Cement is a widely used material that is currently responsible for 5 to 6 percent of annual carbon emissions—the third-ranking cause of emissions behind fossil fuels and deforestation.
The reason for the high rate of carbon emissions from cement lies in the decarbonization of limestone. To ensure the limestone can serve as a binder in cement (i.e., the paste that makes everything in concrete stick together), it is roasted to liquefaction in a kiln to catalyze a chemical reaction where calcium carbonate splits into calcium oxide (the material needed for concrete) and carbon dioxide (a waste product). Sixty percent of carbon emissions from concrete result from this process, with the other 40 percent resulting from energy use in production.
To compound this very real environmental issue, sand— a commonly used aggregate in concrete—has been over-extracted and is becoming increasingly scarce. The over extraction of sand can lead to ecosystem degradation, loss of species, social conflicts, and black markets. Preventing damage from the concrete industry and the over-taxation of our sand resources is a prime example of an issue built for environmental engineering to overcome.
Strategies that aim to simultaneously decrease carbon emissions, reduce sand use, and provide viable waste-management strategies in concrete production are popping up all over the world in the form of eco-concrete and eco-bricks.
Researchers in Australia have figured out a way to create cement from the hundreds of thousands of tons of glass that a failing recycling system was no longer processing. To create waste glass-based concrete, researchers break the glass waste down into increasingly smaller sizes, until it becomes a fine powder. The powder is then combined into the cement mix with other, more traditional industrial waste-products (e.g., fly ash, blast-furnace slag, etc.) and tested for stability.
Researchers are currently making cement with a 10 to 30 percent waste-glass composition, resulting in cheaper, stronger, and lighter cement with functional insulation, fire-resistance, and a lower emissions threshold. Researchers are confident that over time, the high-quality prefabricated slabs of concrete made from glass-waste can contain more glass and eventually be scaled up to industrial production.
Another breakthrough in environmental engineering that tackles the concrete problem is one completely outside the concrete box. An invention based out of New Zealand, ByFusion has created a system to turn all forms of plastic waste into concrete brick-shaped building blocks.
The mobile brick-maker, called the Byfusion blocker, shreds any form of plastic waste (no sorting or pre-washing needed); fuses the shredded plastic into blocks using superheated water and compression (no adhesives needed); and creates modular plastic bricks that can be used for non-load bearing construction.
In addition to being nontoxic and having a lower carbon footprint than concrete blocks, the bricks don’t crumble under pressure, provide high-level sound and temperature insulation, and can be made into customized shapes and densities. While not useful for all forms of construction, this solution could eliminate the need for concrete in a wide range of infrastructural uses, while fighting against the scourge of plastic that currently threatens our planet.
All life on earth relies on water, and humans are no exception to this rule. Water scarcity for humans, whether due to physical shortages or lack of access, is already a big issue—one that will continue to expand through population growth, rapid urbanization, and the devastating effects of climate change.
According to the United Nations, 700 million people already suffer from water scarcity. By 2030, water scarcity in arid and semi-arid regions will displace anywhere from 24 million to 700 million people, and 4.8 to 5.7 billion people could live in water-scarce areas by 2050.
In addition, 8.6 trillion gallons of water are lost each year through leaks in water distribution systems—losses that also translate into billions of hours of wasted energy pumping water into leaks instead of pumping water into the intended destinations. With the fact that only about 1 percent of the world’s freshwater is available to us, getting water to all people effectively and without waste is a huge problem for environmental engineering to solve.
To tackle the enormous issue of water scarcity, researchers took to the sky—or, more accurately, the atmosphere.
While the atmosphere only contains an estimated 0.04 percent of the world’s freshwater, that percentage translates into 12 quadrillion gallons of water. According to the chief officer of XPRIZE—a design competition to create technological advances for a better, safer, and more sustainable world—that 120,000,000,000,000,000,000 gallons is 300 million times the amount 7 billion people require for household needs!
Before the contest, many air-to-water devices existed, but none on an affordable or scaleable level. Or at least, that was the case until David Hertz, Laura Doss-Hertz, and Richard Groden founded the Skysource/Skywater Alliance; entered the XPRIZE water abundance competition; and developed a technology that could pull 2000 liters (~530 gallons) of water per day from the atmosphere for less than two cents per liter using renewable technology inside of a shipping container.
The prize-winning innovation combines two formerly separate technologies: dehumidification and biogasification. The dehumidification process combines warm and cold air, condenses atmospheric humidity, and replicates a rainstorm inside the shipping container. To ensure functionality in low-humidity environments, the Skywater can stimulate condensation at the level of dew-point (i.e. less humidity than what is required for a rainstorm). A byproduct of the “rain” is a naturally occurring gas called ozone (O3). The Skywater technology pumps ozone through the water at the point of collection, and as the ozone binds to the water, bacteria and other impurities are eliminated.
Powering the container relies on biomass gasification. In biogasification, wood, coconut shells, or other biological feedstock is cooked in a low-oxygen environment, resulting in a syngas that can power the technology required for dehumidification. The inventors of the device also note that the technology could be powered by wind or solar in regions where biomass is scarce.
In addition to creating a system that could be used anywhere and without massive, inefficient infrastructure, the utilization of shipping containers is also a waste management strategy. Generally, more shipping containers are imported than exported, resulting in a surplus of shipping containers that can now be used for a higher purpose.
According to the World Health Organization (WHO), 2.4 billion people—one out of every three people on earth—do not have access to sanitation facilities, and 946 million people are currently defecating out in the open.
Lack of access to sanitation and open defecation can lead to a host of health issues spread through water and insects, malnutrition, 1.4 million preventable diarrhea-related deaths in children annually, environmental contamination, and olfactory pollution.
In addition, the World Bank estimates that poor sanitation costs our global community $260 billion dollars each year. Compounding the issue is the fact that many urban centers are becoming more populous at a rate that infrastructure cannot match, or are becoming populous with a socioeconomic demographic that does not have enough money to ever build the necessary sanitation systems.
Environmental engineering mindsets are required to figure out how to protect people from the negative impacts of open defecation and sanitation systems that can’t keep up with demand.
Bill Gates recently announced that the first innovation to toilet technology in over 200 years will solve the issue of bringing sanitation to the people without the need for full-scale sanitation systems.
The “tiger toilet” is a self-contained vermicomposting toilet that requires no sewer system and very little water to function. It is a simple pour-flush toilet on top of a worm-filled compartment. The name of the toilet comes from the tiger worm (Eisenia fetida), whose natural habitats are animal dung heaps and who are the star player in the tiger toilet revolution.
The toilets are simple yet extremely effective. After doing their duty, a person’s fecal matter drops down into a vermifilter (a container) where the tiger worms then eat and process the waste. After feasting on a meal they find quite tasty, the worms remove 99 percent of the pathogens and leave behind less-than-15 percent of waste by weight—a biomatter rich in nitrogen, phosphorous, carbon, and potassium that can be removed from the system and used for fertilizer.
There is a fair amount of water created as a byproduct of the process, which although not clean enough to drink, is clean enough to go into the ground and complete the filtration process without contaminating soil or groundwater. In addition to not requiring any central sewage infrastructure, the design of the toilets lead to fewer smells, attract fewer flies, and do not provide a habitat for mosquitos. Gates hopes that the toilets can cost as little as $350, creating an affordable and scalable option for sanitation that be used anywhere.
According to Project Drawdown—a research-based comprehensive solution to global warming—the meat-centric Western diet is responsible for one-fifth of global emissions. It found that “if cattle were their own nation, they would be the world’s third-largest emitter of greenhouse gases.” Of the top four commodities driving deforestation, beef is responsible for more than twice as much deforestation as soybeans, palm oil, and wood products (the other top three drivers) combined.
In addition, the production of beef results in more than 200 times the global warming emissions of soy, and more than 60 times that of palm oil per calorie. If that weren’t enough, there are beef farms who use soy as feedstock, thereby compounding deforestation and greenhouse emissions.
If even just 50 percent of world’s population adopted vegan and vegetarian diets, emissions from meat production and deforestation could be reduced by as much as 70 percent and 63 percent, respectively. However, due to cultural and personal concerns, many are skeptical that this strategy will be widely effective. Taming the seemingly insatiable cravings for beef while also protecting life from the devastating impacts of deforestation will require creative environmental engineering.
Companies and start-ups all over the world are tackling the negative environmental impact of beef through a beef-production relocation strategy of truly sci-fi proportions. Instead of raising a methane-emitting animal in grazing land that was formerly a carbon-sinking forest, researchers are getting closer and closer to growing cuts of beef in a lab that rival cuts of beef from a cow.
Known as “cell-based beef,” researchers take cells from a living animal through an anesthetized biopsy from an antibiotic-free cow; digest the sample with enzymes; and break the tissue into individual cells. From there, the individual cells that comprise meat (i.e., cells for nerves, blood vessels, muscle fibers, fat, collagen, tendons, etc), are selected. Once selected, they are placed into a culture medium (a liquid rich with salts, vitamins, proteins, and sugars) and kept moving in a bioreactor (a huge vat) so they can grow. Projections show that from the cells of ten animals, 62,500 times more meat can be produced in this manner than if the ten animals were slaughtered.
From this point, the way slaughter-free meat is cultivated varies depending upon the company creating it. Some companies grow each cell-type individually and combine in the proper proportions to create an unstructured end product that resembles ground beef.
Other companies are attempting to create market-advantage by growing the cultivated cells together using 3D technology—i.e., growing the cuts of meat like they would grow in nature. Companies using 3D strategies either utilize pre-formed scaffolding where seeded cells grow into a predetermined shape, or they use 3D printing technology to build the meat and scaffolding simultaneously. Using biological, mechanical, and electrical cues, the cells will grow into a cohesive piece of raw beef, ready for sale or for processing into other cell-based meat products.
Players in the cell-based meat market tout their products as cruelty-free, antibiotic-free, more environmentally friendly, less water-intensive, and more ethical than conventional meat. However, at the cost of $50 per cell-based steak, the technology will need to catch on before it can be scaled to be as affordable as beef. In addition, while this method of beef production does have promise to be less emissions-heavy than traditional beef, it will still be more emissions heavy than plants for the foreseeable future.
When it comes to total human impact on climate change, the impact of air travel ranges from 4 to 9 percent. Jet fuel released from planes bonds with oxygen to form carbon dioxide, and also releases soot into the atmosphere. Both CO2 and soot can result in positive radiative forcing—a phenomenon by which energy and heat are allowed into the earth but hinder the flow of heat out of the earth, thereby raising global temperatures. The altitude at which planes travel may trigger a series of chemical reactions that have a net warming effect as well.
While fuel efficiency, better aerodynamics, improved route mapping, and biofuels are all strategies being used by the aviation industry, aviation is part of the the reason why US greenhouse gas emissions rose in 2018 after a three-year decline. Environmental engineering is well-suited to figure out how to best protect life on earth from the warming effect catalyzed by air travel.
The electrification of air travel is currently underway, with one solar-powered around-the-world-flight for one already completed in 2016. Although replacing fossil-fuel airliners may not be a reality until 2050, researchers are starting the journey toward an electrified air-fleet with short-range planes built for a small number of passengers.
Perhaps the most exciting breakthrough in the pack is the Lilium Jet—a 100 percent electric plane with a 300 km range—that can travel 300 km/h for one hour, takes off vertically, and can be ordered on-demand like an carshare vehicle.
The key to the vertical take off and the lightning-fast speed is in the tilting-flap technology. Twelve electric engines sit in a flap that begins at a vertical position for take off and tilt to a fully horizontal position when the plane is ready to cruise. As a result of a lower drag coefficient and the use of lightweight carbon fiber, the energy consumption per seat and kilometer in a Lilium Jet is comparable to an electric car, but the jet travels much faster.
The impact of the Lilium Jet on the environment could be huge in terms of reducing the time and fossil fuels spent commuting long distances, reducing the need for cars, and not increasing infrastructure burden as they will not require roads or bridges. If battery technology improves to the point where they are light and powerful enough to scale, the Lilium Jet model could prove an interesting first step toward a completely reimagined eco-responsible air fleet.
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