Coming Soon: Plant-Based Roads

Plant-Derived Material Can Make Our Roads Carbon-Negative

With all the attention focused on shifting from fossil fuels to renewables, there has been less emphasis on the hundreds of other products made from petroleum and finding substitutes for them. Some of the more common commodities are plastics, shoes, lubricants, paints, sports equipment, synthetic fibers for clothing, and building materials, including roofing.

One ubiquitous product is bitumen, a fossil-fuel-derived binder that holds asphalt aggregate together. A company in Norway is recycling old, damaged roads by using a plant-based binder instead of bitumen. Currently, it has applied this process only to repairing roads. Because Norway is far north, its roads suffer from repeated freeze-thaw cycles. The non-petroleum bioasphaltic binder it employs is lignin — a wood-based material essential to creating structure for trees and plants. The company utilizes a machine called the Carbon Crusher to grind up the top layer of damaged roads before applying the lignin to rebind the ground-up aggregate into a new, durable top layer. 

Approximately 18 billion tons of asphalt make up U.S. roads. All these roads need to be maintained. Asphalt is energy- and resource-intensive, contributing substantially to climate change. Lignin, one of the most abundant natural polymers, is an ideal substitute for crude oil bitumen. Because trees capture CO2 as they grow, using lignin on roads sequesters carbon. This significantly shrinks the carbon impact, especially for road repair. When the road aggregate is recycled, as in Norway, the use of new material is avoided and their associated carbon emissions from production and transportation, often making the entire process carbon-negative.

The process of rehabilitating roads with lignin is faster, cheaper, and more durable than what has been the case with standard bitumen repairs. The biggest plus, however, is its environmental benefits. In Norway, they are finding that lignin is more flexible than bitumen, allowing the repaired surfaces to adapt better to the harsh weather, preventing cracks and making the repairs last longer.

Sweden and the Netherlands are also repairing roads with lignin. The process is starting to be applied to building new roads, but with fewer environmental advantages. The ultimate aim, however, is to stop building new roads — which incentivizes more driving — and focus on better care of existing highways.

It is critical that substitute products, processes, and technologies be found for the myriad of common petroleum-based products that dominate our modern life. What is now underway for asphalt is an instructive model.

3D-Printed Houses

Speedily Built, Disaster Resilient, Energy and Resource Efficient, and Attractive

Big challenges face our society and our planet, none bigger or more pressing than climate change. A ray of hope is how innovative new technologies are tackling a number of these challenges simultaneously. In the housing sector, the 3D-printing process, without much publicity, is launching a revolution in construction materials and methods that are addressing affordability, energy-efficiency, durability, and beauty while erecting structures in record time and at scale.

The software, robotics, and new mixes of materials are technically complex but once the large printers, equipped with robotic arms that travel on rails, are set up, the process is simple. Nozzles at the ends of the robotic arms extrude environmentally friendly concrete mixes, plastics, hemp, mud, wood fibers, and other materials in a layering sequence to create solid, three-dimensional walls. Large sections of the building are printed and then assembled. Tech firms and architects are teaming up to produce designs that incorporate undulating curves that would be extremely time-consuming and prohibitively expensive to create using traditional building practices.

Jason Ballard, CEO of one of these pioneering tech firms, says, “With 3D printing, you not only have a continuous thermal envelope, high thermal mass, and near zero waste, but you also have speed, a much broader design palette, next-level resiliency, and the possibility of a quantum leap in affordability. This isn’t 10 percent better; it’s 10 times better.”

This type of construction is being employed in the Netherlands, Mexico, Canada, the U.S., and in areas impacted by natural or man-made disasters where quick rebuilding is urgent. These houses are built to withstand hurricanes and earthquakes. Entire communities are being designed and constructed; sometimes the printing is on-site and sometimes close by. Lennar Construction, one of the country’s largest builders, is building a 100-unit 3D-printed home development in Texas. Austin, Texas, has become a hub of robotic construction in this country. For example, it is turning out 400-square-foot homes to house 480 homeless people, or 40 percent of its street dwellers. The cost is $4,000 per unit. Printing time for an entire home varies between 24 hours and a week and a half, the longer period being for larger custom homes.  

Biophilic design, the recent term for increasing occupants’ connectivity to the natural world, is being embraced in most of these ventures. The mechanical nature of the production process may give the impression of uniformity and starkness, but the irregularities and imperfections of the striations have led some to compare the homes to adobe architecture. Similarly, the softer curves often harmonize with nature. Carefully thought-out, intricately designed print paths accommodate and hide high-performance mechanicals. 

The potential of 3D-printed housing embraces beauty, livability, economy, and resource efficiency while cutting construction time to a fraction of that required by traditional building methods. How quickly will it move to mainstream?

Insect Saliva Might Be Our Best Plastic Recycler

Once Again the Natural World Is Providing the Ideal Solution

The rapid decline of bee populations, native and European, is well-known. For beekeepers, one of the threats to our hives is waxworms or wax moths. A hive weakened by pesticides can easily become infested by wax larvae.

A few years ago, Dr. Federica Bertocchini, a microbiologist and amateur beekeeper in Spain, made an accidental discovery when cleaning out her waxworm-overrun hive. The larvae were not only chewing through the plastic bag she had put them in but were also dissolving the bag chemically. She and fellow scientists investigated exactly how the insects accomplished this feat. They found that the enzymes or proteins in the waxworm saliva led to the rapid breakdown of polyethylene plastic. These are the first animal enzymes that we know about to degrade plastic, and they do it in a matter of hours and at room temperature.

Because plastic is made to be durable, it is a ubiquitous waste product in our environment, polluting seafood, water, and even human bloodstreams. Over time, it eventually breaks down into small particles, ultimately becoming micro and nano plastic pieces. These particles are found everywhere, from Antarctica to raindrops to tap water, and are posing a growing problem to human health.

Polyethylene bags and other products make up 30 percent of all plastics. In the environment, they break down over hundreds of years through a process known as oxidation. The only large-scale recycling of plastics happening today involves mechanical processes of glycolysis, pyrolysis, and/or methanolysis, all requiring a great amount of energy. Even with these approaches, only about 10 percent of all plastics on the planet are recycled. 

The waxworm’s saliva enzymes oxidize plastic fast and without fossil energy. The only downside could be the release of carbon dioxide if billions of plastic-metabolizing insects are exuding saliva on plastic. More research is needed, but current research suggests scenarios where plastic waste can be “bio-recycled” and eliminate the release of microplastics into the environment. There are indications that these enzymes might yield useful chemicals as part of the degrading process, or even with additional processing steps become new plastic molecules, negating the need for virgin plastic produced from petroleum. 

As saliva enzymes start breaking down plastics at scale, the processes will need to be contained to ensure that our valuable bee colonies are not further threatened.

The Battery Storage Challenge Is Being Solved

Researchers Are Using Less Costly, More Abundant, and Environmentally Benign Materials in Battery Innovation

Using electricity rather than fossil fuels to power our world offers many pluses, especially since electricity is increasingly being produced from the sun, wind, ocean currents and tides. Microgrids and sophisticated software monitoring power needs and providing instantaneous switching are making communities even less dependent on fossil fuels for peak demand periods. Battery storage is the key component that will enable us to get to 100 percent clean electricity. One of the biggest obstacles in this trajectory is the limited, costly, and environmentally damaging mining of lithium, nickel, and cobalt — all of which are used in the manufacture of batteries.

A lot of research is going into making batteries using other, more abundant materials with fewer of the drawbacks of current batteries, namely, flammability and spiky dendrites. The spikes are caused when batteries are charged too quickly and result in shortening the battery’s life.

One international team is getting results using aluminum as one of the electrodes and sulfur as the other with a common salt as the electrolyte. The 230-degree Fahrenheit temperature required to melt the salt and run the battery can be generated internally by normal charging and discharging cycles — charging from the sun during daylight and discharging after dark when electricity is needed. The scientists estimate that the cost will be 12-16 percent of today’s lithium-ion batteries.

In Finland, a functioning sand battery seems to solve the problem of year-round green energy for heat. It works by heating sand (100 tonnes) in an insulated silo using electric-resistant heat produced from surplus wind and solar energy. The sand heats up to almost 1,000 degrees Fahrenheit and maintains this temperature for months until demand and energy prices are high. When needed, air flows through a heat exchanger in the sand to extract the heat for use in a district (neighborhood) heating system or for industries that use a lot of heat like food and beverage processing. The town of Kankaanpää is using the first commercial installation of a sand battery.

Researchers at the University of Cambridge have developed a battery system with a non-toxic form of blue-green algae (Synechocystis) that takes in solar energy by photosynthesis. They have used it to power a microprocessor of a computer for more than six months. It is biologically based, produces renewable energy, and multiplies naturally, making it easily scalable. The device does not require any inputs other than sunlight.

Another solution gaining traction is to produce hydrogen from excess renewable electricity and store it until electricity demand is high and renewable generation low.

These are a few of the storage innovations that are likely to be part of the ensemble of processes that get us to our mid-century, carbon-neutrality goal.