Originally published on Ensia.

A roomful of materials scientists, gathered at UCLA for a recent conference on “grand challenges in construction materials,” slowly passed a brick-size white block around the room. They held in their hands, briefly, part of the solution to one of those grand challenges. The white block, rock solid and surprisingly lightweight, was a new alternative to cement, the glue that holds together aggregate, or crushed rock, to make the world’s most ubiquitous building material: concrete.

Production of cement — and, by extension, concrete — has a large environmental footprint, mostly due to the huge amount of energy it takes to heat limestone, cement’s key ingredient. The process of creating cement emits upward of 80 percent of the cement’s weight in carbon dioxide and accounts for about 5 percent of human-generated carbon dioxide emissions annually. Though the white block’s production still requires some of the carbon dioxide–emitting fuel use of typical cement making, carbon dioxide is also one of the ingredients used to create it. About one-third carbon dioxide by mass, the cement-like substance reduces its carbon footprint by sequestering carbon dioxide inside the finished product.

Concrete, and the cement that binds it, is the most widely used material in the world, and its usage is on the rise. From 2011 through 2013, China used more than 6.5 billion metric tons (7.2 billion tons) of cement — more than the US used in the entire 20th century. Between 2006 and 2050, global production of cement is expected to increase to between 3.7 billion metric tons (4.1 billion tons) and about 4.4 billion metric tons (4.9 billion tons) a year.

Since concrete isn’t going away, reducing the carbon intensity of its production is becoming a global imperative. New technologies and approaches are being developed to cut down on concrete’s environmental downsides — including utilizing industrial byproducts to reduce cement usage, recycling existing concrete, producing self-healing concretes that reduce the need for new concrete, and creating entirely new materials.

But no perfect solution exists. That yet-unnamed white block is not completely carbon-negative, nor can it replace typical cement completely, explains Fredrik P. Glasser, a professor at the University of Aberdeen in Scotland who is part of the team that developed the cement alternative. In this case, limestone is replaced with waste carbon dioxide and magnesium from a cement production facility and a desalination plant in Qatar, but carbon-emitting high heats are still required.

Glasser says it’s less about replacing cement than reusing the large quantities of carbon dioxide it produces. “The emphasis has to be on taking that CO2 and making useful products from it,” he says. The material he’s helping develop is still a few years away from market, but it’s proving in tests to be a viable replacement for some concrete and insulation in building projects. His goal isn’t to compete with cement but to “eat away at the edges” of what it’s currently being used for, shaving down the global need for cement and the carbon emissions it produces.

Researchers and businesses all over the world are trying to find other ways to carve niches into this market — by developing novel material approaches or simply making concrete less environmentally harmful.

The Canadian company CarbonCure Technologies has developed a process that injects waste carbon dioxide into a typical concrete production process, effectively replacing a small amount of cement with carbon dioxide without compromising the concrete’s strength or integrity. Once in the mix, the carbon dioxide changes into calcium carbonate, the chemical equivalent of the limestone used in the production of conventional cement.

Four concrete producers in North America have started using CarbonCure’s technology, including Argos in Atlanta and Vulcan in Springfield, Virginia, and about a dozen more are negotiating licenses, according to Sean Monkman, the company’s vice president of technology development. One user, over the course of a single week after the technology was installed, saw its carbon dioxide emissions drop from 124.5 metric tons (137 tons) to 119 metric tons (131 tons) by replacing some of the carbon-intensive cement in the concrete mix with waste carbon dioxide, Monkman says.

CarbonCure’s technology is a small retrofit to the concrete production process — just a computer system, a tank of waste carbon dioxide, and a tube that can pump that carbon dioxide into the concrete mix. “It’s simple. It doesn’t require any huge change in the way things are normally operated,” Monkman says. “For a conservative industry like concrete, it’s got to be simple if people are going to want to do it.”

Change is slow, many in the industry concede, which has made it challenging for new material approaches to catch on. And though typical cement has a high carbon footprint, there’s still no cheaper option.

Yet another way to reduce the carbon footprint of concrete is to recycle it. Researchers at the University of Notre Dame are developing a cost-effective method by which producers of precast concrete — concrete formed into a mold and brought to building sites — can effectively recycle their waste concrete into aggregate and reuse it in the production of construction beams.

Engineering professor Yahya Kurama, who’s leading this research, says the environmental toll of mining the aggregate used to make concrete — often from riverbeds and mountaintops — has been largely ignored. “You’re not only destroying the environment but you’re spending the energy to dig that material out, and then you have to transport it,” he says. By reducing the amount of virgin aggregate they mine, concrete companies can cut both environmental impacts and costs.

Another approach to reducing the need for new concrete is the advent of self-healing concrete — concrete mixes augmented with various polymers, bacteria, and healing agents that can automatically respond to cracks. Researchers in the United Kingdom are currently testing out a number of experimental self-healing concretes, including one embedded with tiny capsules that open when the concrete cracks and form new solid calcium carbonate.

None of these approaches on its own will erase the environmental impact of concrete. But the more alternatives there are, the more sustainable the industry can be.

Originally published on Ensia.

Much of the stuff around us at any given moment — be it product, commodity, or raw material — was once on a boat. To get from wherever it was made or processed or harvested to wherever it’s used or consumed, all this stuff embarks on a seaborne journey around the world. It happens thousands of times a day, on tens of thousands of vessels moving from port to port. Ships handle roughly 90 percent of global trade, nearly 10 billion metric tons (11 billion tons) of stuff per year.

Boats and ports are only a part of the picture. Airlines, railroads, trucks, warehouses, refrigerators, delivery people — the international system of goods movement is integral to the way we live in the 21st century. It’s also a huge source of opportunity to reduce humans’ environmental footprint.

Ship shape

MSC Valeria, an ultra-large containership from the Mediterranean Shipping Company S.A., of Geneva, is tugged by a boat.

The 10 billion tons of stuff shipped around the planet in 2014 is two-thirds more than what was moved in 2000. “Retail sales in the United States and across the world are increasing, in spite of all the economic cycles,” says Jean-Paul Rodrigue, a professor at Hofstra University and an expert in transport geography. “There’s more people, there’s more consumption.”

More than 47,000 big ships handle the bulk of this cargo, most of which (by weight) is made up of crude oil, iron ore, coal and other building blocks of the modern world. About 6,100 container ships carry the consumer goods we’re more likely to encounter and purchase — the televisions and socks and frying pans of day-to-day life. Transported around the world in standardized containers, this stuff has dramatically transformed shipping from a dockside hustle of men hauling crates to a highly mechanized, multimodal system that can have a box of South American bananas off a boat and on sale in the US within hours.

The environmental cost of moving those bananas is, of course, complex. Big ships can use more than 100 metric tons (110 tons) of fuel oil per day and can take two weeks or more to traverse oceans. Shipping’s international nature makes it tricky to control; measures such as fuel regulations and emissions standards have long implementation periods and are slow to achieve greenhouse gas reductions and environmental goals. Standards vary inside and outside so-called “emissions control areas” established by the International Maritime Organization, a United Nations agency focused on shipping.

The fuel used in ships, for instance, still contains low levels of sulfur and is highly polluting, and it’s been estimated that shipping accounts for 3 to 4 percent of human-caused carbon emissions. A recent report from the European parliament estimated that number could rise as high as 17 percent by 2050. In spite of this potential, shipping hasn’t been prioritized in any of the international agreements coordinated through the UN Framework Convention on Climate Change, and the latest agreement coming out of the COP 21 talks in Paris does not include stipulations on shipping or the high emissions caused by air freight.

Even so, there’s a reason all this stuff travels by boat. Aside from being the cheapest mode, it’s also the most carbon-efficient method of shipping: A big ship will emit about 10 grams (0.4 ounces) of carbon dioxide to transport 1 metric ton of cargo 1 kilometer (2 tons of cargo 1 mile). That’s roughly half as much as a train, one-fifth as much as a truck and nearly a fiftieth of what an airplane would emit to accomplish the same task.

“If ships were to move to cleaner diesel fuels, that would be a big reduction in emissions,” says Genevieve Giuliano, director of the METRANS Transportation Center at the University of Southern California. All the major shipping lines are looking into new fuels and other sustainability measures. Earlier this year, Harvey Gulf International Marine became the first North American company to add liquefied natural gas, which produces less CO2 than conventional marine fuels, as a fuel for an offshore support vessel. And the first two cargo ships are set to begin using LNG for hauling cargo. Others are expected to follow, but transitioning ship engines on a wide scale will take time.

Still, progress is underway. From technological improvements such as retrofitted rudders and propellers to enhanced weather routing, shipping companies are eyeing many ways to improve their efficiency. “Freight is becoming more efficient by the day,” Giuliano says. “And in the short term, efficiency gains are going to be the biggest contribution to greenhouse gas reductions.”

For instance, newer ships have been designed to carry more without a proportional increase in fuel use. The biggest ship today is capable of transporting close to 20,000 of the type of containers typically carried by a semi-trailer on the highway, a huge jump from the roughly 2,500 that the first purpose-built containerized ships could carry in the 1970s. And as this capacity has grown, ports have adapted to handle the influx.

“Ports are getting more and more automated and even robotized,” says Rodrigue. Ships can essentially plug into the ports where they dock, tapping into local power instead of idling their huge engines and burning hundreds of tons of fuel to sit still. Automated cranes can quickly unload and reload ships to reduce their time in port. And the same systems can quickly move those thousands of containers onto the trucks and trains that carry them off across the land.

Trucks and trains

Trucks drive near City Hall to protest shipping container fees being assessed against independent truckers as part of the ports’ Clean Truck Program to allow only newer, less-polluting trucks at the ports, on November 13, 2009, in Los Angeles, California.

The era of huge container ships has led to the development of logistics hubs, with rail yards, truck bays, and massive warehouses that receive, sort, and redistribute all these goods. Transporting freight on rail is more energy-efficient than transporting it by truck, says Asaf Ashar, an emeritus research professor with the University of New Orleans’s National Ports & Waterways Initiative. But while it makes sense energy-wise to transport freight on rail for most mid- and long-range hauls in the US, for example, the flexibility of trucking and the wide geographic spread of the country means that most stuff is eventually moved to its point of sale or use by truck. According to the American Trucking Associations, trucks carry about 70 percent of the tonnage of stuff moving throughout the US annually, requiring 3 million trucks and more than 37 billion gallons (140 billion liters) of diesel fuel.

The companies doing all this trucking understand the scale of these operations, and their heavy environmental costs. “It’s their bottom line. They want to find more fuel-efficient vehicles, and they do a lot of research into optimization algorithms for the routing of their trucks, from making sure they turn in one direction to minimizing wear and tear,” Rodrigue says. “When you have a fleet of thousands of vehicles and you’re able to save 1 or 2 percent of fuel or maintenance costs because of more efficient routing, it’s big money at the end of the year.”

And those solutions may not be far off. “I think that the first autonomous driving will take place in freight,” says Ashar. Automated driving can go slower for longer hours than a human driver, with big implications for fuel efficiency, he says, so these companies — and potentially the environment — have a lot to save by reducing or even eliminating the human element. “Within a few years, there’s no need for a guy to sit in a big truck on the highway.”

Automation is seen by many as the biggest change coming to the system of goods movement, and it is already being implemented in a wide variety of ways. From the automated cranes moving containers from ships to trains and trucks to algorithms that schedule and route deliveries, automation is already having an impact on the overall efficiency of the goods-movement system, cutting both costs and energy demands. Port automation has also been found to dramatically improve the use of land within port complexes, thereby prolonging or even eliminating the need to engage in environmentally costly expansion projects. And many expect the energy savings and efficiency gains of automated systems to play a much bigger role in reducing the overall environmental impact of the global goods movement system.

“Not anything within a year or two, but within a decade or so we could see very interesting stuff,” says Rodrigue. “A lot of vehicles will be self-driving, dropping stuff automatically at some specific, preset points, and the loading and unloading will be somehow automated, and people will just need to pick up their stuff.” The reduced energy costs of automated vehicles and optimized routing and deliveries could mean we’ll need fewer energy-sucking vehicles on the road to get all the stuff we need.

Special delivery

FedEx Express electric vehicle.

The question of how people ultimately get all this stuff is another dominant conversation in the goods-movement world. With the rapid growth of e-commerce and delivery options from retailers such as Amazon that promise packages within day or hours, moving all these individual packages from seller to buyer has created new challenges, particularly in terms of carbon emissions from delivery vehicles. Ideas for addressing the congestion and energy requirements of the so-called “last-mile” issue range from centralized delivery boxes to cargo bicycles. Big companies like FedEx are investing in hybrid or all-electric delivery vehicles. Amazon is famously investigating the potential of delivery by battery-powered drones, which could reduce the company’s reliance on traditional vehicles and their emissions. But many experts say the idea is just speculation at this point.

With the rise of 3D printing, some technologists are looking at the potential of distributed manufacturing — factories interspersed throughout urban areas where machines can print whatever part or product a consumer could want or need, eliminating the need to ship a part across an ocean or put it in a box in the back of a delivery truck.

Such fabrication labs may serve a niche audience, says Ashar, but they’re unlikely to be able to compete economically with the large-scale manufacturing system already in place. However, he doesn’t expect the current system to prevail in the long run, either. As the economic efficiency of shipping increases on sea and land, it will no longer make sense to concentrate huge factories in places like China. He sees more factories in more locations, with the parts and raw materials moving between them at less cost and with more energy efficiency than today. “I don’t see less transportation,” Ashar says. “I see more transportation but less energy consumption for that transportation.”

Efficiency gains and developments in automation may have the biggest influence on how the environmental footprint of our global system of goods movement evolves in the coming years. And even if self-driving trucks and delivery drones eventually revolutionize the movement of stuff over land, almost all of that stuff will still start its long journey on a boat.