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.
The Australian 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.
Researchers across the globe are also looking into renewable plant-based solutions as well. Scientists are exploring alginate—a biopolymer obtained from brown seaweed—to create unfired clay bricks as an alternative to conventional fired bricks and concrete blocks. Swiss researchers are also moving cement-bonded wood products into the realm of weight-bearing wood-based concrete.
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, 1.2 billion people live in areas of severely constrained agricultural areas, and an additional 2 billion live in areas where agricultural water scarcity is high to very high. 4 billion people experience severe water scarcity at least one month of the year, and over 2 billion people live in countries experiencing high water stress. One third of the world’s largest groundwater systems are in distress and by 2030, water scarcity in arid and semi-arid regions will displace anywhere from 24 million to 700 million people.
In addition, 35 percent of all water in distribution systems is lost to phenomena like pipe leakage, meter errors and unauthorized consumption. WIth 80 percent of energy being used for pumping, some of that energy is being lost to leaky systems. 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), two billion people—one out of every four people on earth—do not have access to sanitation facilities, and 673 million people are currently defecating out in the open.
Lack of access to sanitation and open defecation can lead to issues in health, well-being, economics, and society. Poor sanitation is linked to disease transmission, some of which can exacerbate stunted growth. Poor sanitation can result in anxiety, risk of sexual assault, and lost educational opportunites, reducing human well being and social and economic development. WHO estimates that 432,000 people die from diarrhea each year in regions with inadequate sanitation.
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, phosphorus, 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 can be installed 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.
In our oceans, overfishing has far-reaching consequences for oceanic and human ecosystems. With methods that take too many fish and sea creatures out of the oceans, the natural nutrient cycle that fosters the perpetuation of life becomes disrupted. Populations decrease, there are less fish to catch, less life in the sea, and this ends up impacting economies and the health of our earth.
If even just 50 percent of the 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 meat 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 meat production and overfishing, with a meat 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 or stripping the sea of life, researchers are getting closer and closer to growing meat and seafood in a lab that rivals cuts of meat from living animals.
Known as “cell-based meat,” researchers take cells from a living animal through an anesthetized biopsy from an antibiotic-free animal; 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.
In addition, instead of waiting for years for the animal to come to a maturity where it can be slaughtered, cell-based meat can be produced in a number of weeks. The way slaughter-free meat is cultivated varies depending upon which of the 40 emerging cell-based meat and six cell-based seafood companies are developing the technology. The holy grail of cell-based meat and seafood is a product indistinguishable from that taken from a live animal.
Some companies are attempting to get to this end 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 meat, ready for sale or for processing into other cell-based meat products.
In addition to taste parity, price parity is also on the minds of cell-based meat makers. Cell-based meat megalith Memphis Meats, with it’s massive $161 million in funding, believes that price parity is on the horizon.
What isn’t in parity between cell-based and animal-derived meat is the cruelty, antibiotics, environmental degradation, and water costs. All cell-based meat and seafood companies are sure that, at scale, lab-grown meat will be less destructive to the ecosystem than the continued cultivation of animals.
A hybrid plant and cell-based ground meat option from Future Meat Technologies could be in markets as early as this year (2021). Other companies are working to create structurally sound and tasty steaks, pork, tuna, salmon, duck, and mre.
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 reason why US greenhouse gas emissions rose in 2018 after a three-year decline.
While overall carbon emissions dropped during the Covid-19 pandemic, the decline may not persist if we return pre-pandemic habits and behaviors. 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 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. Thirty six electric electric ducted fans (EDF) sit in four flaps that begin in a vertical position for take off and tilt to a fully horizontal position when the plane is ready to cruise. Shaped like a manta ray, the lift to drag ratio of the Lilium Jet is 21:1—the highest lift to drag ratio amongst all sustainable aviation.
As a result of a lower drag coefficient, the use of lightweight carbon fiber, and the distributed propulsion coming from the 36 separate EDFs, 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.
However, and this is a big however, the true impact of the Lilium jet depends upon battery production. Extracting lithium for lithium ion batteries is cheap in money, but expensive in water, ecosystemic destruction, and pollution. The cobalt and nickel for batteries are concentrated in one place on earth, and creating unethical, unsafe extraction economies.
Even if Lilium utilizes the abundance of aluminum by using aluminium ion batteries, there are still negative impacts on our earth from extraction, refining, and processing. To truly be a force for good, Lilium will have to measure and balance more than just carbon emissions.
By reading a select number of engineering blogs, university students can gain access to the thoughts of some of the best engineers in the world, and get on the path to becoming one themselves.
The concepts of civil engineering are particularly well-suited for the game environment, emphasizing the proper distribution of resources, the management of supply chains, and how the built environment interacts with the lived environment.
Engineers might be the only group of people where you can give them a problem—and they can consider it a gift. The engineering mind thrives on hunting for elegant solutions to complex tasks. That doesn’t mean you should give an engineering student a homework assignment for the holidays, but it does mean you can have some fun with the gift you eventually select.
Not long ago, self-driving cars were science fiction. Today, not so much. Influential companies like Tesla, Uber, Apple, and Google boast dynamic auto-drive programs, and many new startups are following their lead.
Over 45 percent of all Americans live with unhealthy air. According to the 2020 State of the Air report, the situation has been getting worse, year after year. An increasing number of Americans are living in communities impacted by unhealthy levels of pollution, more particle pollution days, and higher annual particle levels. As a changing climate threatens our ability to protect human health, significant action is needed from policymakers, professionals, corporations, and the general public.