The material accounts for more than 7% of global carbon emissions, according to some estimates
3 min
Bill Gates , Jeff Bezos and former Los Angeles Laker Rick Fox are part of a new wave of investors and entrepreneurs looking to make one of the world’s worst pollutants greener.
Concrete accounts for more than 7% of global carbon emissions, according to some estimates. That is roughly the same as the CO undefined produced by all of India and more than double the amount produced by the global aviation industry.
Most of those emissions are caused by cement, the glue that binds together sand and gravel to make the concrete used to build roads, bridges and tall buildings.
Concrete, the second-most-used material in the world after water, is popular because it is cheap, relatively easy to produce, fire-resistant and extremely strong.
“It’s the most democratic material,” said Admir Masic , an associate professor of civil and environmental engineering at the Massachusetts Institute of Technology.
It is also very, very dirty. Cement is made by heating limestone and clay at around 2,700 degrees Fahrenheit in giant kilns and turning them into marble-sized granules called clinker, which are then turned into a powder and mixed with other materials. As it heats up, the limestone releases a lot of CO undefined , and the whole process is often powered by fossil fuels such as coal or gas.
Big cement producers and startups including Brimstone and Partanna, a startup based in the Bahamas and headed by three-time NBA champion Fox, are developing new technologies to produce cement while producing less CO undefined . Breakthrough Energy Ventures, which was founded by Gates and is backed by Bezos, Jack Ma and Michael Bloomberg among others, Fifth Wall and other venture firms have poured tens of millions of dollars into these companies.
These companies are being motivated in part by the federal government, which is dishing out grants and setting aside billions to decarbonise materials such as cement. Local regulators are also encouraging these new technologies. California in 2021 passed a law to cut emissions from cement and New York in 2023 issued rules that limit emissions on concrete used in state-funded construction projects.
Some companies are trying to make cement from different materials that are less polluting. Brimstone said it developed a way to make cement from rocks that contain no carbon. The company said it has raised around $60 million in venture funding to date.
Others are selling substitutes for cement so that concrete mixers need less of it. Eco Material Technologies, for example, harvests coal ash from landfills and volcanic ash from mines and sells it to concrete mixers. These substitutes aren’t new, but the company says it has worked out ways to increase its share in concrete.
“Our goal is to be able to use the last several generations of trash as the next several generations of greener concrete,” said CEO Grant Quasha .
Still others are removing pollutants from the air. The Halifax, Nova Scotia-based startup CarbonCure came up with a process to pump CO undefined into concrete as it is being made and raised $80 million in venture funding this past year.
Partanna, which uses brine from saltwater desalination to make concrete, said homes made from its material suck carbon out of the air.
It is unclear if the greener concrete alternatives will ever catch on broadly. Building codes have rigid rules on what concrete must contain, and many builders don’t like to try out new materials, Masic said.
Cost is another issue. Eco Material’s most environmentally friendly cement alternative, for example, costs around twice as much as standard cement, according to Quasha. CEO Cody Finke said Brimstone’s cement will be as cheap or cheaper than the common sort, but the company has yet to build a factory.
“If I go to the developing world and tell them you’re going to have to pay 20% more for your cement, they won’t do it,” said Eric Toone , a managing partner at Breakthrough Energy Ventures.
Even if some of these new technologies succeed, the startups have yet to prove that they can produce green cement at the vast quantities needed to make a dent in global warming.
Still, Toone said cement makers have no choice but to find cheap ways to cut emissions because ditching the material isn’t an option.
“Cement is sort of this wonder material,” he said. “It’s so cheap, it’s so valuable, it’s so good for what we need that it’s really hard to think of ways around it.”
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What a quarter-million dollars gets you in the western capital.
Alexandre de Betak and his wife are focusing on their most personal project yet.
Unmarried home buyers say they are giving priority to a financial foundation over a legal one
4 min
The big wedding can wait. Couples are deciding they would rather take the plunge into homeownership.
In reshuffling the traditional order of adult milestones, some couples may decide not to marry at all, while others say they are willing to delay a wedding. Buying a home is as much, if not more of a commitment, they reason. It helps them build financial stability when the housing market is historically unaffordable.
In 2023, about 555,000 unmarried couples said that they had bought their home in the previous year, according to a Wall Street Journal analysis of Census Bureau data. That is up 46% from 10 years earlier, when just under 381,000 couples did the same.
Unmarried couples amounted to more than 11% of all U.S. home sales. The percentage has climbed steadily over the past two decades—a period in which marriage rates have fallen. These couples make up triple the share of the housing market that they did in the mid-1980s, according to the National Association of Realtors.
To make it work, couples must look past the significant risk that the relationship could blow up, or something could happen to one partner. Without a marriage certificate, living situations and finances are more likely to fall into limbo, attorneys say.
Mark White, 59 years old, and Sheila Davidson, 62, bought a lakeside townhouse together in Newport News, Va., in 2021. But only her name is on the deed. He sometimes worries about what would happen to the house if something happened to her. They have told their children that he should inherit the property, but don’t have formal documentation.
“We need to get him on the deed at some point,” Davidson said.
White and Davidson both had previous marriages, and decided they don’t want to do it again. They also believe tying the knot would affect their retirement benefits and tax brackets.
Couples that forgo or postpone marriage say they are giving priority to a financial foundation over a legal one. The median homeowner had nearly $400,000 in wealth in 2022, compared with roughly $10,000 for renters, according to the Federal Reserve’s Survey of Consumer Finances.
Even couples that get married first are often focused on the house. Many engaged couples ask for down-payment help in lieu of traditional wedding gifts.
“A mortgage feels like a more concrete step toward their future together than a wedding,” said Emily Luk, co-founder of Plenty, a financial website for couples.
Elise Dixon and Nick Blue, both 29, watched last year as the Fed lifted rates, ostensibly pushing up the monthly costs on a mortgage. The couple, together for four years, decided to use $80,000 of their combined savings, including an unexpected inheritance she received from her grandfather, to buy a split-level condo in Washington, D.C.
“Buying a house is actually a bigger commitment than an engagement,” Dixon said.
They did that, too, getting engaged eight months after their April 2023 closing date. They are planning a small ceremony on the Maryland waterfront next year with around 75 guests, which they expect to cost less than they spent on the home’s down payment and closing costs.
The ages at which people buy homes and enter marriages have both been trending upward. The median age of first marriage for men is 30.2, and for women, 28.6, according to the Census Bureau. That is up from 29.3 and 27.0 a decade earlier. The National Association of Realtors reported this year that the median age of first-time buyers was 38, up from 31 in 2014.
Family lawyers—and parents—sometimes suggest protections in case the unmarried couple breaks up. A prenup-like cohabitation agreement spells out who keeps the house, and how to divide the financial obligations. Without the divorce process, a split can be even messier, legal advisers say.
Family law attorneys say more unmarried people are calling for legal advice, but often balk at planning for a potential split, along with the cost of drawing up such agreements, which can range from $1,000 to $3,000, according to attorney-matching service Legal Match.
Dixon, the Washington condo buyer, said she brushed off her mother’s suggestion that she draft an agreement with Blue detailing how much she invested, figuring that their mutual trust and equal contributions made it unnecessary. (They are planning to get a prenup when they wed, she said.)
There are a lot of questions couples don’t often think about, such as whether one owner has the option to buy the other out, and how quickly they need to identify a real-estate agent if they decide to sell, said Ryan Malet, a real-estate lawyer in the D.C. region.
The legal risks often don’t deter young home buyers.
Peyton Kolb, 26, and her fiancé figured that a 150-person wedding would cost $200,000 or more. Instead, they bought a three-bedroom near Tampa with a down payment of less than $50,000.
“We could spend it all on one day, or we could invest in something that would build equity and give us space to grow,” said Kolb, who works in new-home sales.
Owning a place where guests could sleep in an extra bedroom, instead of on the couch in their old rental, “really solidified us starting our lives together,” Kolb said. Their wedding is set for next May.
Homes and weddings have both gotten more expensive, but there are signs that home prices are rising faster. From 2019 to 2023, the median sales price for existing single-family homes rose by 44%, according to the National Association of Realtors. The average cost of a wedding increased 25% over that time, according to annual survey data from The Knot.
Roughly three quarters of couples move in together before marriage, and may already be considering the trade-offs between buying and renting. The cost of both has risen sharply over the past few years, but rent rises regularly while buying with a fixed-rate mortgage caps at least some of the costs.
An $800 rent hike prompted Sonali Prabhu and Ryan Willis, both 27, to look at buying. They were already paying $3,200 in monthly rent on their two-bedroom Austin, Texas, apartment, and felt they had outgrown it while working from home.
In October, they closed on a $425,000 three-bed, three-bath house. Their mortgage payment is $200 more than their rent would have been, but they have more space. They split the down payment and she paid about $50,000 for some renovations.
Her dad’s one request was that the house face east for good fortune, she said. Both parents are eagerly awaiting an engagement.
“We’re very solid right now,” said Prabhu, who plans to get married in 2026. “The marriage will come when it comes.”
