Don’t Give up on Desalination

desert and stars

How we manage local water sources drastically alters how we grow crops and get drinking water. Cape Town is currently experience a water crisis that was in the making for decades because of poor water use policies. Desalination plants can help coastal cities provide water to their populace by separating salt from seawater. Wired has a good article on how one company is improving desalination techniques for growing crops, which, they predict can help bring plant life to arid regions.

The structure’s double-layered fibreglass roof transmitted sunlight but captured heat, diverting it through ducts into a compartment at the building’s rear. There, the heat was used to distill freshwater out of seawater for irrigation. The rest was vaporised and sucked through the growing space by fans to cool and humidify the plants, reducing transpiration. Paton calculated that a square metre of crops adjacent to the greenhouse would have required eight litres of water per day to offset what they lost in transpiration. “But inside we were using closer to one litre per square metre per day, and we were growing a better crop.”

Paton is also interested in the long term restorative benefits of his invention. Davies’ model predicted that the greenhouse’s cooling and humidifying effect would seep into the surrounding environment: “You can see there would be a plume of cool air coming off the greenhouse,” he says. And since the region hasn’t always been barren, Paton thinks greenhouses could return parts of it to the naturally vegetated state it was in before overgrazing and drought took hold. “I believe that when you get to, say, 20 years, you’d have enough vegetation to do the job of the greenhouses because they’re creating shade and shared humidity – changing the climate.” Because vegetation sequesters carbon, that also has broader ramifications for mitigating the effects of climate change.

Read more.

Hydroponics in Schools

In urban centres where the land has been used for buildings and other infrastructure there is little room for production farms, so how do we teach children about farming? Well, we can use hydroponics to grow plants and help people understand why plants and food are so great.

A school in New York City has installed a hydroponic greenhouse that makes use of rainwater to grow plants for their school.

There’s no soil in a hydroponic greenhouse, which captures and recirculates rainwater to the roots of plants. In capable hands — though maybe not in 5-year-old hands — the 1,400-square-foot structure can produce up to 8,000 pounds of vegetables every year. It is an experiment in environmental education its founders hope will be replicated in schools citywide.

Two mothers at the school, Sidsel Robards and Manuela Zamora, founded the greenhouse, inspired in 2008 by a trip to the Science Barge, a floating urban farm docked in Yonkers. They got New York Sun Works, the nonprofit green-design group that built the barge, interested enough to execute the greenhouse, a bright, open and wheelchair-accessible space, covered by glass and entered from the school’s third floor, that is essentially the Barge on a roof.

It includes a rainwater catchment system, a weather station, a sustainable air conditioner made of cardboard, a worm-composting center and solar panels. In the center of the room is a system resembling a plant-filled hot tub: an aquaponics system home to a community of tilapia, whose waste is converted into nitrate. The system loses water only when it evaporates to help cool plants, consuming only a tiny fraction of the water that a field of conventional dirt does.

“You basically can have this closed system, this symbiotic thing going on, where plants are eating food, creating waste, you’re converting it and then the plants are taking it up,” said Zak Adams, director of ecological design at BrightFarm Systems, which designed the greenhouse and the barge.

Read the full article at The New York Times.

Thermal Towers in Namibia: Energy and Food

Namibia is examining the feasibility of using solar thermal towers.

Thermal towers work by creating an airflow that spins turbines and the bigger they are the more efficient they become. Namibia appears to be a great place for thermal towers due to the amount of sun it gets. The proposed thermal towers in Namibia will also act as greenhouses for growing food.

A new breed of solar tower may soon be sprouting up in Namibia, providing the nation with a carbon-free source of electricity and food during the day and night. At one and a half kilometers tall and 280 meters wide, these massive solar updraft towers could potentially produce 400MW of energy each – enough to power Windhoek, the nation’s capital. Proposed by intellectual property company Hahn & Hahn, the towers generate energy by forcing heated air through a shaft lined with wind turbines. Additionally, the base of each tower will function as a 37 square km greenhouse where crops can be grown.

Scroll To Top
%d bloggers like this: