while the remaining amount will be treated and used for non-potable uses such as irrigation and toilet flushing. Water conservation is another critical part of achieving water self-sufficiency because it is a low-cost effort that brings high returns, Fleming says. Since the city implemented a conservation plan in 2015, individual daily water consumption in Santa Monica has dropped 20%.
Tomorrow’s urban centers will need to have a relentless focus on water conservation and innovation but there is a good reason to believe people are up for the challenge, Fleming says. Despite population growth, Americans use as much water as they did in 1970, according to the U.S. Geological Survey.
“Water is the fluid of life,” Fleming says. “It is why we search for it on other planets and marvel about its discovery on the moon. Here on Earth, humans have an innate connection to nature, and there is even a phrase for it— biophilia. We are wired to be good stewards of the environment.”
Paving the Way
There are about 4 million miles of public roads in the United States and if Shelly Zhang’s, PhD (PhD ’16) plan takes off, they will soon be pulling double duty as carbon storage for used plastic.
Her company, Molten, remedies two unfortunate realities of the recycling and road industries. First, U.S. Environmental Protection Agency (EPA) data shows that only 30% of plastic bottles are recycled; the rest are sent to landfills, shipped to other countries, or incinerated. Second, the carbon dioxide-emitting formula used to create asphalt has remained relatively unchanged for the past 100 years.
Molten takes plastic bottles, used tires, and used motor oil and turns them into eco-friendly crack sealants and rejuvenator oils, an essential ingredient that makes asphalt pliable and easy to lay onto roads. Molten’s first product, the crack sealant, costs less than her competitors’ products and contains 98 plastic bottles per box.
Zhang already had years of experience in this sector when she launched Molten. Her father ran an online store that sold asphalt pour pots and other tools to road crews, and she would often help him make cold calls to potential clients. When he died just a few months before her Caltech graduation, Zhang decided to keep his business going. After a few years of attending trade shows, she noticed a trend. “I realized that nothing really changes,” Zhang says. “Businesses make too much money to really think about innovating.”
At the same time, Zhang was trying to find her entry into sustainability. When a business investor suggested she address the plastic crisis, Zhang found an uncommon connection. Both plastic and rejuvenator oil are derived from petrochemicals. In 2019, she began researching new methods to break down the polymers in plastic bottles so they could be added into asphalt. Zhang’s long-term goal, she says, is to repurpose 100% of waste plastic worldwide.
Today, Molten has sold 6 million pounds of its crack sealant, its rejuvenator oil is patent pending, and it is preparing to release a second green product. With her success, Zhang hopes others will join her in creating a greener world. “The only thing stopping us from creating more sustainable cities is us,” Zhang says. “We have an energy problem, a waste problem, a plastic problem, and we need as many people as possible working on solutions.”
From Less Bad to Net Zero
Americans spend 90% of their days indoors, according to the EPA, and this lifestyle exacts a toll on our planet from the natural resources used to construct homes and buildings to the energy we consume in them.
Jerry Yudelson, MS & MBA (BS ’66), known as the “Godfather of Green,” has been championing sustainable building practices for nearly 30 years. While working as a marketer for a Portland engineering design company in the mid-1990s, Yudelson discovered he had a knack for translating engineering and science concepts in ways that were accessible to general audiences. Yudelson used this skill to become a green building writer, speaker, and consultant. His 12 books and 100 conference presentations balance big ideas and bold sustainability goals with practical advice and data on cost savings. His publications are the kind that architects, builders, and property owners dog-ear, scribble on, and place on their bookshelves for years.
They also help influence change. An early supporter of the Leadership in Energy and Environmental Design (LEED) rating system—who has trained more than 4,000 people on how to obtain certification— Yudelson published Reinventing Green Buildings: Why Certification Systems Aren’t Working and What We Can Do About It. This book, published in 2016, called for higher LEED standards, a head-turning move at the time. Just two years after the book’s release, LEED issued a new net zero designation. The benchmark of the construction industry, net zero signifies that the amount of energy and water consumed is equal to the amount produced.
Building on Yudelson’s legacy, sustainability advocates continue to push for even higher standards. For instance, today, it is much more common to examine a structure’s total carbon footprint, not just its energy-related emissions. The mining of limestone for a cement foundation, the manufacturing of steel to frame a house, and the transportation of building materials to the work site all release carbon dioxide into the atmosphere. “A lot of stuff we did not even think about when I first started in green building is being talked about now,” Yudelson says. “There is a huge amount of research going on … which is important because the next 10 years will be a critical decade for the planet.”
Marisa Demers is a freelance writer who got her start covering wildfires and breaking news for newspapers. She also worked for Caltech and was most recently an assistant director for the Caltech Associates. A San Gabriel Valley native, she has enjoyed following Caltech’s scientific breakthroughs and student pranks over the years. You can read more of her writing on widestletter.com and follow her on Twitter at @WidestLetter.