Fog Harps? Self-Irrigating Soils? Underwater Kite Makes Electricity from Ocean Tides? Insect Farming Goes High-Tech?!

WHAT THE HECK ARE FOG HARPS?

Around the world, people living where groundwater is scarce but where fog forms have long used a device called a fog harvester to collect potable water.

Fog harvesters are mesh nets, usually one meter squared, set up to have the wind blow through them. As the wind blows fog through the device, the mesh catches the droplets, and gravity pulls the water down into containers underneath. Most of the time, fog harvesters collect about three liters a day per square meter of mesh.

The problem with fog harvesters is their mesh design has to be just the right size to capture and drain the droplets. Too big, and the water vapor passes right through. Too small, and the droplets gather but, due to surface tension, can’t slide down into the collection bucket.

Researcher Jonathan Boreyko and Virginia Tech industrial designer Brook Kennedy partnered up to create a more efficient harvester that they call a “fog harp.” Kennedy, who’d spent time in Northern California, noticed that redwood pine needles are linear, and yet they managed to capture about 30% of each tree’s water needs. Inspired by the trees, Kennedy and Boreyko’s “fog harp” only has vertical wires.

The fix — taking away the horizontal wires — seems deceptively simple. Yet tests showed the fog harp didn’t clog because droplets simply slid down the wires. Instead of collecting three liters of water for every square meter of material, they increased it to nine liters. 

For the pair, water is a humanitarian issue. According to the World Health Organization, half of the world will be living in areas where water isn’t easily available by 2025, while other reports show that global water shortages pose a threat to the national security. 

DEEPER DIVE: WHO, The Guardian, Brook Kennedy

SUPER ABSORBENT GELS FOR SUSTAINABLE AGRICULTURE

The world’s stock of drinkable water is finite. As climate change accelerates, more communities and nations will begin to suffer substantial losses as the conventional global infrastructure seems incapable of picking up the slack — unless we can engineer a new way of procuring water for vulnerable communities.

10% of the world’s freshwater is held in the atmosphere. As climate change continues to unfold, and as the atmosphere becomes even more humid, that percentage will rise. That presents a unique opportunity to develop technology to extract water from the air and use it to irrigate plants…

Scientists already possess technology capable of catching fog, even for collecting the dew that forms overnight on plants and lawns. The problem with these technologies is none of them is  universally applicable, and they are limited to areas where fog forms, or places where wide swings in temperature between day and night cause air to condense. 

DARPA, America’s Defense Advanced Research Projects Agency funded the Atmospheric Water Extraction umbrella program back in November 2020 to the tune of $45 million to help solve the problem. One promising product is an atmospheric water irrigation system based on SMAGS, super moisture absorbent gels, being developed out of the University of TX Austin.

SMAG-soil can harvest water from the air and provide water to the plants upon solar heating regardless of the local accessibility to liquid water resources. As a benefit of this solar-powered atmospheric water irrigation system, agriculture can become geographically and hydrologically independent.

Researchers also hope to use the water-absorbing materials for several other situations, including air-conditioning and self-irrigating soil. 

DEEPER DIVE: American Chemical Society, Interesting Engineering

UNDERWATER KITE DRAWS ENERGY FROM TIDES AND CURRENTS 

Swedish company Minesto has recently signed an agreement to install their underwater kite technology to provide power to the Faroe Islands – a self-governing Danish territory located in the North Atlantic Ocean between Iceland and Norway.

The tech, called Deep Green, takes the concept of stunt kite flying and transfers it into the water to generate electricity. Deep Green follows the same guiding principle as a kite, gliding smoothly through the water as a kite does through the air. It will produce up to 100 KWh.

“Minesto’s Deep Green technology is a unique marine energy converter, a subsea kite that targets the global low-flow tidal stream and ocean current resource,” he says. “It consists of a wing that is tethered to the seabed and that carries a turbine underneath.”

When the kite ‘flies’ through the underwater current, it pushes the turbine through the water at a speed several times the actual stream flow. Electricity is produced in the on-board generator, and transmitted through the tether to cables on the seabed.

Last year, ARPA-E (the Advanced Research Projects Agency–Energy), launched a $38 million program called SHARKS (Submarine Hydrokinetic And Riverine Kilo-megawatt Systems, oof) with the goal of fostering the design of “economically attractive Hydrokinetic Turbines (HKT) for tidal and riverine currents.” Despite the word “turbine” right there, ARPA-E is funding any new technology that can squeeze power out of flowing water, including a novel underwater manta-inspired kite generator under development by SRI.

DEEPER DIVE: SRI, ARPA-E, Deep Green, Underwater Kite

BLACK SOLDIER FLY FARMING

Do you know what the most widely used form of insect farming on the planet is? The most widely used form of insect farming on the planet is the Black Soldier Fly larvae. This fly is an ideal source of food for a wide variety of animals. 

It’s ideally suited for food production due to its rapid production cycle and high concentration of protein. Black soldier fly larvae are a highly efficient, low-impact source of nutrients compared to resource-intensive alternatives like beef, pork, chicken, fishmeal, soymeal, coconut oil and palm kernel oil.

Why does farming black soldier fly larvae matter to us? Food insecurity will worsen in certain parts of the world due to climate change, and so it will become increasingly necessary to find food, for our food. The idea is to start taking pressure off existing protein commodities—soy, fishmeal, and meat—in producing feed and pet food. These commodities carry big environmental footprints particularly as natural resources are stretched thin in a changing climate.

Here’s how you know insect farming is for real: NextProtein, a French-Tunisian startup, recently raised $11.2 million in Series A funding on the premise of designing and building a central facility in Tunisia. NextProtein joins more mature insect startups like Enterra, AgriProtein, and Entocycle.

DEEPER DIVE: Insect Engineers, AgFund News, communitychickens.com, Anthropocene Magazine